PART 1066—VEHICLE-TESTING PROCEDURES Authority: 42 U.S.C. 7401-7671q. Source: 79 FR 23823, Apr. 28, 2014, unless otherwise noted. Subpart A—Applicability and General Provisions § 1066.1 Applicability. (a) This part describes the emission measurement procedures that apply to testing we require for the following vehicles: (1) Model year 2014 and later heavy-duty highway vehicles we regulate under 40 CFR part 1037 that are not subject to chassis testing for exhaust emissions under 40 CFR part 86. (2) Model year 2022 and later motor vehicles (light-duty and heavy-duty) that are subject to chassis testing for exhaust emissions under 40 CFR part 86, other than highway motorcycles. See 40 CFR part 86 for provisions describing how to implement this part 1066. (b) The procedures of this part may apply to other types of vehicles, as described in this part and in the standard-setting part. (c) The testing in this part 1066 is designed for measuring exhaust, evaporative, and refueling emissions. Procedures for measuring evaporative and refueling emissions for motor vehicles are in some cases integral with exhaust measurement procedures as described in § 1066.801. Subpart J of this part describes provisions that are unique to evaporative and refueling emission measurements. Other subparts in this part are written with a primary focus on measurement of exhaust emissions. (d) The term “you” means anyone performing testing under this part other than EPA. (1) This part is addressed primarily to manufacturers of vehicles, but it applies equally to anyone who does testing under this part for such manufacturers. (2) This part applies to any manufacturer or supplier of test equipment, instruments, supplies, or any other goods or services related to the procedures, requirements, recommendations, or options in this part. (e) Paragraph (a) of this section identifies the parts of the CFR that define emission standards and other requirements for particular types of vehicles. In this part, we refer to each of these other parts generically as the “standard-setting part.” For example, 40 CFR part 1037 is the standard-setting part for heavy-duty highway vehicles and parts 86 and 600 are the standard-setting parts for light-duty vehicles. For vehicles subject to 40 CFR part 86, subpart S, treat subpart I and subpart J of this part as belonging to 40 CFR part 86. This means that references to the standard-setting part include subpart I and subpart J of this part. (f) Unless we specify otherwise, the terms “procedures” and “test procedures” in this part include all aspects of vehicle testing, including the equipment specifications, calibrations, calculations, and other protocols and procedural specifications needed to measure emissions. (g) For additional information regarding the test procedures in this part, visit our website at www.epa.gov https://www.epa.gov/vehicle-and-fuel-emissions-testing/vehicle-testing-regulations. [79 FR 23823, Apr. 28, 2014, as amended at 86 FR 34581, June 29, 2021] § 1066.2 Submitting information to EPA under this part. (a) You are responsible for statements and information in your applications for certification, requests for approved procedures, selective enforcement audits, laboratory audits, production-line test reports, or any other statements you make to us related to this part 1066. If you provide statements or information to someone for submission to EPA, you are responsible for these statements and information as if you had submitted them to EPA yourself. (b) In the standard-setting part and in 40 CFR 1068.101, we describe your obligation to report truthful and complete information and the consequences of failing to meet this obligation. See also 18 U.S.C. 1001 and 42 U.S.C. 7413(c)(2). This obligation applies whether you submit this information directly to EPA or through someone else. (c) We may void any certificates or approvals associated with a submission of information if we find that you intentionally submitted false, incomplete, or misleading information. For example, if we find that you intentionally submitted incomplete information to mislead EPA when requesting approval to use alternate test procedures, we may void the certificates for all engine families certified based on emission data collected using the alternate procedures. This would also apply if you ignore data from incomplete tests or from repeat tests with higher emission results. (d) We may require an authorized representative of your company to approve and sign the submission, and to certify that all the information submitted is accurate and complete. This includes everyone who submits information, including manufacturers and others. (e) See 40 CFR 1068.10 for provisions related to confidential information. Note however that under 40 CFR 2.301, emission data are generally not eligible for confidential treatment. (f) Nothing in this part should be interpreted to limit our ability under Clean Air Act section 208 (42 U.S.C. 7542) to verify that vehicles conform to the regulations. § 1066.5 Overview of this part 1066 and its relationship to the standard-setting part. (a) This part specifies procedures that can apply generally to testing various categories of vehicles. See the standard-setting part for directions in applying specific provisions in this part for a particular type of vehicle. Before using this part's procedures, read the standard-setting part to answer at least the following questions: (1) What drive schedules must I use for testing? (2) Should I warm up the test vehicle before measuring emissions, or do I need to measure cold-start emissions during a warm-up segment of the duty cycle? (3) Which exhaust constituents do I need to measure? Measure all exhaust constituents that are subject to emission standards, any other exhaust constituents needed for calculating emission rates, and any additional exhaust constituents as specified in the standard-setting part. See 40 CFR 1065.5 regarding requests to omit measurement of N 2 4 2 4 (4) Do any unique specifications apply for test fuels? (5) What maintenance steps may I take before or between tests on an emission-data vehicle? (6) Do any unique requirements apply to stabilizing emission levels on a new vehicle? (7) Do any unique requirements apply to test limits, such as ambient temperatures or pressures? (8) What requirements apply for evaporative and refueling emissions? (9) Are there any emission standards specified at particular operating conditions or ambient conditions? (10) Do any unique requirements apply for durability testing? (b) The testing specifications in the standard-setting part may differ from the specifications in this part. In cases where it is not possible to comply with both the standard-setting part and this part, you must comply with the specifications in the standard-setting part. The standard-setting part may also allow you to deviate from the procedures of this part for other reasons. (c) The following table shows how this part divides testing specifications into subparts: Table 1 of § 1066.5—Description of Part 1066 Subparts This subpart Describes these specifications or procedures Subpart A Applicability and general provisions. Subpart B Equipment for testing. Subpart C Dynamometer specifications. Subpart D Coastdowns for testing. Subpart E How to prepare your vehicle and run an emission test. Subpart F How to test electric vehicles and hybrid electric vehicles. Subpart G Test procedure calculations. Subpart H Cold temperature testing. Subpart I Exhaust emission test procedures for motor vehicles. Subpart J Evaporative and refueling emission test procedures. Subpart K Definitions and reference material. § 1066.10 Other procedures. (a) Your testing. (b) Our testing. (c) Exceptions. [79 FR 23823, Apr. 28, 2014, 80 FR 9120, Feb. 19, 2015] § 1066.15 Overview of test procedures. This section outlines the procedures to test vehicles that are subject to emission standards. (a) The standard-setting part describes the emission standards that apply. Evaporative and refueling emissions are generally in the form of grams total hydrocarbon equivalent per test. We set exhaust emission standards in g/mile (or g/km), for the following constituents: (1) Total oxides of nitrogen, NO X (2) Hydrocarbons, HC, which may be expressed in the following ways: (i) Total hydrocarbons, THC. (ii) Nonmethane hydrocarbons, NMHC, which results from subtracting methane, CH 4 (iii) Total hydrocarbon-equivalent, THCE, which results from adjusting THC mathematically to be equivalent on a carbon-mass basis. (iv) Nonmethane hydrocarbon-equivalent, NMHCE, which results from adjusting NMHC mathematically to be equivalent on a carbon-mass basis. (v) Nonmethane organic gases, NMOG, which are calculated either from fully or partially speciated measurement of hydrocarbons including oxygenates, or by adjusting measured NMHC values based on fuel oxygenate properties. (3) Particulate matter, PM. (4) Carbon monoxide, CO. (5) Carbon dioxide, CO 2 (6) Methane, CH 4 (7) Nitrous oxide, N 2 (8) Formaldehyde, CH 2 (b) Note that some vehicles may not be subject to standards for all the exhaust emission constituents identified in paragraph (a) of this section. Note also that the standard-setting part may include standards for pollutants not listed in paragraph (a) of this section. (c) The provisions of this part apply for chassis dynamometer testing where vehicle speed is controlled to follow a prescribed duty cycle while simulating vehicle driving through the dynamometer's road-load settings. We generally set exhaust emission standards over test intervals and/or drive schedules, as follows: (1) Vehicle operation. (2) Constituent determination. (i) Continuous sampling. (ii) Batch sampling. X 2 4 2 2 (iii) Combined sampling. (A) You may use continuous sampling for some constituents and batch sampling for others. (B) You may use continuous and batch sampling for a single constituent, with one being a redundant measurement, subject to the provisions of 40 CFR 1065.201. (d) Refer to subpart G of this part and the standard-setting part for calculations to determine g/mile emission rates. (e) You must use good engineering judgment for all aspects of testing under this part. While this part highlights several specific cases where good engineering judgment is especially relevant, the requirement to use good engineering judgment is not limited to those provisions where we specifically re-state this requirement. § 1066.20 Units of measure and overview of calculations. (a) System of units. (b) Units conversion. (1) 1 hp = 33,000 ft · lbf/min = 550 ft · lbf/s = 0.7457 kW. (2) 1 lbf = 32.174 ft · lbm/s 2 (3) 1 inch = 25.4 mm. (4) 1 mile = 1609.344 m. (5) For ideal gases, 1 µmol/mol = 1 ppm. (6) For ideal gases, 10 mmol/mol = 1%. (c) Temperature. (d) Absolute pressure. (e) Rounding. (f) Interpretation of ranges. (1) Whenever we specify a range by a single value and corresponding limit values above and below that value (such as X ±Y), target the associated control point to that single value (X). Examples of this type of range include “±10% of maximum pressure”, or “(30 ±10) kPa”. In these examples, you would target the maximum pressure or 30 kPa, respectively. (2) Whenever we specify a range by the interval between two values, you may target any associated control point to any value within that range. An example of this type of range is “(40 to 50) kPa”. (g) Scaling of specifications with respect to an applicable standard. § 1066.25 Recordkeeping. (a) The procedures in this part include various requirements to record data or other information. Refer to the standard-setting part and § 1066.695 regarding specific recordkeeping requirements. (b) You must promptly send us organized, written records in English if we ask for them. We may review them at any time. (c) We may waive specific reporting or recordkeeping requirements we determine to be unnecessary for the purposes of this part and the standard-setting part. Note that while we will generally keep the records required by this part, we are not obligated to keep records we determine to be unnecessary for us to keep. For example, while we require you to keep records for invalid tests so we may verify that your invalidation was appropriate, it is not necessary for us to keep records for our own invalid tests. Subpart B—Equipment, Measurement Instruments, Fuel, and Analytical Gas Specifications § 1066.101 Overview. (a) This subpart addresses equipment related to emission testing, as well as test fuels and analytical gases. (b) The provisions of 40 CFR part 1065 specify engine-based procedures for measuring emissions. Except as specified otherwise in this part, the provisions of 40 CFR part 1065 apply for testing required by this part as follows: (1) The provisions of 40 CFR part 1065, subpart B, describe equipment specifications for exhaust dilution and sampling systems; these specifications apply for testing under this part as described in § 1066.110. (2) The provisions of 40 CFR part 1065, subpart C, describe specifications for measurement instruments; these specifications apply for testing under this part as described in § 1066.120. (3) The provisions of 40 CFR part 1065, subpart D, describe specifications for measurement instrument calibrations and verifications; these specifications apply for testing under this part as described in § 1066.130. (4) The provisions of 40 CFR part 1065, subpart H, describe specifications for fuels, engine fluids, and analytical gases; these specifications apply for testing under this part as described in § 1066.145. (5) The provisions of 40 CFR part 1065, subpart I, describe specifications for testing with oxygenated fuels; these specifications apply for NMOG determination as described in § 1066.635. (c) The provisions of this subpart are intended to specify systems that can very accurately and precisely measure emissions from motor vehicles such as light-duty vehicles. To the extent that this level of accuracy or precision is not necessary for testing highway motorcycles or nonroad vehicles, we may waive or modify the specifications and requirements of this part for testing these other vehicles, consistent with good engineering judgment. For example, it may be appropriate to allow the use of a hydrokinetic dynamometer that is not able to meet all the performance specifications described in this subpart. § 1066.105 Ambient controls and vehicle cooling fans. (a) Ambient conditions. (b) General requirements for cooling fans. (c) Allowable cooling fans for vehicles at or below 14,000 pounds GVWR. (1) Cooling fan specifications for different test cycles are summarized as follows: (i) For the FTP test cycle, the allowable cooling fan configurations are described in paragraphs (c)(2) and (3) of this section. (ii) For the HFET test cycle, the allowable cooling fan configurations are described in paragraphs (c)(2) and (3) of this section. (iii) For the US06 test cycle, the allowable cooling fan configurations are described in paragraphs (c)(2) and (4) of this section. (iv) For the LA-92 test cycle, the allowable cooling fan configurations are described in paragraphs (c)(2) and (4) of this section. (v) For SC03 and AC17 test cycles, the allowable cooling fan configuration is described in paragraph (c)(5) of this section. (2) You may use a road-speed modulated fan system meeting the specifications of this paragraph (c)(2) for anything other than SC03 and AC17 testing. Use a road-speed modulated fan that achieves a linear speed of cooling air at the blower outlet that is within ±3.0 mi/hr (±1.3 m/s) of the corresponding roll speed when vehicle speeds are between 5 and 30 mi/hr, and within ±6.5 mi/hr (±2.9 m/s) of the corresponding roll speed at higher vehicle speeds; however you may limit the fan's maximum linear speed to 70 mi/hr. We recommend that the cooling fan have a minimum opening of 0.2 m 2 (i) Verify the air flow velocity for fan speeds corresponding to vehicle speeds of 20 and 40 mi/hr using an instrument that has an accuracy of ±2% of the measured air flow speed. (ii) For fans with rectangular outlets, divide the fan outlet into sections as shown in Figure 1 of this section. As illustrated by the “ + ” in the following figure, measure flow from the center of each section; do not measure the flow from the center section. (iii) For fans with circular outlets, divide the fan outlet into 8 equal sections as shown in Figure 2 of this section. As illustrated by the “ + ” in the following figure, measure flow on the radial centerline of each section, at a radius of two-thirds of the fan's total radius. (iv) Verify that the uniformity of the fan's axial flow is constant across the discharge area within a tolerance of ±4.0 mi/hr of the vehicle's speed at fan speeds corresponding to 20 mi/hr, and within ±8.0 mi/hr at fan speeds corresponding to 40 mi/hr. For example, at a vehicle speed of 20.2 mi/hr, axial flow at all locations denoted by the “+” across the discharge nozzle must be between 16.2 and 24.2 mi/hr. When measuring the axial air flow velocity, use good engineering judgment to determine the distance from the nozzle outlet at each point of the fan outlet grid. Use these values to calculate a mean air flow velocity across the discharge area at each speed setting. The instrument used to verify the air velocity must have an accuracy of ±2% of the measured air flow velocity. (v) Use a multi-axis flow meter or another method to verify that the fan's air flow perpendicular to the axial air flow is less than 15% of the axial air flow, consistent with good engineering judgment. Demonstrate this by comparing the perpendicular air flow velocity to the mean air flow velocities determined in paragraph (c)(2)(iv) of this section at vehicle speeds of 20 and 40 mi/hr. (3) You may use a fixed-speed fan with a maximum capacity up to 2.50 m 3 (4) You may use a fixed-speed fan with a maximum capacity up to 7.10 m 3 (5) For SC03 and AC17 testing, use a road-speed modulated fan with a minimum discharge area that is equal to or exceeds the vehicle's frontal inlet area. We recommend using a fan with a discharge area of 1.7 m 2 (i) Air flow volumes must be proportional to vehicle speed. Select a fan size that will produce a flow volume of approximately 45 m 3 (ii) Verify the uniformity of the fan's axial flow as described in paragraph (c)(2)(iv) of this section, except that you must measure the axial air flow velocity 60 cm from the nozzle outlet at each point of the discharge area grid. (iii) Use a multi-axis flow meter or another method to verify that the fan's air flow perpendicular to the axial air flow is less than 10% of the axial air flow, consistent with good engineering judgment. Demonstrate this by comparing the perpendicular air flow velocity to the mean air flow velocities determined in paragraph (c)(2)(iv) of this section at vehicle speeds of 20 and 40 mi/hr. (iv) In addition to the road-speed modulated fan, we may approve the use of one or more fixed-speed fans to provide proper cooling to represent in-use operation, but only up to a total of 2.50 m 3 (d) Allowable cooling fans for vehicles above 14,000 pounds GVWR. 2 3 [79 FR 23823, Apr. 28, 2014, as amended at 81 FR 74195, Oct. 25, 2016] § 1066.110 Equipment specifications for emission sampling systems. (a) This section specifies equipment related to emission testing, other than measurement instruments. This equipment includes dynamometers (described further in subpart C of this part) and various emission-sampling hardware. (b) The following equipment specifications apply for testing under this part: (1) Connect a vehicle's exhaust system to any dilution stage as follows: (i) Minimize lengths of laboratory exhaust tubing. You may use a total length of laboratory exhaust tubing up to 4 m without needing to heat or insulate the tubing. However, you may use a total length of laboratory exhaust tubing up to 10 m, or up to 15 m for samples not involving PM measurement, if you insulate and/or heat the tubing to minimize the temperature difference between the exhaust gas and the whole tubing wall over the course of the emission test. The laboratory exhaust tubing starts at the end of the vehicle's tailpipe and ends at the first sample point or the first dilution point. The laboratory exhaust tubing may include flexible sections, but we recommend that you limit the amount of flexible tubing to the extent practicable. For multiple-tailpipe configurations where the tailpipes combine into a single flow path for emission sampling, the start of the laboratory exhaust tubing may be taken at the last joint where the exhaust flow first becomes a single, combined flow. (ii) For vehicles above 14,000 pounds GVWR, you may shorten the tailpipe up to the outlet of the last aftertreatment device or silencer, whichever is furthest downstream. (iii) You may insulate or heat any laboratory exhaust tubing. (iv) Use laboratory exhaust tubing materials that are smooth-walled and not chemically reactive with exhaust constituents. (For purposes of this paragraph (b)(1), nominally smooth spiral-style and accordion-style flexible tubing are considered to be smooth-walled.) For measurements involving PM, tubing materials must also be electrically conductive. Stainless steel is an acceptable material for any testing. You may use short sections of nonconductive flexible tubing to connect a PM sampling system to the vehicle's tailpipe; use good engineering judgment to limit the amount of nonconductive surface area exposed to the vehicle's exhaust. (v) We recommend that you use laboratory exhaust tubing that has either a wall thickness of less than 2 mm or is air gap-insulated to minimize temperature differences between the wall and the exhaust. (vi) You must seal your system to the extent necessary to ensure that any remaining leaks do not affect your ability to demonstrate compliance with the applicable standards in this chapter. We recommend that you seal all known leaks. (vii) Electrically ground the entire exhaust system, with the exception of nonconductive flexible tubing, as allowed under paragraph (b)(1)(iv) of this section. (viii) For vehicles with multiple tailpipes, route the exhaust into a single flow. To ensure mixing of the multiple exhaust streams before emission sampling, we recommend a minimum Reynolds number, Re # Re # Re # Re # (2) Use equipment specifications in 40 CFR 1065.140 through 40 CFR 1065.190, except as follows: (i) For PM background measurement, the following provisions apply in addition to the provisions in 40 CFR 1065.140(b): (A) You need not measure PM background for every test. You may apply PM background correction for a single site or multiple sites using a moving-average background value as long as your background PM sample media (e.g., filters) were all made by the same manufacturer from the same material. Use good engineering judgment to determine how many background samples make up the moving average and how frequently to update those values. For example, you might take one background sample per week and average that sample into previous background values, maintaining five observations for each calculated average value. Background sampling time should be representative of the duration of the test interval to which the background correction is applied. (B) You may sample background PM from the dilution tunnel at any time before or after an emission test using the same sampling system used during the emission test. For this background sampling, the dilution tunnel blower must be turned on, the vehicle must be disconnected from the laboratory exhaust tubing, and the laboratory exhaust tubing must be capped. You may run this PM blank test in combination with the dilute exhaust flow verification (propane check) in 40 CFR 1065.341, as long as the exhaust tubing inlet to the CVS has a filter meeting the requirements of 40 CFR 1065.140(b)(3). (C) The duration of your background sample may be different than that of the test cycle in which you are applying the background correction, consistent with good engineering judgment. (D) Your PM background correction may not exceed 5 µg or 5% of the net PM mass expected at the standard, whichever is greater. (ii) The provisions of 40 CFR 1065.140(d)(2)(iv) do not apply. (iii) For PM samples, configure dilution systems using the following limits: (A) Control the dilution air temperature as described in 40 CFR 1065.140(e)(1), except that the temperature may be set to (15 to 52) °C. Use good engineering judgment to control PM sample temperature as required under 40 CFR 1065.140(e)(4). (B) Apply the provisions of this paragraph (b)(2)(iii)(B) instead of 40 CFR 1065.140(e)(2). Add dilution air to the raw exhaust such that the overall dilution factor of diluted exhaust to raw exhaust, as shown in Eq. 1066.610-2 or 1066.610-3, is within the range of (7:1 to 20:1). Compliance with this dilution factor range may be determined for an individual test interval or as a time-weighted average over the entire duty cycle as determined in Eq. 1066.610-4. The maximum dilution factor limit of 20:1 does not apply for hybrid electric vehicles (HEVs), since the dilution factor is infinite when the engine is off; however we strongly recommend that you stay under the specified maximum dilution factor limit when the engine is running. For partial-flow sampling systems, determine dilution factor using Eq. 1066.610-3. To determine the overall dilution factor for PM samples utilizing secondary dilution air, multiply the dilution factor from the CVS by the dilution ratio of secondary dilution air to primary diluted exhaust. (C) You may use a higher target filter face velocity as specified in 40 CFR 1065.170(c)(1)(vi), up to 140 cm/s, if you need to increase filter loading for PM measurement. (iv) In addition to the allowances in 40 CFR 1065.140(c)(6), you may heat the dilution air as described in paragraph (b)(2)(iii)(A) of this section to prevent or limit aqueous condensation. (v) If you choose to dilute the exhaust by using a remote mix tee, which dilutes the exhaust at the tailpipe, you may use the following provisions consistent with good engineering judgment, as long as they do not affect your ability to demonstrate compliance with the applicable standards in this chapter: (A) You may use smooth-walled flexible tubing (including accordion-style) in the dilution tunnel upstream of locations for flow measurement or gaseous emission measurement. (B) You may use smooth-walled electrically conductive flexible tubing in the dilution tunnel upstream of the location for PM emission measurements. (C) All inside surfaces upstream of emission sampling must be made of 300 series stainless steel or polymer-based materials. (D) Use good engineering judgment to ensure that the materials you choose do not cause significant loss of PM from your sample. (vi) Paragraph (b)(1)(vi) of this section applies instead of 40 CFR 1065.145(b). (vii) Vehicles other than HEVs that apply technology involving engine shutdown during idle may apply the sampling provisions of § 1066.501(c). (c) The following table summarizes the requirements of paragraph (b)(2) of this section: Table 1 of § 1066.110—Summary of Equipment Specifications From 40 CFR Part 1065, Subpart B, That Apply for Chassis Testing 40 CFR part 1065 Applicability for chassis testing under this part 40 CFR 1065.140 Use all except as noted: 40 CFR 1065.145 Use all except 40 CFR 1065.145(b). 40 CFR 1065.150 Use all. 40 CFR 1065.170 Use all except as noted: 40 CFR 1065.190 Use all. [79 FR 23823, Apr. 28, 2014, as amended at 81 FR 74196, Oct. 25, 2016; 88 FR 4708, Jan. 24, 2023] § 1066.120 Measurement instruments. The measurement instrument requirements in 40 CFR part 1065, subpart C, apply with the following exceptions: (a) The provisions of § 1066.125 apply instead of 40 CFR 1065.202. (b) The provisions of 40 CFR 1065.210 and 1065.295 do not apply. § 1066.125 Data updating, recording, and control. This section specifies criteria that your test system must meet for updating and recording data. It also specifies criteria for controlling the systems related to driver demand, the dynamometer, sampling equipment, and measurement instruments. (a) Read and record values and calculate mean values relative to a specified frequency as follows: (1) This paragraph (a)(1) applies where we specify a minimum command and control frequency that is greater than the minimum recording frequency, such as for sample flow rates from a CVS that does not have a heat exchanger. For these measurements, the rate at which you read and interpret the signal must be at least as frequent as the minimum command and control frequency. You may record values at the same frequency, or you may record them as mean values, as long as the frequency of the mean values meets the minimum recording frequency. You must use all read values, either by recording them or using them to calculate mean values. For example, if your system reads and controls the sample flow rate at 10 Hz, you may record these values at 10 Hz, record them at 5 Hz by averaging pairs of consecutive points together, or record them at 1 Hz by averaging ten consecutive points together. (2) For all other measured values covered by this section, you may record the values instantaneously or as mean values, consistent with good engineering judgment. (3) You may not use rolling averages of measured values where a given measured value is included in more than one recorded mean value. (b) Use data acquisition and control systems that can command, control, and record at the following minimum frequencies: Table 1 of § 1066.125—Data Recording and Control Minimum Frequencies Applicable section Measured values Minimum command and control frequency a Minimum recording frequency b c § 1066.310 Vehicle speed 10 Hz. § 1066.425 Continuous concentrations of raw or dilute analyzers 1 Hz. § 1066.425 Power analyzer 1 Hz. § 1066.425 Bag concentrations of raw or dilute analyzers 1 mean value per test interval. 40 CFR 1065.545 Diluted exhaust flow rate from a CVS with a heat exchanger upstream of the flow measurement 1 Hz. 40 CFR 1065.545 Diluted exhaust flow rate from a CVS without a heat exchanger upstream of the flow measurement 5 Hz 1 Hz means. 40 CFR 1065.545 Dilution air flow if actively controlled (for example, a partial-flow PM sampling system) d 5 Hz 1 Hz means. 40 CFR 1065.545 Sample flow from a CVS that has a heat exchanger 1 Hz 1 Hz. 40 CFR 1065.545 Sample flow from a CVS that does not have a heat exchanger 5 Hz 1 Hz means. § 1066.420 Ambient temperature 1 Hz. e § 1066.420 Ambient humidity 1 Hz. e § 1066.420 Heated sample system temperatures, including PM filter face 1 Hz. a b c d e [79 FR 23823, Apr. 28, 2014, as amended at 80 FR 9120, Feb. 19, 2015] § 1066.130 Measurement instrument calibrations and verifications. The measurement instrument calibration and verification requirements in 40 CFR part 1065, subpart D, apply with the following exceptions: (a) The calibration and verification provisions of 40 CFR 1065.303 do not apply for engine speed, torque, fuel rate, or intake air flow. (b) The linearity verification provisions of 40 CFR 1065.307 do not apply for engine speed, torque, fuel rate, or intake air flow. Section 1066.135 specifies additional linearity verification provisions that apply specifically for chassis testing. (c) The provisions of § 1066.220 apply instead 40 CFR 1065.310. (d) The provisions of 40 CFR 1065.320, 1065.325, and 1065.395 do not apply. (e) If you are measuring flow volumetrically (rather than measuring based on molar values), the provisions of § 1066.140 apply instead of 40 CFR 1065.340. (f) The provisions of § 1066.150 apply instead 40 CFR 1065.350(c), 1065.355(c), 1065.370(c), and 1065.375(c). (g) Table 1 of this section summarizes the required and recommended calibrations and verifications that are unique to testing under this part and indicates when these must be performed. Perform other required or recommended calibrations and verifications as described in 40 CFR 1065.303, with the exceptions noted in this section. Table 1 follows: Table 1 of § 1066.130—Summary of Required Calibrations and Verifications Type of calibration or verification Minimum frequency a 40 CFR 1065.307: Linearity verification The linearity verifications from 40 CFR part 1065 do not apply under this part for engine speed, torque, fuel rate, or intake air flow; the linearity verification described in § 1066.135 applies for the following measurements: 40 CFR 1065.310: Torque This calibration does not apply for testing under this part; see § 1066.220. 40 CFR 1065.320: Fuel flow This calibration does not apply for testing under this part. 40 CFR 1065.325: Intake flow This calibration does not apply for testing under this part. 40 CFR 1065.340: CVS calibration This calibration does not apply for CVS flow meters calibrated volumetrically as described in § 1066.140. 40 CFR 1065.345: Vacuum leak Required upon initial installation of the sampling system; recommended within 35 days before the start of an emissions test and after maintenance such as pre-filter changes. 40 CFR 1065.350(c), 1065.355(c), 1065.370(c), and 1065.375(c) These provisions do not apply for testing under this part; see § 1066.150. 40 CFR 1065.395: Inertial PM balance and weighing These verifications do not apply for testing under this part. a § 1066.135 Linearity verification. This section describes requirements for linearity verification that are unique to testing under this part. (Note: See the definition of “linearity” in 40 CFR 1065.1001, where we explain that linearity means the degree to which measured values agree with respective reference values and that the term “linearity” is not used to refer to the shape of a measurement instrument's unprocessed response curve.) Perform other required or recommended calibrations and verifications as described in 40 CFR 1065.307, with the exceptions noted in this section. (a) For gas analyzer linearity, use one of the following options: (1) Use instrument manufacturer recommendations and good engineering judgment to select at least ten reference values, y refi (2) Use the linearity requirements of 40 CFR 1065.307, except for CO 2 (b) For dilution air, diluted exhaust, and raw exhaust sample flow, use a reference flow meter with a blower or pump to simulate flow rates. Use a restrictor, diverter valve, variable-speed blower, or variable-speed pump to control the range of flow rates. Use the reference meter's response for the reference values. (1) Reference flow meters. (2) Reference flow values. Q refi Q ref (3) Linearity criteria. x min a 1 a 0 Q max a 1 SEE Q max r 2 (c) Perform linearity verifications for the following temperature measurements instead of those specified at 40 CFR 1065.307(e)(7): (1) Test cell ambient air. (2) Dilution air for PM sampling, including CVS, double-dilution, and partial-flow systems. (3) PM sample. (4) Chiller sample, for gaseous sampling systems that use thermal chillers to dry samples, and that use chiller temperature to calculate dewpoint at the chiller outlet. For testing, if you choose to use the high alarm temperature setpoint for the chiller temperature as a constant value in determining the amount of water removed from the emission sample, you may verify the accuracy of the high alarm temperature setpoint using good engineering judgment without following the linearity verification for chiller temperature. We recommend that you input a simulated reference temperature signal below the alarm setpoint, increase this signal until the high alarm trips, and verify that the alarm setpoint value is no less than 2 °C below the reference value at the trip point. (5) CVS flow meter inlet temperature. (d) Perform linearity verifications for the following pressure measurements instead of those specified at 40 CFR 1065.307(e)(8): (1) Raw exhaust static pressure control. (2) Barometric pressure. (3) CVS flow meter inlet pressure. (4) Sample dryer, for gaseous sampling systems that use either osmotic-membrane dryers or thermal chillers to dry samples. For your testing, if you choose to use a low alarm pressure setpoint for the sample dryer pressure as a constant value in determining the amount of water removed from the emission sample, you may verify the accuracy of the low alarm pressure setpoint using good engineering judgment without following the linearity verification for sample dryer pressure. We recommend that you input a reference pressure signal above the alarm setpoint, decrease this signal until the low alarm trips, and verify that the alarm setpoint value is no more than 4 kPa above the reference value at the trip point. (e) When following procedures or practices that we incorporate by reference in § 1066.1010, you must meet the linearity requirements given by the procedure or practice for any analytical instruments not covered under 40 CFR 1065.307, such as GC-FID or HPLC. [79 FR 23823, Apr. 28, 2014, as amended at 81 FR 74197, Oct. 25, 2016; 86 FR 34581, June 29, 2021] § 1066.140 Diluted exhaust flow calibration. (a) Overview. (b) Scope and frequency. (c) Ex-situ CFV and SSV calibration. (d) Reference flow meter. (e) Configuration. (f) PDP calibration. (1) Connect the system as shown in Figure 1 of this section. (2) Leaks between the calibration flow meter and the PDP must be less than 0.3% of the total flow at the lowest calibrated flow point; for example, at the highest restriction and lowest PDP-speed point. (3) While the PDP operates, maintain a constant temperature at the PDP inlet within ±2% of the mean absolute inlet temperature, T in (4) Set the PDP speed to the first speed point at which you intend to calibrate. (5) Set the variable restrictor to its wide-open position. (6) Operate the PDP for at least 3 min to stabilize the system. Continue operating the PDP and record the mean values of at least 30 seconds of sampled data of each of the following quantities: (i) The mean flow rate of the reference flow meter, V ref V ref (ii) The mean temperature at the PDP inlet, T in (iii) The mean static absolute pressure at the PDP inlet, P in (iv) The mean static absolute pressure at the PDP outlet, P out (v) The mean PDP speed, f nPDP (7) Incrementally close the restrictor valve to decrease the absolute pressure at the inlet to the PDP, P in (8) Repeat the steps in paragraphs (f)(6) and (7) of this section to record data at a minimum of six restrictor positions ranging from the wide-open restrictor position to the minimum expected pressure at the PDP inlet or the maximum expected differential (outlet minus inlet) pressure across the PDP during testing. (9) Calibrate the PDP by using the collected data and the equations in § 1066.625(a). (10) Repeat the steps in paragraphs (f)(6) through (9) of this section for each speed at which you operate the PDP. (11) Use the equations in § 1066.630(a) to determine the PDP flow equation for emission testing. (12) Verify the calibration by performing a CVS verification (i.e., propane check) as described in 40 CFR 1065.341. (13) During emission testing ensure that the PDP is not operated either below the lowest inlet pressure point or above the highest differential pressure point in the calibration data. (g) SSV calibration. C d (1) Configure your calibration system as shown in Figure 1 of this section. (2) Verify that any leaks between the calibration flow meter and the SSV are less than 0.3% of the total flow at the highest restriction. (3) Start the blower downstream of the SSV. (4) While the SSV operates, maintain a constant temperature at the SSV inlet within ±2% of the mean absolute inlet temperature, T in (5) Set the variable restrictor or variable-speed blower to a flow rate greater than the greatest flow rate expected during testing. You may not extrapolate flow rates beyond calibrated values, so we recommend that you make sure the Reynolds number, Re # Re # (6) Operate the SSV for at least 3 min to stabilize the system. Continue operating the SSV and record the mean of at least 30 seconds of sampled data of each of the following quantities: (i) The mean flow rate of the reference flow meter, V ref V ref (ii) The mean temperature at the venturi inlet, T in (iii) The mean static absolute pressure at the venturi inlet, p in (iv) Mean static differential pressure between the static pressure at the venturi inlet and the static pressure at the venturi throat, Δ p ssv (7) Incrementally close the restrictor valve or decrease the blower speed to decrease the flow rate. (8) Repeat the steps in paragraphs (g)(6) and (7) of this section to record data at a minimum of ten flow rates. (9) Determine an equation to quantify C d Re # C d Re # (10) Verify the calibration by performing a CVS verification (i.e., propane check) as described in 40 CFR 1065.341 using the new C d Re # (11) Use the SSV only between the minimum and maximum calibrated Re # Re # (12) Use the equations in § 1066.630(b) to determine SSV flow during a test. (h) CFV calibration. K v r (1) Configure your calibration system as shown in Figure 1 of this section. (2) Verify that any leaks between the calibration flow meter and the CFV are less than 0.3% of the total flow at the highest restriction. (3) Start the blower downstream of the CFV. (4) While the CFV operates, maintain a constant temperature at the CFV inlet within ±2% of the mean absolute inlet temperature, T in (5) Set the variable restrictor to its wide-open position. Instead of a variable restrictor, you may alternately vary the pressure downstream of the CFV by varying blower speed or by introducing a controlled leak. Note that some blowers have limitations on nonloaded conditions. (6) Operate the CFV for at least 3 min to stabilize the system. Continue operating the CFV and record the mean values of at least 30 seconds of sampled data of each of the following quantities: (i) The mean flow rate of the reference flow meter, V ref V ref (ii) The mean temperature at the venturi inlet, T in (iii) The mean static absolute pressure at the venturi inlet, p in (iv) The mean static differential pressure between the CFV inlet and the CFV outlet, Δ p CFV (7) Incrementally close the restrictor valve or decrease the downstream pressure to decrease the differential pressure across the CFV, Δp CFV (8) Repeat the steps in paragraphs (h)(6) and (7) of this section to record mean data at a minimum of ten restrictor positions, such that you test the fullest practical range of Δ p CFV (9) Determine K v r (10) Use K v r (11) Verify the calibration by performing a CVS verification (i.e., propane check) as described in 40 CFR 1065.341. (12) If your CVS is configured to operate multiple CFVs in parallel, calibrate your CVS using one of the following methods: (i) Calibrate every combination of CFVs according to this section and § 1066.625(c). Refer to § 1066.630(c) for instructions on calculating flow rates for this option. (ii) Calibrate each CFV according to this section and § 1066.625. Refer to § 1066.630 for instructions on calculating flow rates for this option. (i) Ultrasonic flow meter calibration. [79 FR 23823, Apr. 28, 2014, as amended at 81 FR 74197, Oct. 25, 2016] § 1066.145 Test fuel, engine fluids, analytical gases, and other calibration standards. (a) Test fuel. (b) Lubricating oil. (c) Coolant. (d) Analytical gases. (e) Mass standards. § 1066.150 Analyzer interference and quench verification limit. Analyzers must meet the interference and quench verification limits in the following table on the lowest, or most representative, instrument range that will be used during emission testing, instead of those specified in 40 CFR part 1065, subpart D: Table 1 of § 1066.150—Analyzer Interference and Quench Verification Limits Verification Limit 40 CFR 1065.350 ±2% of full scale. 40 CFR 1065.355 ±2% of full scale. 40 CFR 1065.370 ±2% of full scale. 40 CFR 1065.375 ±2% of the flow-weighted mean concentration of N 2 Subpart C—Dynamometer Specifications § 1066.201 Dynamometer overview. This subpart addresses chassis dynamometers and related equipment. § 1066.210 Dynamometers. (a) General requirements. (b) Accuracy and precision. (1) For dynamometer testing of vehicles at or below 20,000 pounds GVWR, the dynamometer force-measurement system must be capable of indicating force readings during a test to a resolution of ±0.05% of the maximum load-cell force simulated by the dynamometer or ±9.8 N (±2.2 lbf), whichever is greater. (2) For dynamometer testing of vehicles above 20,000 pounds GVWR, the force-measurement system must be capable of indicating force readings during a test to a resolution of ±0.05% of the maximum load-cell force simulated by the dynamometer or ±39.2 N (±8.8 lbf), whichever is greater. (c) Test cycles. (d) Component requirements. (1) The nominal roll diameter must be 120 cm or greater. The dynamometer must have an independent drive roll for each drive axle as tested under § 1066.410(g), except that two drive axles may share a single drive roll. Use good engineering judgment to ensure that the dynamometer roll diameter is large enough to provide sufficient tire-roll contact area to avoid tire overheating and power losses from tire-roll slippage. (2) Measure and record force and speed at 10 Hz or faster. You may convert measured values to 1-Hz, 2-Hz, or 5-Hz values before your calculations, using good engineering judgment. (3) The load applied by the dynamometer simulates forces acting on the vehicle during normal driving according to the following equation: Where: FR i i A G i B v v i−1 i C 2 2 2 M e t t i−1 i M a g 2 (4) We recommend that a dynamometer capable of testing vehicles at or below 20,000 pounds GVWR be designed to apply an actual road-load force within ±1% or ±9.8 N (±2.2 lbf) of the reference value, whichever is greater. Note that slightly higher errors may be expected during highly transient operation for vehicles above 8,500 pounds GVWR. (e) Dynamometer manufacturer instructions. [79 FR 23823, Apr. 28, 2014, as amended at 81 FR 74198, Oct. 25, 2016; 86 FR 34581, June 29, 2021] § 1066.215 Summary of verification procedures for chassis dynamometers. (a) Overview. (b) Scope and frequency. Table 1 of § 1066.215—Summary of Required Dynamometer Verifications Type of verification Minimum frequency a § 1066.220: Linearity verification Speed: Upon initial installation, within 370 days before testing, and after major maintenance. Torque (load): Upon initial installation and after major maintenance. § 1066.225: Roll runout and diameter verification Upon initial installation and after major maintenance. § 1066.230: Time verification Upon initial installation and after major maintenance. § 1066.235: Speed measurement verification Upon initial installation, within 370 days before testing, and after major maintenance. § 1066.240: Torque (load) transducer verification Upon initial installation, within 7 days of testing, and after major maintenance. § 1066.245: Response time verification Upon initial installation, within 370 days before testing, and after major maintenance. § 1066.250: Base inertia verification Upon initial installation and after major maintenance. § 1066.255: Parasitic loss verification Upon initial installation, after major maintenance, and upon failure of a verification in § 1066.270 or § 1066.275. § 1066.260: Parasitic friction compensation verification Upon initial installation, after major maintenance, and upon failure of a verification in § 1066.270 or § 1066.275. § 1066.265: Acceleration and deceleration verification Upon initial installation and after major maintenance. § 1066.270: Unloaded coastdown verification Upon initial installation, within 7 days of testing, and after major maintenance. § 1066.275 Dynamometer readiness verification Upon initial installation, within 1 day before testing, and after major maintenance. a (c) Automated dynamometer verifications and calibrations. (d) Sequence of verifications and calibrations. (e) Corrections. § 1066.220 Linearity verification for chassis dynamometer systems. (a) Scope and frequency. (b) Performance requirements. (c) Procedure. (1) In this paragraph (c), the letter “y” denotes a generic measured quantity, the superscript over-bar denotes an arithmetic mean (such as y ref (2) Operate the dynamometer system at the specified operating conditions. This may include any specified adjustment or periodic calibration of the dynamometer system. (3) Set dynamometer speed and torque to zero. (4) Verify the dynamometer speed or torque signal based on the dynamometer manufacturer's recommendations. (5) After verification, check for zero speed and torque. Use good engineering judgment to determine whether or not to rezero or re-verify speed and torque before continuing. (6) For both speed and torque, use the dynamometer manufacturer's recommendations and good engineering judgment to select reference values, y refi (7) Use the dynamometer manufacturer's recommendations and good engineering judgment to select the order in which you will introduce the series of reference values. For example, you may select the reference values randomly to avoid correlation with previous measurements and to avoid the influence of hysteresis; you may select reference values in ascending or descending order to avoid long settling times of reference signals; or you may select values to ascend and then descend to incorporate the effects of any instrument hysteresis into the linearity verification. (8) Set the dynamometer to operate at a reference condition. (9) Allow time for the dynamometer to stabilize while it measures the reference values. (10) At a recording frequency of at least 1 Hz, measure speed and torque values for 30 seconds and record the arithmetic mean of the recorded values,. Refer to 40 CFR 1065.602 for an example of calculating an arithmetic mean. (11) Repeat the steps in paragraphs (c)(8) though (10) of this section until you measure speeds and torques at each of the reference settings. (12) Use the arithmetic means, y i y refi y refi y i Table 1 of § 1066.220—Dynamometer Measurement Systems that Require Linearity Verifications Measurement system Quantity Linearity criteria | y min a 1 a 0 a 1 SEE r 2 Speed n ≤0.05% · n max 0.98-1.02 ≤2% · n max ≥0.990 Torque (load) T ≤1% · T max 0.99-1.01 ≤1% · T max ≥0.990 (d) Reference signals. [79 FR 23823, Apr. 28, 2014, as amended at 88 FR 4708, Jan. 24, 2023] § 1066.225 Roll runout and diameter verification procedure. (a) Overview. (b) Scope and frequency. (c) Roll runout procedure. (1) Perform this verification with laboratory and dynamometer temperatures stable and at equilibrium. Release the roll brake and shut off power to the dynamometer. Remove any dirt, rubber, rust, and debris from the roll surface. Mark measurement locations on the roll surface using a marker. Mark the roll at a minimum of four equally spaced locations across the roll width; we recommend taking measurements every 150 mm across the roll. Secure the marker to the deck plate adjacent to the roll surface and slowly rotate the roll to mark a clear line around the roll circumference. Repeat this process for all measurement locations. (2) Measure roll runout using an indicator with a probe that allows for measuring the position of the roll surface relative to the roll centerline as it turns through a complete revolution. The indicator must have some means of being securely mounted adjacent to the roll. The indicator must have sufficient range to measure roll runout at all points, with a minimum accuracy of ±0.025 mm. Calibrate the indicator according to the instrument manufacturer's instructions. (3) Position the indicator adjacent to the roll surface at the desired measurement location. Position the shaft of the indicator perpendicular to the roll such that the point of the indicator is slightly touching the surface of the roll and can move freely through a full rotation of the roll. Zero the indicator according to the instrument manufacturer's instructions. Avoid distortion of the runout measurement from the weight of a person standing on or near the mounted dial indicator. (4) Slowly turn the roll through a complete rotation and record the maximum and minimum values from the indicator. Calculate runout as the difference between these maximum and minimum values. (5) Repeat the steps in paragraphs (c)(3) and (4) of this section for all measurement locations. (6) The roll runout must be less than 0.254 mm (0.0100 inches) at all measurement locations. (d) Diameter procedure. (1) Prepare the laboratory and the dynamometer as specified in paragraph (c)(1) of this section. (2) Measure roll diameter using a Pi Tape®. Orient the Pi Tape® to the marker line at the desired measurement location with the Pi Tape® hook pointed outward. Temporarily secure the Pi Tape® to the roll near the hook end with adhesive tape. Slowly turn the roll, wrapping the Pi Tape® around the roll surface. Ensure that the Pi Tape® is flat and adjacent to the marker line around the full circumference of the roll. Attach a 2.26-kg weight to the hook of the Pi Tape® and position the roll so that the weight dangles freely. Remove the adhesive tape without disturbing the orientation or alignment of the Pi Tape®. (3) Overlap the gage member and the vernier scale ends of the Pi Tape® to read the diameter measurement to the nearest 0.01 mm. Follow the manufacturer's recommendation to correct the measurement to 20 °C, if applicable. (4) Repeat the steps in paragraphs (d)(2) and (3) of this section for all measurement locations. (5) The measured roll diameter must be within ±0.254 mm of the specified nominal value at all measurement locations. You may revise the nominal value to meet this specification, as long as you use the corrected nominal value for all calculations in this subpart. § 1066.230 Time verification procedure. (a) Overview. (b) Scope and frequency. (c) Procedure. (1) WWV method. (i) Contact station WWV by telephone by dialing (303) 499-7111 and listen for the time announcement. Verify that the trigger started the dynamometer timer. Use good engineering judgment to minimize error in receiving the time and frequency signal. (ii) After at least 1000 seconds, re-dial station WWV and listen for the time announcement. Verify that the trigger stopped the dynamometer timer. (iii) Compare the measured elapsed time, y act y ref y error (2) Ramping method. (i) Set up a signal generator to output a marker voltage at the peak of each ramp to trigger the dynamometer timing circuit. Output the designated marker voltage to start the verification period. (ii) After at least 1000 seconds, output the designated marker voltage to end the verification period. (iii) Compare the measured elapsed time between marker signals, y act y ref y error (3) Dynamometer coastdown method. (i) Generate upper and lower speed values to trigger the start and stop functions of the coastdown timer circuit. Use the signal generator to start the verification period. (ii) After at least 1000 seconds, use the signal generator to end the verification period. (iii) Compare the measured elapsed time between trigger signals, y act y ref y error (d) Performance evaluation. § 1066.235 Speed verification procedure. (a) Overview. (b) Scope and frequency. (c) Procedure. (1) Pulse method. (i) Set the dynamometer to speed-control mode. Set the dynamometer speed to a value of approximately 4.5 m/s (10 mi/hr); record the output of the frequency counter after 10 seconds. Determine the roll speed, v act Where: f d roll n Example: f −1 d roll v act (ii) Repeat the steps in paragraph (c)(1)(i) of this section for the maximum speed expected during testing and at least two additional evenly spaced speed points between the starting speed and the maximum speed point. (iii) Compare the calculated roll speed, v act v ref v error Example: v act v ref v error = (2) Frequency method. (i) Set the dynamometer to speed-control mode. Set the dynamometer speed to a speed value of approximately 4.5 m/s (10 mi/hr). Tune the stroboscope or photo tachometer until the signal matches the dynamometer roll speed. Record the frequency. Determine the roll speed, y act f. (ii) Repeat the steps in paragraph (c)(2)(i) of this section for the maximum speed expected during testing and at least two additional evenly spaced speed points between the starting speed and the maximum speed point. (iii) Compare the calculated roll speed, v act v ref y error (d) Performance evaluation. [79 FR 23823, Apr. 28, 2014, as amended at 80 FR 9120, Feb. 19, 2015; 81 FR 74199, Oct. 25, 2016] § 1066.240 Torque transducer verification. Verify torque-measurement systems by performing the verifications described in §§ 1066.270 and 1066.275. § 1066.245 Response time verification. (a) Overview. (b) Scope and frequency. (c) Procedure. t s [79 FR 23823, Apr. 28, 2014, as amended at 81 FR 74199, Oct. 25, 2016] § 1066.250 Base inertia verification. (a) Overview. (b) Scope and frequency. (c) Procedure. (1) Warm up the dynamometer according to the dynamometer manufacturer's instructions. Set the dynamometer's road-load inertia to zero, turning off any electrical simulation of road load and inertia so that the base inertia of the dynamometer is the only inertia present. Motor the rolls to 5 mi/hr. Apply a constant force to accelerate the roll at a nominal rate of 1 (mi/hr)/s. Measure the elapsed time to accelerate from 10 to 40 mi/hr, noting the corresponding speed and time points to the nearest 0.01 mi/hr and 0.01 s. Also determine mean force over the measurement interval. (2) Starting from a steady roll speed of 45 mi/hr, apply a constant force to the roll to decelerate the roll at a nominal rate of 1 mi/hr/s. Measure the elapsed time to decelerate from 40 to 10 mi/hr, noting the corresponding speed and time points to the nearest 0.01 mi/hr and 0.01 s. Also determine mean force over the measurement interval. (3) Repeat the steps in paragraphs (c)(1) and (2) of this section for a total of five sets of results at the nominal acceleration rate and the nominal deceleration rate. (4) Use good engineering judgment to select two additional acceleration and deceleration rate pairs that cover the middle and upper rates expected during testing. Repeat the steps in paragraphs (c)(1) through (3) of this section at each of these additional acceleration and deceleration rates. (5) Determine the base inertia, I b, Where: F v final v init Δ t Example: F 2 v final v init Δ t I b (6) Calculate the base inertia error, I berror I b I bref Example: I bref I bact (7) Determine the base inertia mean value i b i b (8) Calculate the inertia error for the final base inertia mean value from paragraph (c)(7) of this section. Use Eq. 1066.250-2, substituting the final base inertia mean value from paragraph (c)(7) of this section for the individual base inertia. (d) Performance evaluation. (1) All base inertia errors determined under paragraph (c)(6) of this section may not exceed ±1.0%. (2) The inertia error for the final base inertia mean value determined under paragraph (c)(8) of this section may not exceed ±0.20%. [79 FR 23823, Apr. 28, 2014, as amended at 81 FR 74199, Oct. 25, 2016] § 1066.255 Parasitic loss verification. (a) Overview. (b) Scope and frequency. (c) Procedure. (d) Performance evaluation. [79 FR 23823, Apr. 28, 2014, as amended at 80 FR 9120, Feb. 19, 2015; 86 FR 34581, June 29, 2021] § 1066.260 Parasitic friction compensation evaluation. (a) Overview. (b) Scope and frequency. (c) Procedure. (1) Warm up the dynamometer as specified by the dynamometer manufacturer. (2) Perform a torque verification as specified by the dynamometer manufacturer. For torque verifications relying on shunt procedures, if the results do not conform to specifications, recalibrate the dynamometer using NIST-traceable standards as appropriate until the dynamometer passes the torque verification. Do not change the dynamometer's base inertia to pass the torque verification. (3) Set the dynamometer inertia to the base inertia with the road-load coefficients A, B, and C set to 0. Set the dynamometer to speed-control mode with a target speed of 50 mi/hr or a higher speed recommended by the dynamometer manufacturer. Once the speed stabilizes at the target speed, switch the dynamometer from speed-control to torque-control and allow the roll to coast for 60 seconds. Record the initial and final speeds and the corresponding start and stop times. If friction compensation is executed perfectly, there will be no change in speed during the measurement interval. (4) Calculate the power equivalent of friction compensation error, FC error Where: I t v init v final Example: I 2 t v init v final FC error (5) The friction compensation error may not exceed ±0.15 hp for dynamometers capable of testing vehicles at or below 20,000 pounds GVWR, or ±0.6 hp for dynamometers not capable of testing vehicles at or below 20,000 pounds GVWR. [79 FR 23823, Apr. 28, 2014, as amended at 81 FR 74200, Oct. 25, 2016; 86 FR 34581, June 29, 2021] § 1066.265 Acceleration and deceleration verification. (a) Overview. (b) Scope and frequency. (c) Verification of acceleration and deceleration rates. (1) Set up start and stop frequencies specific to your dynamometer by identifying the roll-revolution frequency, f Where: v n d roll (2) Program the dynamometer to accelerate the roll at a nominal rate of 1 mi/hr/s from 10 mi/hr to 40 mi/hr. Measure the elapsed time to reach the target speed, to the nearest 0.01 s. Repeat this measurement for a total of five runs. Determine the actual acceleration rate for each run, a act Where: a act v final v init t v init v final Example: v final v init t a act (3) Program the dynamometer to decelerate the roll at a nominal rate of 1 (mi/hr)/s from 40 mi/hr to 10 mi/hr. Measure the elapsed time to reach the target speed, to the nearest 0.01 s. Repeat this measurement for a total of five runs. Determine the actual acceleration rate, a act, (4) Repeat the steps in paragraphs (c)(2) and (3) of this section for additional acceleration and deceleration rates in 1 (mi/hr)/s increments up to and including one increment above the maximum acceleration rate expected during testing. Average the five repeat runs to calculate a mean acceleration rate, a act (5) Compare each mean acceleration rate, a act a ref a error Example: a act a ref a error (d) Verification of forces for controlling acceleration and deceleration. (1) Calculate the force setting, F Where: I b 2 a 2 Example: I b 2 a 2 F F (2) Set the dynamometer to road-load mode and program it with a calculated force to accelerate the roll at a nominal rate of 1 (mi/hr)/s from 10 mi/hr to 40 mi/hr. Measure the elapsed time to reach the target speed, to the nearest 0.01 s. Repeat this measurement for a total of five runs. Determine the actual acceleration rate, a act a act (3) Repeat the steps in paragraph (d)(2) of this section for additional acceleration and deceleration rates as specified in paragraph (c)(4) of this section. (4) Compare each mean acceleration rate, a act a ref a error (e) Performance evaluation. [79 FR 23823, Apr. 28, 2014, as amended at 81 FR 74200, Oct. 25, 2016; 86 FR 34582, June 29, 2021] § 1066.270 Unloaded coastdown verification. (a) Overview. (b) Scope and frequency. (c) Procedure. (1) Warm up the dynamometer as specified by the dynamometer manufacturer. (2) With the dynamometer in coastdown mode, set the dynamometer inertia for the smallest vehicle weight that you expect to test and set A, B, and C road-load coefficients to values typical of those used during testing. Program the dynamometer to coast down over the dynamometer operational speed range (typically from a speed of 80 mi/hr through a minimum speed at or below 10 mi/hr). Perform at least one coastdown run over this speed range, collecting data over each 10 mi/hr interval. (3) Repeat the steps in paragraph (c)(2) of this section with the dynamometer inertia and road-load coefficients set for the largest vehicle weight that you expect to test. (4) Determine the mean coastdown force, F Where: F I 2 v init v final t Example: I 2 v init v final t F (5) Calculate the target value of coastdown force, F ref (6) Compare the mean value of the coastdown force measured for each speed interval and inertia setting, F act F ref F error Example: F ref F act F error (d) Performance evaluation. (1) For vehicles at or below 20,000 pounds GVWR, the maximum allowable error, F errormax Example: F ref F errormax (2) For vehicles above 20,000 pounds GVWR, the maximum allowable error, F errormax (e) Remedy for nonconforming dynamometers. [79 FR 23823, Apr. 28, 2014, as amended at 80 FR 9120, Feb. 19, 2015; 81 FR 74201, Oct. 25, 2016; 86 FR 34582, June 29, 2021] § 1066.275 Daily dynamometer readiness verification. (a) Overview. (b) Scope and frequency. (c) Procedure. (1) With the dynamometer in coastdown mode, set the dynamometer inertia to the base inertia with the road-load coefficient A set to 20 lbf (or a force that results in a coastdown time of less than 10 minutes) and coefficients B and C set to 0. Program the dynamometer to coast down for one 10 mi/hr interval from 55 mi/hr down to 45 mi/hr. If your dynamometer is not capable of performing one discrete coastdown, then coast down with preset 10 mi/hr intervals that include a 55 mi/hr to 45 mi/hr interval. (2) Perform the coastdown. (3) Determine the coastdown force and coastdown force error using Eqs. 1066.270-1 and 1066.270-2. (d) Performance evaluation. (1) For vehicles at or below 20,000 pounds GVWR, 1.0% or the value determined from Eq. 1066.270-3, whichever is greater. (2) For vehicles above 20,000 pounds GVWR, 1.0% or the value determined from Eq. 1066.270-3 (substituting 8.8 lbf for 2.2 lbf), whichever is greater. (e) Remedy for nonconforming dynamometers. [79 FR 23823, Apr. 28, 2014, as amended at 81 FR 74201, Oct. 25, 2016; 86 FR 34582, June 29, 2021] § 1066.290 Verification of speed accuracy for the driver's aid. Use good engineering judgment to provide a driver's aid that facilitates compliance with the requirements of § 1066.425. Verify the speed accuracy of the driver's aid as described in § 1066.235. Subpart D—Coastdown § 1066.301 Overview of road-load determination procedures. Vehicle testing on a chassis dynamometer involves simulating the road-load force, which is the sum of forces acting on a vehicle from aerodynamic drag, tire rolling resistance, driveline losses, and other effects of friction. Determine dynamometer settings to simulate road-load force in two stages. First, perform a road-load force specification by characterizing on-road operation. Second, perform a road-load derivation to determine the appropriate dynamometer load settings to simulate the road-load force specification from the on-road test. (a) The procedures described in this subpart are used to determine the road-load target coefficients (A, B, and C) for the simulated road-load equation in § 1066.210(d)(3). (b) The general procedure for determining road-load force is performing coastdown tests and calculating road-load coefficients. This procedure is described in SAE J1263 and SAE J2263 (incorporated by reference, see § 1066.1010). Continued testing based on the 2008 version of SAE J2263 is optional, except that it is no longer available for testing starting with model year 2026. This subpart specifies certain deviations from those procedures for certain applications. (c) Use good engineering judgment for all aspects of road-load determination. For example, minimize the effects of grade by performing coastdown testing on reasonably level surfaces and determining coefficients based on average values from vehicle operation in opposite directions over the course. [80 FR 9121, Feb. 19, 2015, as amended at 81 FR 74201, Oct. 25, 2016; 88 FR 4708, Jan. 24, 2023; 89 FR 28211, Apr. 18, 2024] § 1066.305 Procedures for specifying road-load forces for motor vehicles at or below 14,000 pounds GVWR. (a) For motor vehicles at or below 14,000 pounds GVWR, develop representative road-load coefficients to characterize each vehicle covered by a certificate of conformity. Calculate road-load coefficients by performing coastdown tests using the provisions of SAE J1263 and SAE J2263 (incorporated by reference, see § 1066.1010). This protocol establishes a procedure for determination of vehicle road load force for speeds between 115 and 15 km/hr (71.5 and 9.3 mi/hr); the final result is a model of road-load force (as a function of speed) during operation on a dry, level road under reference conditions of 20 °C, 98.21 kPa, no wind, no precipitation, and the transmission in neutral. You may use other methods that are equivalent to SAE J2263, such as equivalent test procedures or analytical modeling, to characterize road load using good engineering judgment. Determine dynamometer settings to simulate the road-load profile represented by these road-load target coefficients as described in § 1066.315. Supply representative road-load forces for each vehicle at speeds above 15 km/hr (9.3 mi/hr), and up to 115 km/hr (71.5 mi/hr), or the highest speed from the range of applicable duty cycles. (b) For cold temperature testing described in subpart H of this part, determine road-load target coefficients using one of the following methods: (1) You may perform coastdown tests or use other methods to characterize road load as described in paragraph (a) of this section based on vehicle operation at a nominal ambient temperature of −7 °C (20 °F). (2) You may multiply each of the road-load target coefficients determined using the procedures described in paragraph (a) of this section by 1.1 to approximate a 10 percent decrease in coastdown time for the test vehicle. [80 FR 9121, Feb. 19, 2015, as amended at 81 FR 74202, Oct. 25, 2016; 89 FR 28211, Apr. 18, 2024] § 1066.310 Coastdown procedures for vehicles above 14,000 pounds GVWR. This section describes coastdown procedures that are unique to vehicles above 14,000 pounds GVWR. These procedures are valid for calculating road-load coefficients for chassis and post-transmission powerpack testing. These procedures are also valid for calculating drag area ( C d A (a) Determine road-load coefficients by performing a minimum of 16 valid coastdown runs (8 in each direction). (b) Follow the provisions of Sections 1 through 9 of SAE J1263 and SAE J2263 (incorporated by reference, see § 1066.1010), except as described in this paragraph (b). The terms and variables identified in this paragraph (b) have the meaning given in SAE J1263 or J2263 unless specified otherwise. (1) The test condition specifications of SAE J1263 apply except as follows for wind and road conditions: (i) We recommend that you do not perform coastdown testing on days for which winds are forecast to exceed 6.0 mi/hr. (ii) The grade of the test track or road must not be excessive (considering factors such as road safety standards and effects on the coastdown results). Road conditions should follow Section 7.4 of SAE J1263, except that road grade may exceed 0.5%. If road grade is greater than 0.02% over the length of the test surface, you must incorporate into the analysis road grade as a function of distance along the length of the test surface. Use Section 11.5 of SAE J2263 to calculate the force due to grade. (2) Operate the vehicle at a top speed above 70 mi/hr, or at its maximum achievable speed if it cannot reach 70 mi/hr. If a vehicle is equipped with a vehicle speed limiter that is set for a maximum speed below 70 mi/hr, you must disable the vehicle speed limiter. Start the test at or above 70 mi/hr, or at the vehicle's maximum achievable speed if it cannot reach 70 mi/hr. Collect data through a minimum speed at or below 15 mi/hr. Data analysis for valid coastdown runs must include the range of vehicle speeds specified in this paragraph (b)(2). (3) Gather data regarding wind speed and direction, in coordination with time-of-day data, using at least one stationary electro-mechanical anemometer and suitable data loggers meeting the specifications of SAE J1263, as well as the following additional specifications for the anemometer placed adjacent to the test surface: (i) Calibrate the equipment by running the zero-wind and zero-angle calibrations within 24 hours before conducting the coastdown procedures. If the coastdown procedures are not complete 24 hours after calibrating the equipment, repeat the calibration for another 24 hours of data collection. (ii) Record the location of the anemometer using a GPS measurement device adjacent to the test surface (approximately) at the midway distance along the test surface used for coastdowns. (iii) Position the anemometer such that it will be at least 2.5 but not more than 3.0 vehicle widths from the test vehicle's centerline as the test vehicle passes the anemometer. (iv) Mount the anemometer at a height that is within 6 inches of half the test vehicle's maximum height. (v) Place the anemometer at least 50 feet from the nearest tree and at least 25 feet from the nearest bush (or equivalent roadside features). (vi) The height of the grass surrounding the stationary anemometer may not exceed 10% of the anemometer's mounted height, within a radius equal to the anemometer's mounted height. (4) You may split runs as per Section 9.3.1 of SAE J2263, but we recommend whole runs. If you split a run, analyze each portion separately, but count the split runs as one run with respect to the minimum number of runs required. (5) You may perform consecutive runs in a single direction, followed by consecutive runs in the opposite direction, consistent with good engineering judgment. Harmonize starting and stopping points to the extent practicable to allow runs to be paired. (6) All valid coastdown run times in each direction must be within 2.0 standard deviations of the mean of the valid coastdown run times (from the specified maximum speed down to 15 mi/hr) in that direction. Eliminate runs outside this range. After eliminating these runs you must have at least eight valid runs in each direction. You may use coastdown run times that do not meet these standard deviation requirements if we approve it in advance. In your request, describe why the vehicle is not able to meet the specified standard deviation requirements and propose an alternative set of requirements. (7) Analyze data for chassis and post-transmission powerpack testing or for use in the GEM simulation tool as follows: (i) Follow the procedures specified in Section 10 of SAE J1263 or Section 11 of SAE J2263 to calculate coefficients for chassis and post-transmission powerpack testing. (ii) Determine drag area, C d A, (A) Measure vehicle speed at fixed intervals over the coastdown run (generally at 10 Hz), including speeds at or above 15 mi/hr and at or below the specified maximum speed. Establish the elevation corresponding to each interval as described in SAE J2263 if you need to incorporate the effects of road grade. (B) Calculate the vehicle's effective mass, M e, M, (C) Calculate the road-load force for each measurement interval, F i Where: i i i M e v Δ t (D) Plot the data from all the coastdown runs on a single plot of F i v i 2 D, Where: M a g Δh Δh Δs A m (E) Calculate drag area, C d A, 2 Where: r 3 T P (8) Determine the A, B, and C coefficients identified in § 1066.210 as follows: (i) For chassis and post-transmission powerpack testing, follow the procedures specified in Section 10 of SAE J1263 or Section 12 of SAE J2263. (ii) For the GEM simulation tool, use the following values: A = A m B = 0 C = D adj [79 FR 23823, Apr. 28, 2016, as amended at 81 FR 74202, Oct. 25, 2016; 89 FR 28211, Apr. 18, 2024] § 1066.315 Dynamometer road-load setting. Determine dynamometer road-load settings for chassis testing by following SAE J2264 (incorporated by reference, see § 1066.1010). [89 FR 28212, Apr. 18, 2024] Subpart E—Preparing Vehicles and Running an Exhaust Emission Test § 1066.401 Overview. (a) Use the procedures detailed in this subpart to measure vehicle emissions over a specified drive schedule. Different procedures may apply for criteria pollutants and greenhouse gas emissions as described in the standard-setting part. This subpart describes how to— (1) Determine road-load power, test weight, and inertia class. (2) Prepare the vehicle, equipment, and measurement instruments for an emission test. (3) Perform pre-test procedures to verify proper operation of certain equipment and analyzers and to prepare them for testing. (4) Record pre-test data. (5) Sample emissions. (6) Record post-test data. (7) Perform post-test procedures to verify proper operation of certain equipment and analyzers. (8) Weigh PM samples. (b) The overall test generally consists of prescribed sequences of fueling, parking, and driving at specified test conditions. An exhaust emission test generally consists of measuring emissions and other parameters while a vehicle follows the drive schedules specified in the standard-setting part. There are two general types of test cycles: (1) Transient cycles. (i) A cold-start transient cycle where you start to measure emissions just before starting an engine that has not been warmed up. (ii) A hot-start transient cycle where you start to measure emissions just before starting a warmed-up engine. (iii) A hot-running transient cycle where you start to measure emissions after an engine is started, warmed up, and running. (2) Cruise cycles. (i) Start a cruise cycle as a hot-running test, where you start to measure emissions after the engine is started and warmed up and the vehicle is running at the target test speed. (ii) Sample emissions and other parameters for the cruise cycle in the same manner as a transient cycle, with the exception that the reference speed value is constant. Record instantaneous and mean speed values over the cycle. § 1066.405 Vehicle preparation, preconditioning, and maintenance. (a) Prepare the vehicle for testing (including measurement of evaporative and refueling emissions if appropriate), as described in the standard-setting part. (b) If you inspect a vehicle, keep a record of the inspection and update your application for certification to document any changes that result. You may use any kind of equipment, instrument, or tool that is available at dealerships and other service outlets to identify malfunctioning components or perform maintenance. (c) You may repair defective parts from a test vehicle if they are unrelated to emission control. You must ask us to approve repairs that might affect the vehicle's emission controls. If we determine that a part failure, system malfunction, or associated repair makes the vehicle's emission controls unrepresentative of production engines, you may not use it as an emission-data vehicle. Also, if the engine installed in the test vehicle has a major mechanical failure that requires you to take the vehicle apart, you may no longer use the vehicle as an emission-data vehicle for exhaust measurements. [86 FR 34582, June 29, 2021] § 1066.410 Dynamometer test procedure. (a) Dynamometer testing may consist of multiple drive cycles with both cold-start and hot-start portions, including prescribed soak times before each test interval. The standard-setting part identifies the driving schedules and the associated sample intervals, soak periods, engine startup and shutdown procedures, and operation of accessories, as applicable. Not every test interval includes all these elements. (b) Place the vehicle onto the dynamometer without starting the engine (for any test cycles) or drive the vehicle onto the dynamometer (for hot-start and hot-running cycles only) and position a fan that directs cooling air to the vehicle during dynamometer operation as described in this paragraph (b). This generally requires squarely positioning the fan in front of the vehicle and directing the airflow to the vehicle's radiator. Use good engineering judgment to design and configure fans to cool the test vehicle in a way that properly simulates in-use operation, consistent with the specifications of § 1066.105. Except for the following special cases, use a road-speed modulated fan meeting the requirements of § 1066.105(c)(2) that is placed within 90 cm of the front of the vehicle and ensure that the engine compartment cover ( i.e., (1) For vehicles above 14,000 pounds GVWR, use a fan meeting the requirements of § 1066.105(d) that is placed within 90 cm of the front of the vehicle and ensure that the engine compartment cover is closed. (2) For FTP, LA-92, US06, or HFET testing of vehicles at or below 14,000 pounds GVWR, you may use a fixed-speed fan as specified in the following table, with the engine compartment cover open: Table 1 of § 1066.410—Fixed-Speed Fan Capacity and Position Specifications for Vehicles at or Below 14,000 pounds GVWR Test cycle Maximum fan Approximate distance from the front of the vehicle FTP Up to 2.50 m 3 0 to 30 cm. US06 Up to 7.10 m 3 0 to 60 cm. LA-92 Up to 7.10 m 3 0 to 60 cm. HFET Up to 2.50 m 3 0 to 30 cm. (3) For SC03 and AC17 testing, use a road-speed modulated fan meeting the requirements of § 1066.105(c)(5) that is placed within 60 to 90 cm of the front of the vehicle and ensure that the engine compartment cover is closed. Position the discharge nozzle such that its lowest point is not more than 16 cm above the floor of the test cell. (c) Record the vehicle's speed trace based on the time and speed data from the dynamometer at the recording frequencies given in Table 1 of § 1066.125. Record speed to at least the nearest 0.01 mi/hr and time to at least the nearest 0.1 s. (d) You may perform practice runs for operating the vehicle and the dynamometer controls to meet the driving tolerances specified in § 1066.425 or adjust the emission sampling equipment. Verify that the accelerator pedal allows for enough control to closely follow the prescribed driving schedule. We recommend that you verify your ability to meet the minimum dilution factor requirements of § 1066.110(b)(2)(iii)(B) during these practice runs. (e) Inflate tires on drive wheels according to the vehicle manufacturer's specifications. The tire pressure for drive wheels must be the same for dynamometer operation and for dynamometer coastdown procedures used for determining road-load coefficients. Report these measured tire pressure values with the test results. (f) Tie down or load the test vehicle as needed to provide a normal force at the tire and dynamometer roll interface to prevent wheel slip. For vehicles above 14,000 pounds GVWR, report this measured force with the test results. (g) Use good engineering judgment when testing vehicles in four-wheel drive or all-wheel drive mode. (For purposes of this paragraph (g), the term four-wheel drive includes other multiple drive-axle configurations.) This may involve testing on a dynamometer with a separate dynamometer roll for each drive axle; or two drive axles may use a single roll, as described in § 1066.210(d)(1); or you may deactivate the second set of drive wheels and operate the vehicle on a single roll. For all vehicles at or below 14,000 GVWR, we will test your vehicle using the same dynamometer roll arrangement that you used. We may also test your vehicle using another dynamometer roll arrangement for information-gathering purposes. If we choose to perform additional testing that requires vehicle modifications, we will ask you to configure the vehicle appropriately. (h) Determine equivalent test weight as follows: (1) For vehicles at or below 14,000 pounds GVWR, determine ETW as described in § 1066.805. Set dynamometer vehicle inertia, I (i) For two-wheel drive dynamometers, set I (ii) For four-wheel drive dynamometers, set I (2) For vehicles above 14,000 pounds GVWR, determine the vehicle's effective mass as described in § 1066.310 and use this as the test weight. (i) Warm up the dynamometer as recommended by the dynamometer manufacturer. (j) Following the test, determine the actual driving distance by counting the number of dynamometer roll or shaft revolutions, or by integrating speed over the course of testing from a high-resolution encoder system. [79 FR 23823, Apr. 28, 2014, as amended at 80 FR 9121, Feb. 19, 2015; 81 FR 74202, Oct. 25, 2016] § 1066.415 Vehicle operation. This section describes how to test a conventionally configured vehicle (vehicles with transmission shifters, foot pedal accelerators, etc). You may ask us to modify these procedures for vehicles that do not have these control features. (a) Start the vehicle as follows: (1) At the beginning of the test cycle, start the vehicle according to the procedure described in the owners manual. In the case of HEVs, this would generally involve activating vehicle systems such that the engine will start when the vehicle's control algorithms determine that the engine should provide power instead of or in addition to power from the rechargeable energy storage system (RESS). Unless we specify otherwise, engine starting throughout this part generally refers to this step of activating the system on HEVs, whether or not that causes the engine to start running. (2) Place the transmission in gear as described by the test cycle in the standard-setting part. During idle operation, apply the brakes if necessary to keep the drive wheels from turning. (b) If the vehicle does not start after your recommended maximum cranking time, wait and restart cranking according to your recommended practice. If you do not recommend such a cranking procedure, stop cranking after 10 seconds, wait for 10 seconds, then start cranking again for up to 10 seconds. You may repeat this for up to three start attempts. If the vehicle does not start after three attempts, you must determine and record the reason for failure to start. Shut off sampling systems and either turn the CVS off or disconnect the laboratory exhaust tubing from the tailpipe during the diagnostic period to prevent flow through the exhaust system. Reschedule the vehicle for testing. This may require performing vehicle preparation and preconditioning if the testing needs to be rerun from a cold start. If failure to start occurs during a hot-start test, you may reschedule the hot-start test without repeating the cold-start test, as long as you bring the vehicle to a hot-start condition before starting the hot-start test. (c) Repeat the recommended starting procedure if the engine has a false start (i.e., an incomplete start). (d) Take the following steps if the engine stalls: (1) If the engine stalls during an idle period, restart the engine immediately and continue the test. If you cannot restart the engine soon enough to allow the vehicle to follow the next acceleration, stop the driving schedule indicator and reactivate it when the vehicle restarts. (2) Void the test if the vehicle stalls during vehicle operation. If this happens, remove the vehicle from the dynamometer, take corrective action, and reschedule the vehicle for testing. Record the reason for the malfunction (if determined) and any corrective action. See the standard-setting part for instructions about reporting these malfunctions. (e) Operate vehicles during testing as follows: (1) Where we do not give specific instructions, operate the vehicle according to the recommendations in the owners manual, unless those recommendations are unrepresentative of what may reasonably be expected for in-use operation. (2) If vehicles have features that preclude dynamometer testing, you may modify these features as necessary to allow testing, consistent with good engineering judgment, as long as it does not affect your ability to demonstrate that your vehicles comply with the applicable standards in this chapter. Send us written notification describing these changes along with supporting rationale. (3) Operate vehicles during idle as follows: (i) For vehicles with automatic transmission, operate at idle with the transmission in “Drive” with the wheels braked, except that you may shift to “Neutral” for the first idle period and for any idle period longer than one minute. If you put the vehicle in “Neutral” during an idle, you must shift the vehicle into “Drive” with the wheels braked at least 5 seconds before the end of the idle period. Note that this does not preclude vehicle designs involving engine shutdown during idle. (ii) For vehicles with manual transmission, operate at idle with the transmission in gear with the clutch disengaged, except that you may shift to “Neutral” with the clutch engaged for the first idle period and for any idle period longer than one minute. If you put the vehicle in “Neutral” during idle, you must shift to first gear with the clutch disengaged at least 5 seconds before the end of the idle period. Note that this does not preclude vehicle designs involving engine operation with shutdown during idle. (4) Operate the vehicle with the appropriate accelerator pedal movement necessary to follow the scheduled speeds in the driving schedule. Avoid smoothing speed variations and unnecessary movement of the accelerator pedal. (5) Operate the vehicle smoothly, following representative shift speeds and procedures. For manual transmissions, the operator shall release the accelerator pedal during each shift and accomplish the shift without delay. If the vehicle cannot accelerate at the specified rate, operate it at maximum available power until the vehicle speed reaches the value prescribed in the driving schedule. (6) Decelerate as follows: (i) For vehicles with automatic transmission, use the brakes or accelerator pedal as necessary, without manually changing gears, to maintain the desired speed. (ii) For vehicles with manual transmission, shift gears in a way that represents reasonable shift patterns for in-use operation, considering vehicle speed, engine speed, and any other relevant variables. Disengage the clutch when the speed drops below 15 mi/hr, when engine roughness is evident, or when good engineering judgment indicates the engine is likely to stall. Manufacturers may recommend shift guidance in the owners manual that differs from the shift schedule used during testing, as long as both shift schedules are described in the application for certification; in this case, we may shift during testing as described in the owners manual. [79 FR 23823, Apr. 28, 2016, as amended at 81 FR 74202, Oct. 25, 2016; 88 FR 4708, Jan. 24, 2023] § 1066.420 Test preparation. (a) Follow the procedures for PM sample preconditioning and tare weighing as described in 40 CFR 1065.590 if you need to measure PM emissions. (b) Minimize the effect of nonmethane hydrocarbon contamination in the hydrocarbon sampling system for vehicles with compression-ignition engines as follows: (1) For vehicles at or below 14,000 pounds GVWR, account for contamination using one of the following methods: (i) Introduce zero and span gas during analyzer calibration using one of the following methods, noting that the hydrocarbon analyzer flow rate and pressure during zero and span calibration (and background bag reading) must be exactly the same as that used during testing to minimize measurement errors: (A) Close off the hydrocarbon sampling system sample probe and introduce gases downstream of the probe making sure that you do not pressurize the system. (B) Introduce zero and span gas directly at the hydrocarbon sampling system probe at a flow rate greater than 125% of the hydrocarbon analyzer flow rate allowing some gas to exit probe inlet. (ii) Perform the contamination verification in paragraph (b)(2) of this section, except use 0.5 µmol/mol in 40 CFR 1065.520(f)(8)(iii). (2) For vehicles above 14,000 pounds GVWR, verify the amount of nonmethane hydrocarbon contamination as described in 40 CFR 1065.520(f). (c) Unless the standard-setting part specifies different tolerances, verify at some point before the test that ambient conditions are within the tolerances specified in this paragraph (c). For purposes of this paragraph (c), “before the test” means any time from a point just prior to engine starting (excluding engine restarts) to the point at which emission sampling begins. (1) Ambient temperature must be (20 to 30) °C. See § 1066.425(h) for circumstances under which ambient temperatures must remain within this range during the test. (2) Dilution air conditions must meet the specifications in § 1066.110(b)(2). We recommend verifying dilution air conditions just before starting each test interval. (d) Control test cell ambient air humidity as follows: (1) For vehicles at or below 14,000 pounds GVWR, follow the humidity requirements in Table 1 of this section, unless the standard-setting part specifies otherwise. When complying with humidity requirements in Table 1, where no tolerance is specified, use good engineering judgment to maintain the humidity level near the specified value within the limitations of your test facility. (2) For vehicles above 14,000 pounds GVWR, you may test vehicles at any humidity. (3) Table 1 follows: Table 1 of § 1066.420—Test Cell Humidity Requirements Test cycle Humidity 2 Tolerance 2 AC17 69 ±5 average, ±10 instantaneous. FTP a 50 HFET 50 SC03 100 ±5 average. US06 50 a (e) You may perform a final calibration of proportional-flow control systems, which may include performing practice runs. (f) You may perform the following procedure to precondition sampling systems: (1) Operate the vehicle over the test cycle. (2) Operate any dilution systems at their expected flow rates. Prevent aqueous condensation in the dilution systems as described in 40 CFR 1065.140(c)(6), taking into account allowances given in § 1066.110(b)(2)(iv). (3) Operate any PM sampling systems at their expected flow rates. (4) Sample PM using any sample media. You may change sample media during preconditioning. You must discard preconditioning samples without weighing them. (5) You may purge any gaseous sampling systems during preconditioning. (6) You may conduct calibrations or verifications on any idle equipment or analyzers during preconditioning. (g) Take the following steps before emission sampling begins: (1) For batch sampling, connect clean storage media, such as evacuated bags or tare-weighed filters. (2) Start all measurement instruments according to the instrument manufacturer's instructions and using good engineering judgment. (3) Start dilution systems, sample pumps, and the data-collection system. (4) Pre-heat or pre-cool heat exchangers in the sampling system to within their operating temperature tolerances for a test. (5) Allow heated or cooled components such as sample lines, filters, chillers, and pumps to stabilize at their operating temperatures. (6) Adjust the sample flow rates to desired levels using bypass flow, if desired. (7) Zero or re-zero any electronic integrating devices before the start of any test interval. (8) Select gas analyzer ranges. You may not switch the gain of an analyzer's analog operational amplifier(s) during a test. However, you may switch (automatically or manually) gas analyzer ranges during a test if such switching changes only the range over which the digital resolution of the instrument is applied. For batch analyzers, select ranges before final bag analysis. (9) Zero and span all continuous gas analyzers using gases that meet the specifications of 40 CFR 1065.750. For FID analyzers, you may account for the carbon number of your span gas either during the calibration process or when calculating your final emission value. For example, if you use a C 3 8 RF PF (10) We recommend that you verify gas analyzer responses after zeroing and spanning by sampling a calibration gas that has a concentration near one-half of the span gas concentration. Based on the results, use good engineering judgment to decide whether or not to re-zero, re-span, or re-calibrate a gas analyzer before starting a test. (11) If you correct for dilution air background concentrations of associated engine exhaust constituents, start sampling and recording background concentrations at the same time you start sampling exhaust gases. (12) Turn on cooling fans immediately before starting the test. (h) Proceed with the test sequence described in § 1066.425. [79 FR 23823, Apr. 28, 2014, as amended at 80 FR 9121, Feb. 19, 2015; 86 FR 34582, June 29, 2021; 88 FR 4708, Jan. 24, 2023] § 1066.425 Performing emission tests. (a) See the standard-setting part for drive schedules. These are defined by a smooth fit of a specified speed vs. time sequence. (b) The driver must attempt to follow the target schedule as closely as possible, consistent with the specifications in paragraph (b) of this section. Instantaneous speeds must stay within the following tolerances: (1) The upper limit is 2.0 mi/hr higher than the highest point on the trace within 1.0 s of the given point in time. (2) The lower limit is 2.0 mi/hr lower than the lowest point on the trace within 1.0 s of the given time. (3) The same limits apply for vehicle operation without exhaust measurements, such as vehicle preconditioning and warm-up, except that the upper and lower limits for speed values are ±4.0 mi/hr. In addition, up to three occurrences of speed variations greater than the tolerance are acceptable for vehicle operation in which no exhaust emission standards apply, as long as they occur for less than 15 seconds on any occasion and are clearly documented as to the time and speed at that point of the driving schedule. (4) Void the test if you do not maintain speed values as specified in this paragraph (b), except as allowed by this paragraph (b)(4). Speed variations (such as may occur during gear changes or braking spikes) may occur as follows, as long as such variations are clearly documented, including the time and speed values and the reason for the deviation: (i) Speed variations greater than the specified limits are acceptable for up to 2.0 seconds on any occasion. (ii) For vehicles that are not able to maintain acceleration as specified in § 1066.415(e)(5), do not count the insufficient acceleration as being outside the specified limits. (5) We may approve an alternate test cycle and cycle-validation criteria for vehicles that do not have enough power to follow the specified driving trace. The alternate driving specifications must be based on making best efforts to maintain acceleration and speed to follow the specified test cycle. We must approve these alternate driving specifications before you perform this testing. (c) Figure 1 and Figure 2 of this section show the range of acceptable speed tolerances for typical points during testing. Figure 1 of this section is typical of portions of the speed curve that are increasing or decreasing throughout the 2-second time interval. Figure 2 of this section is typical of portions of the speed curve that include a maximum or minimum value. (d) Start testing as follows: (1) If a vehicle is already running and warmed up, and starting is not part of the test cycle, operate the vehicle as follows: (i) For transient test cycles, control vehicle speeds to follow a drive schedule consisting of a series of idles, accelerations, cruises, and decelerations. (ii) For cruise test cycles, control the vehicle operation to match the speed of the first interval of the test cycle. Follow the instructions in the standard-setting part to determine how long to stabilize the vehicle during each interval, how long to sample emissions at each interval, and how to transition between intervals. (2) If engine starting is part of the test cycle, start recording continuous data, turn on any electronic integrating devices, and start batch sampling before starting the engine. Initiate the driver's trace when the engine starts. (e) Perform the following at the end of each test interval, except as specified in standard-setting part: (1) Shut down the vehicle if it is part of the test cycle or if testing is complete. (2) Continue to operate all sampling and dilution systems to allow the response times to elapse. Then stop all sampling and recording, including background sampling. Finally, stop any integrating devices and indicate the end of the duty cycle in the recorded data. (f) If testing involves engine shutdown followed by another test interval, start a timer for the vehicle soak when the engine shuts down. Turn off cooling fans, close the engine compartment cover (if applicable), and turn off the CVS or disconnect the exhaust tube from the vehicle's tailpipe(s) unless otherwise instructed in the standard-setting part. If testing is complete, disconnect the laboratory exhaust tubing from the vehicle's tailpipe(s) and drive the vehicle from the dynamometer. (g) Take the following steps after emission sampling is complete: (1) For any proportional batch sample, such as a bag sample or PM sample, verify that proportional sampling was maintained according to 40 CFR 1065.545. Void any samples that did not maintain proportional sampling according to those specifications. (2) Place any used PM samples into covered or sealed containers and return them to the PM-stabilization environment. Follow the PM sample post-conditioning and total weighing procedures in 40 CFR 1065.595. (3) As soon as practical after the interval or test cycle is complete, or optionally during the soak period if practical, perform the following: (i) Begin drift check for all continuous gas analyzers as described in paragraph (g)(5) of this section and zero and span all batch gas analyzers as soon as practical before any batch sample analysis. You may perform this batch analyzer zero and span before the end of the test interval. (ii) Analyze any conventional gaseous batch samples (HC, CH 4 X 2 (iii) Analyze nonconventional gaseous batch samples (including background), such as NMHCE, N 2 (4) If an analyzer operated above 100% of its range at any time during the test, perform the following steps: (i) For batch sampling, re-analyze the sample using the lowest analyzer range that results in a maximum instrument response below 100%. Report the result from the lowest range from which the analyzer operates below 100% of its range. (ii) For continuous sampling, repeat the entire test using the next higher analyzer range. If the analyzer again operates above 100% of its range, repeat the test using the next higher range. Continue to repeat the test until the analyzer consistently operates at less than 100% of its range. Keep records of any tests where the analyzer exceeds its range. We may consider these results to determine that the test vehicle exceeded an emission standard, consistent with good engineering judgment. (5) After quantifying exhaust gases, verify drift as follows: (i) For batch and continuous gas analyzers, record the mean analyzer value after stabilizing a zero gas to the analyzer. Stabilization may include time to purge the analyzer of any sample gas, plus any additional time to account for analyzer response. (ii) Record the mean analyzer value after stabilizing the span gas to the analyzer. Stabilization may include time to purge the analyzer of any sample gas, plus any additional time to account for analyzer response. (iii) Use these data to verify that analyzer drift does not exceed 2.0% of the analyzer full scale. (h) Measure and record ambient pressure. Measure and record ambient temperature continuously to verify that it remains within the temperature range specified in § 1066.420(c)(1) throughout the test. Also measure humidity if required, such as for correcting NO X (i) [Reserved] (j) For vehicles at or below 14,000 pounds GVWR, determine overall driver accuracy as follows: (1) Compare the following drive-cycle metrics, based on measured vehicle speeds, to a reference value based on the target cycle that would have been generated by driving exactly to the target trace as described in SAE J2951 (incorporated by reference, see § 1066.1010): (i) Determine the Energy Economy Rating as described in Section 5.4 of SAE J2951. (ii) Determine the Absolute Speed Change Rating as described in Section 5.5 of SAE J2951. (iii) Determine the Inertia Work Rating as described in Section 5.6 of SAE J2951. (iv) Determine the phase-weighted composite Energy Based Drive Metrics for the criteria specified in this paragraph (j)(1) as described in Section 5.7 of SAE J2951. (2) The standard-setting part may require you to give us 10 Hz data to characterize both target and actual values for cycle energy. Calculate target values based on the vehicles speeds from the specified test cycle. [79 FR 23823, Apr. 28, 2016, as amended at 81 FR 74203, Oct. 25, 2016; 89 FR 28212, Apr. 18, 2024] Subpart F—Electric Vehicles and Hybrid Electric Vehicles § 1066.501 Overview. Use the following procedures to test EVs and HEVs (including PHEVs): (a) Correct the results for Net Energy Change of the RESS as follows: (1) For all sizes of EV, follow SAE J1634 (incorporated by reference, see § 1066.1010). (2) For HEV at or below 14,000 pounds GVWR, follow SAE J1711 (incorporated by reference, see § 1066.1010) except as described in this paragraph (a). Disregard provisions of SAE J1711 that differ from this part or the standard-setting part if they are not specific to HEV. Apply the following adjustments and clarifications to SAE J1711: (i) If the procedure calls for charge-sustaining operation, start the drive with a State of Charge that is appropriate to ensure charge-sustaining operation for the duration of the drive. Take steps other than emission measurements to confirm that vehicles are in charge-sustaining mode for the duration of the drive. (ii) You may use Appendix C of SAE J1711 for charge-sustaining tests to correct final fuel economy values, CO 2 (iii) You may test subject to a measurement accuracy of ±0.3% of full scale in place of the measurement accuracy specified in Section 4.4 of SAE J1711. (3) For HEV above 14,000 pounds GVWR, follow SAE J2711 (incorporated by reference, see § 1066.1010) for requirements related to charge-sustaining operation. (b) This paragraph (b) applies for vehicles that include an engine-powered generator or other auxiliary power unit that provides motive power. For example, this would include a vehicle that has a small gasoline engine that generates electricity to charge batteries. Unless we approve otherwise, measure emissions for all test cycles when such an engine is operating. For each test cycle for which emissions are not measured, you must validate that such engines are not operating at any time during the test cycle. (c) You may stop emission sampling anytime the engine is turned off, consistent with good engineering judgment. This is intended to allow for higher concentrations of dilute exhaust gases and more accurate measurements. Take steps to account for exhaust transport delay in the sampling system, and be sure to integrate over the actual sampling duration when determining V mix [79 FR 23823, Apr. 28, 2014, as amended at 80 FR 9121, Feb. 19, 2015; 89 FR 28212, Apr. 18, 2024] Subpart G—Calculations § 1066.601 Overview. (a) This subpart describes calculations used to determine emission rates. See the standard-setting part and the other provisions of this part to determine which equations apply for your testing. This subpart describes how to— (1) Use the signals recorded before, during, and after an emission test to calculate distance-specific emissions of each regulated pollutant. (2) Perform calculations for calibrations and performance checks. (3) Determine statistical values. (b) You may use data from multiple systems to calculate test results for a single emission test, consistent with good engineering judgment. You may also make multiple measurements from a single batch sample, such as multiple weighing of a PM filter or multiple readings from a bag sample. Although you may use an average of multiple measurements from a single test, you may not use test results from multiple emission tests to report emissions. We allow weighted means where appropriate, such as for sampling onto a PM filter over the FTP. You may discard statistical outliers, but you must report all results. § 1066.605 Mass-based and molar-based exhaust emission calculations. (a) Calculate your total mass of emissions over a test cycle as specified in paragraph (c) of this section or in 40 CFR part 1065, subpart G, as applicable. (b) See the standard-setting part for composite emission calculations over multiple test intervals and the corresponding weighting factors. (c) Perform the following sequence of preliminary calculations to correct recorded concentration measurements before calculating mass emissions in paragraphs (e) and (f) of this section: (1) For vehicles above 14,000 pounds GVWR, correct all THC and CH 4 (2) Correct all concentrations measured on a “dry” basis to a “wet” basis, including dilution air background concentrations. (3) Calculate all NMHC and CH 4 (4) For vehicles at or below 14,000 pounds GVWR, calculate HC concentrations, including dilution air background concentrations, as described in this section, and as described in § 1066.635 for NMOG. For emission testing of vehicles above 14,000 pounds GVWR, with fuels that contain 25% or more oxygenated compounds by volume, calculate THCE and NMHCE concentrations, including dilution air background concentrations, as described in 40 CFR part 1065, subpart I. (5) Correct all gaseous concentrations for dilution air background as described in § 1066.610. (6) Correct NO X (7) Correct all PM filter masses for sample media buoyancy as described in 40 CFR 1065.690. (d) Calculate g/mile emission rates using the following equation unless the standard-setting part specifies otherwise: Where: e [emission] m [emission] D Example: m NOx D HFET (e) Calculate the emission mass of each gaseous pollutant using the following equation: Where: m [emission] V mix p [emission] x [emission] c −2 −6 Example: V mix 3 r NOx 3 x NOx c −6 m NOx −6 (f) Calculation of the emission mass of PM, m PM, (1) Except as otherwise specified in this paragraph (f), calculate m PM Where: m PM V mix V mix V PMstd V sdastd V sdastd m PMfil m PMbkgnd Example: V mix 3 V PMstd 3 V sdastd 3 m PMfil m PMbkgnd (2) If you sample PM onto a single filter as described in § 1066.815(b)(4)(i) or (b)(4)(ii) (for constant volume samplers), calculate m PM Where: m PM V mix V [interval]-PMstd V [interval]-sdastd m PMfil m PMbkgnd Example: V mix 3 V ct-PMstd 3 V ct-sdastd 3 V s-PMstd 3 V s-sdastd 3 V ht-PMstd 3 V ht-sdastd 3 m PMfil m PMbkgnd m PM (3) If you sample PM onto a single filter as described in § 1066.815(b)(4)(ii) (for partial flow dilution systems), calculate m PM Where: m PM V [interval]-exhstd V [interval]-PMstd V [interval]-dilstd m PMfil m PMbkgnd Example: V ct-exhstd 3 V ct-PMstd 3 V ct-dilstd 3 V s-exhstd 3 V s-PMstd 3 V s-dilstd 3 V ht-exhstd 3 V ht-PMstd 3 V ht-dilstd 3 m PMfil m PMbkgnd m PM (4) If you sample PM onto a single filter as described in § 1066.815(b)(5)(i) or (b)(5)(ii) (for constant volume samplers), calculate m PM Where: m PM V mix V [interval]-PMstd V [interval]-sdastd m PMfil m PMbkgnd Example: V mix 3 V ct-PMstd 3 V ct-sdastd 3 V cs-PMstd 3 V cs-sdastd 3 V ht-PMstd 3 V ht-sdastd 3 V hs-PMstd 3 V hs-sdastd 3 m PMfil m PMbkgnd m PM (5) If you sample PM onto a single filter as described in § 1066.815(b)(5)(ii) (for partial flow dilution systems), calculate m PM Where: m PM V [interval]-exhstd V [interval]-PMstd V [interval]-dilstd m PMfil m PMbkgnd Example: V ct-exhstd 3 V ct-PMstd 3 V ct-dilstd 3 V cs-exhstd 3 V cs-PMstd 3 V cs-dilstd 3 V ht-exhstd 3 V ht-PMstd 3 V ht-dilstd 3 V hs-exhstd 3 V hs-PMstd 3 V hs-dilstd 3 m PMfil m PMbkgnd m PM (g) This paragraph (g) describes how to correct flow and flow rates to standard reference conditions and provides an example for determining V mix (1) Correct flow and flow rates to standard reference conditions as needed using the following equation: Where: V [flow]std V [flow]act p in T std p std T in Example: V PMact 3 p in T std p std T in (2) The following example provides a determination of V mix V mix V mix Where: V CVSstd V gasstd V PMstd V sdastd Example: Using Eq. 1066.605-8: V CVSstd 3 V CVSact 3 p in T in Using Eq. 1066.605-8: V gasstd 3 V gasact 3 p in T in Using Eq. 1066.605-8: V PMstd 3 V PMact 3 p in T in Using Eq. 1066.605-8: V sdastd 3 V sdaact 3 p in T in V mix 3 (h) Calculate total flow volume over a test interval, V [flow], (1) Varying versus constant flow rates. (i) We consider the following to be examples of varying flows that require a continuous multiplication of concentration times flow rate: raw exhaust, exhaust diluted with a constant flow rate of dilution air, and CVS dilution with a CVS flow meter that does not have an upstream heat exchanger or electronic flow control. (ii) We consider the following to be examples of constant exhaust flows: CVS diluted exhaust with a CVS flow meter that has an upstream heat exchanger, an electronic flow control, or both. (2) Continuous sampling. (i) Varying flow rate. V [flow] Where: Δ t record Eq. 1066.605-11 Example: N Q CVS1 3 Q CVS2 3 ƒ record Using Eq. 1066.605-11: Δ t V CVS Q CVS505 V CVS 3 (ii) Constant flow rate. (3) Batch sampling. (i) Varying flow rate. (ii) Constant flow rate. V [flow] Example: Q CVS 3 Δ t V CVS V CVS 3 [79 FR 23823, Apr. 28, 2014, as amended at 80 FR 9121, Feb. 19, 2015; 81 FR 74203, Oct. 25, 2016; 86 FR 34583, June 29, 2021] § 1066.610 Dilution air background correction. (a) Correct the emissions in a gaseous sample for background using the following equation: Where: x [emission]dexh x [emission]bkgnd DF Where: x CO2 2 x NMHC 1 x CH4 4 x CO a a b b (c) Determine the dilution factor, DF Where: V dexhstd V exhstd (d) Determine the time-weighted dilution factor, DF w Where: N i t DF Example: N DF 1 t 1 DF 2 t 2 DF 3 t 3 [79 FR 23823, Apr. 28, 2014, as amended at 86 FR 34583, June 29, 2021] § 1066.615 NO X You may correct NO X X (a) For vehicles at or below 14,000 pounds GVWR, apply a correction for vehicles with reciprocating engines operating over specific test cycles as follows: (1) Calculate a humidity correction using a time-weighted mean value for ambient humidity over the test interval. Calculate absolute ambient humidity, H Where: M H2O 2 p d RH M air p atmos Example: M H2O p d RH M air p atmos (2) Use the following equation to correct measured concentrations to a reference condition of 10.71 grams H 2 Where: χ NOx X H s H Example: H 2 χ NOx (b) For vehicles above 14,000 pounds GVWR, apply correction factors as described in 40 CFR 1065.670. [80 FR 9121, Feb. 19, 2015, as amended at 81 FR 74207, Oct. 25, 2016] § 1066.620 Removed water correction. Correct for removed water if water removal occurs upstream of a concentration measurement and downstream of a flow meter used to determine mass emissions over a test interval. Perform this correction based on the amount of water at the concentration measurement and on the amount of water at the flow meter. § 1066.625 Flow meter calibration calculations. This section describes the calculations for calibrating various flow meters based on mass flow rates. Calibrate your flow meter according to 40 CFR 1065.640 instead if you calculate emissions based on molar flow rates. (a) PDP calibration. (1) Calculate PDP volume pumped per revolution, V rev, Where: V ref T in p std f nPDP P in T std Example: V ref 3 T in p std f nPDP P in T std V rev 3 (2) Calculate a PDP slip correction factor, K s Where: f m PDP p out p in (3) Perform a least-squares regression of V rev K s a 1 a 0 (4) Repeat the procedure in paragraphs (a)(1) through (3) of this section for every speed that you run your PDP. (5) The following example illustrates a range of typical values for different PDP speeds: Table 1 of § 1066.625—Example of PDP Calibration Data f nPDP a 1 3 a 0 3 12.6 0.841 0.056 16.5 0.831 −0.013 20.9 0.809 0.028 23.4 0.788 −0.061 (6) For each speed at which you operate the PDP, use the appropriate regression equation from this paragraph (a) to calculate flow rate during emission testing as described in § 1066.630. (b) SSV calibration. Z C f g C p C v. γ (1) Calculate volume flow rate at standard reference conditions, V std Where: C d C f A t R p in T std p std Z M mix T in (2) Perform the following steps to calibrate an SSV flow meter: (i) Using the data collected in § 1066.140, calculate C d Where: V ref (ii) Use the following equation to calculate C f Where: g C p C v r b (iii) Calculate r Where: Δ p (iv) You may apply any of the following simplifying assumptions or develop other values as appropriate for your test configuration, consistent with good engineering judgment: (A) For raw exhaust, diluted exhaust, and dilution air, you may assume that the gas mixture behaves as an ideal gas ( Z (B) For raw exhaust, you may assume g (C) For diluted exhaust and dilution air, you may assume g (D) For diluted exhaust and dilution air, you may assume the molar mass of the mixture, M mix Where: M air x H2O 2 M H2O Example: M air x H2O M H2O M mix M mix (E) For diluted exhaust and dilution air, you may assume a constant molar mass of the mixture, M mix Table 2 of § 1066.625—Examples of Dilution Air and Calibration Air Dewpoints at Which You May Assume a Constant M mix If calibration T dew assume the following M mix for the following ranges of T dew a ≤0 28.96559 ≤18 0 28.89263 ≤21 5 28.86148 ≤22 10 28.81911 ≤24 15 28.76224 ≤26 20 28.68685 −8 to 28 25 28.58806 12 to 31 30 28.46005 23 to 34 a (v) The following example illustrates the use of the governing equations to calculate C d V ref 3 Z M mix R 2 2 T in A t 2 p in 2 g b Δp C f C d (vi) Calculate the Reynolds number, Re # V refstd d t r std m Re # m m Re # Where, using the Sutherland three-coefficient viscosity model: Where: m 0 T 0 S Table 3 of § 1066.625—Sutherland Three-Coefficient Viscosity Model Parameters Gas 1 m 0 T 0 S Temperature range within ±2% error 2 Pressure limit 2 kg/(m·s) K K K kPa Air 1.716·10 −5 273 111 170 to 1900 ≤1800. CO 2 1.370·10 −5 273 222 190 to 1700 ≤3600. H 2 1.12·10 −5 350 1064 360 to 1500 ≤10000. O 2 1.919·10 −5 273 139 190 to 2000 ≤2500. N 2 1.663·10 −5 273 107 100 to 1500 ≤1600. 1 2 Example: m 0 −5 T 0 S T in d t r std 3 Re # 6 (vii) Calculate r Example: ρ std 3 (viii) Create an equation for C d Re # C d Re # (ix) Perform a least-squares regression analysis to determine the best-fit coefficients for the equation and calculate SEE (x) If the equation meets the criterion of SEE C dmax Re # (xi) If the equation does not meet the specified statistical criteria, you may use good engineering judgment to omit calibration data points; however, you must use at least seven calibration data points to demonstrate that you meet the criterion. For example, this may involve narrowing the range of flow rates for a better curve fit. (xii) Take corrective action if the equation does not meet the specified statistical criterion even after omitting calibration data points. For example, select another mathematical expression for the C d Re # (xiii) Once you have an equation that meets the specified statistical criterion, you may use the equation only for the corresponding range of Re # (c) CFV calibration. K v K v (1) To determine K v (i) Calculate an individual K v Where: V refstd T in P in (ii) Calculate the mean and standard deviation of all the K v K v p in K v K v (iii) If the standard deviation of all the K v K v K v r Where: Δ p CFV p in (iv) If the standard deviation of all the K v K v K v r (v) If the number of remaining data points is less than seven, take corrective action by checking your calibration data or repeating the calibration process. If you repeat the calibration process, we recommend checking for leaks, applying tighter tolerances to measurements and allowing more time for flows to stabilize. (vi) If the number of remaining K v K v (vii) If the standard deviation of the remaining K v K v K v r K v (viii) If the standard deviation of the remaining K v K v (2) During exhaust emission tests, monitor sonic flow in the CFV by monitoring r. K v r r r r [79 FR 23823, Apr. 28, 2016, as amended at 81 FR 74208, Oct. 25, 2016] § 1066.630 PDP, SSV, and CFV flow rate calculations. This section describes the equations for calculating flow rates from various flow meters. After you calibrate a flow meter according to § 1066.625, use the calculations described in this section to calculate flow during an emission test. Calculate flow according to 40 CFR 1065.642 instead if you calculate emissions based on molar flow rates. (a) PDP. a 1, a 0, v Where: f nPDP V rev T std p in T in p std (2) Calculate V rev Eq. 1066.630-2 Where: p out Example: a 1 3 f nPDP p out p in a 0 3 T in (b) SSV. v Where: C d C d Re # C f A t R p in T std p std Z M mix T in Example: C d C f A t 2 R 2 2 p in T std p std Z M mix T in V 3 (c) CFV. K v, V V K v (1) To calculate V K v V Where: K v T in p in Example: K v 3 0.5 p in T in V 3 (2) [Reserved] [81 FR 74211, Oct. 25, 2016, as amended at 89 FR 28212, Apr. 18, 2024] § 1066.635 NMOG determination. For vehicles subject to an NMOG standard, determine NMOG as described in paragraph (a) of this section. Except as specified in the standard-setting part, you may alternatively calculate NMOG results based on measured NMHC emissions as described in paragraphs (c) through (f) of this section. Note that references to the FTP in this section apply for testing over the FTP test cycle at any ambient temperature. (a) Determine NMOG by independently measuring alcohols and carbonyls as described in 40 CFR 1065.805 and 1065.845. Use good engineering judgment to determine which alcohols and carbonyls you need to measure. This would typically require you to measure all alcohols and carbonyls that you expect to contribute 1% or more of total NMOG. Calculate the mass of NMOG in the exhaust, m NMOG, Where: m NMHC ρ NMHC. r NMHC 1 m OHCi i r OCHi 1 i. RF OHCi[THC-FID] i 1 (b) The following example shows how to determine NMOG as described in paragraph (a) of this section for (OHC) compounds including ethanol (C 2 5 3 2 4 2 1 m NMHC m CH3OH m C2H5OH m CH2O m C2H4O RF CH3OH[THC-FID] RF C2H5OH[THC-FID] RF CH2O[THC-FID] RF C2H4O[THC-FID] r NMHC-liq 3 r CH3OH 3 r C2H5OH 3 r CH2O 3 r C2H4O 3 (c) For gasoline containing less than 25% ethanol by volume, you may calculate NMOG from measured NMHC emissions as follows: (1) For hot-start and hot-running test cycles or intervals other than the FTP, you may determine NMOG based on the NMHC emission rate using the following equation: Where: e NMOGh e NMHCh r NMHC-liq Example: e NMHCh e NMOGh (2) You may determine weighted composite NMOG for FTP testing based on the weighted composite NMHC emission rate and the volume percent of ethanol in the fuel using the following equation: Where: e NMOGcomp e NMHCcomp r NMHC-liq VP EtOH Example: e NMHCcomp VP EtOH e NMOGcomp (3) You may determine NMOG for the transient portion of the FTP cold-start test for use in fuel economy and CREE calculations based on the NMHC emission rate for the test interval and the volume percent of ethanol in the fuel using the following equation: Where: e NMOG-FTPct e NMHC-FTPct r NMHC-liq Example: e NMHC-FTPct VP EtOH e NMOG-FTPct (4) You may determine NMOG for the stabilized portion of the FTP test for either the cold-start test or the hot-start test (bag 2 or bag 4) for use in fuel economy and CREE calculations based on the corresponding NMHC emission rate and the volume percent of ethanol in the fuel using the following equation: Where: e NMOG-FTPcs-hs e NMHC-FTPcs-hs r NMHC-liq (5) You may determine NMOG for the transient portion of the FTP hot-start test for use in fuel economy and CREE calculations based on the NMHC emission rate for the test interval and the volume percent of ethanol in the fuel using the following equation: Where: e NMOG-FTPht e NMHC-FTPht r NMHC-liq (6) For PHEVs, you may determine NMOG based on testing over one full UDDS using Eq. 1066.635-3. (d) You may take the following alternative steps when determining fuel economy and CREE under 40 CFR part 600 for testing with ethanol-gasoline blends that have up to 25% ethanol by volume: (1) Calculate NMOG by test interval using Eq. 1066.635-3 for individual bag measurements from the FTP. (2) For HEVs, calculate NMOG for two-bag FTPs using Eq. 1066.635-3 as described in 40 CFR 600.114. (e) We consider NMOG values for diesel-fueled vehicles, CNG-fueled vehicles, LNG-fueled vehicles, and LPG-fueled vehicles to be equivalent to NMHC emission values for all test cycles. (f) For all fuels not covered by paragraphs (c) and (e) of this section, manufacturers may propose a methodology to calculate NMOG results from measured NMHC emissions. We will approve adjustments based on comparative testing that demonstrates how to properly represent NMOG based on measured NMHC emissions. [79 FR 23823, Apr. 28, 2014, as amended at 80 FR 9122, Feb. 19, 2015; 81 FR 74212, Oct. 25, 2016; 89 FR 28212, Apr 18, 2024] § 1066.695 Data requirements. Record information for each test as follows: (a) Test number. (b) A brief description of the test vehicle (or other system/device tested). (c) Date and time of day for each part of the test sequence. (d) Test results. Also include a validation of driver accuracy as described in § 1066.425(j). (e) Driver and equipment operators. (f) Vehicle information as applicable, including identification number, model year, applicable emission standards (including bin standards or family emission limits, as applicable), vehicle model, vehicle class, test group, durability group, engine family, evaporative/refueling emission family, basic engine description (including displacement, number of cylinders, turbocharger/supercharger used, and catalyst type), fuel system (type of fuel injection and fuel tank capacity and location), engine code, GVWR, applicable test weight, inertia weight class, actual curb weight at zero miles, actual road load at 50 mi/hr, transmission class and configuration, axle ratio, odometer reading, idle rpm, and measured drive wheel tire pressure. (g) Dynamometer identification, inertia weight setting, indicated power absorption setting, and records to verify compliance with the driving distance and cycle-validation criteria as calculated from measured roll or shaft revolutions. (h) Analyzer bench identification, analyzer ranges, recordings of analyzer output during zero, span, and sample readings. (i) Associate the following information with the test record: test number, date, vehicle identification, vehicle and equipment operators, and identification of the measurements recorded. (j) Test cell barometric pressure and humidity. You may use a central laboratory barometer if the barometric pressure in each test cell is shown to be within ±0.1% of the barometric pressure at the central barometer location. (k) Records to verify compliance with the ambient temperature requirements throughout the test procedure and records of fuel temperatures during the running loss test. (l) [Reserved] (m) For CVS systems, record dilution factor for each test interval and the following additional information: (1) For CFV and SSV testing, V mix (2) For PDP testing, test measurements required to calculate V mix (n) The humidity of the dilution air, if you remove H 2 (o) Temperature of the dilute exhaust mixture and secondary dilution air (in the case of a double-dilution system) at the inlet to the respective gas meter or flow instrumentation used for PM sampling. Determine minimum values, maximum values, mean values, and percent of time outside of the tolerance over each test interval. (p) The maximum exhaust gas temperature over the course of the test interval within 20 cm upstream or downstream of PM sample media. (q) If applicable, the temperatures of the heated FID, the gas in the heated sample line, and the heated filter. Determine minimum values, maximum values, average values, and percent of time outside of the tolerance over each test interval. (r) Gas meter or flow measurement instrumentation readings used for batch sampling over each test interval. Determine minimum, maximum, and average values over each test interval. (s) The stabilized pre-test weight and post-test weight of each particulate sample media (e.g., filter). (t) Continuous temperature and humidity of the ambient air in which the PM sample media are stabilized. Determine minimum values, maximum values, average values, and percent of time outside of the tolerance over each test interval. (u) For vehicles fueled by natural gas, the test fuel composition, including all carbon-containing compounds (including CO 2 1 2 3 5 6 (v) For vehicles fueled by liquefied petroleum gas, the test fuel composition, including all carbon-containing compounds (including CO 2 1 4 5 (w) For the AC17 test in § 1066.845, interior volume, climate control system type and characteristics, refrigerant used, compressor type, and evaporator/condenser characteristics. (x) Additional information related to evaporative emissions. [Reserved] (y) Additional information related to refueling emissions. [Reserved] [[79 FR 23823, Apr. 28, 2016, as amended at 81 FR 74213, Oct. 25, 2016] Subpart H—Cold Temperature Test Procedures § 1066.701 Applicability and general provisions. (a) The procedures of this part 1066 may be used for testing at any ambient temperature. Section 1066.710 describes the provisions that apply for testing vehicles at a nominal temperature of −7 °C (20 °F); these procedures apply for motor vehicles as described in 40 CFR part 86, subpart S, and 40 CFR part 600. For other vehicles, see the standard-setting part to determine if your vehicle is required to meet emission standards outside the normal (20 to 30) °C ((68 to 86) °F) temperature range. (b) Do not apply the humidity correction factor in § 1066.615(a) for cold temperature testing. [79 FR 23823, Apr. 28, 2014, as amended at 80 FR 9122, Feb. 19, 2015] § 1066.710 Cold temperature testing procedures for measuring NMOG, NO X This section describes procedures for measuring emissions of nonmethane organic gas (NMOG), oxides of nitrogen (NO X X (a) Follow the exhaust emission measurement procedures specified in §§ 1066.410 through 1066.425 and § 1066.815(d), subject to the following exceptions and additional provisions: (1) Measure and control ambient conditions as specified in paragraph (b) of this section. (2) Use the vehicle's heater and defroster as specified in paragraph (c) of this section. (3) Precondition and stabilize the vehicle as specified in paragraphs (d) and (e) of this section. Ensure that there is no precipitation or dew on the vehicle before the emission test. (4) For dynamometers that have independently heated bearings, start the emission test within 20 minutes after warming up the dynamometer; for other types of dynamometers, start the emission test within 10 minutes after warming up the dynamometer. (5) Adjust the dynamometer to simulate vehicle operation on the road at −7 °C as described in § 1066.305(b). (6) Analyze samples for NMOG, NO X 2 (b) Maintain ambient conditions as follows instead of following the specifications in subpart E of this part: (1) Ambient temperature for emission tests. (2) Ambient temperature for preconditioning. X 2 (3) Ambient humidity. (c) During the test, operate the vehicle's interior climate control system with the heat on and air conditioning off. You may not use any supplemental auxiliary heat during this testing. You may set the heater to any temperature and fan setting during vehicle preconditioning. (1) Manual and automatic temperature control. (i) Set the climate control system as follows before the first acceleration (t = 20 s), or before starting the vehicle if the climate control system allows it: (A) Temperature. (B) Fan speed (C) Airflow direction (D) Air source. (ii) At the second idle of the test cycle, which occurs 125 seconds after the start of the test, set the fan speed to maximum. Complete by 130 seconds after the start of the test. Leave temperature and air source settings unchanged. (iii) At the sixth idle of the test interval, which occurs at the deceleration to zero miles per hour 505 seconds after the start of the test, set the fan speed to the lowest setting that maintains air flow. Complete these changes by 510 seconds after the start of the test. You may use different vent and fan speed settings for the remainder of the test. Leave the temperature and air source settings unchanged. (2) Full automatic control. (3) Multiple-zone systems. (4) A lternative test procedures. (d) Take the following steps to prepare and precondition vehicles for testing under this section: (1) Prepare the vehicle as described in § 1066.810(a). (2) Fill the fuel tank to approximately 40% of the manufacturer's nominal fuel tank capacity. Use the appropriate gasoline test fuel for low-temperature testing as specified 40 CFR 1065.710 or use ultra low-sulfur diesel fuel as specified in 40 CFR 1065.703. However, you may ask us to approve an alternative formulation of diesel fuel under 40 CFR 1065.10(c)(1) if that better represents in-use diesel fuel in winter conditions. The temperature of the dispensed test fuel must be at or below 15.5 °C. If the leftover fuel in the fuel tank before the refueling event does not meet these specifications, drain the fuel tank before refueling. You may operate the vehicle prior to the preconditioning drive to eliminate fuel effects on adaptive memory systems. (3) You may start the preconditioning drive once the fuel in the fuel tank reaches (−12.6 to −1.4) °C. Precondition the vehicle as follows: (i) Push or drive the vehicle onto the dynamometer. (ii) Operate the vehicle over one UDDS. You may perform additional vehicle preconditioning with repeated driving over the UDDS, subject to our advance approval. (iii) Turn off the test vehicle and any cooling fans within 5 minutes after completing the preconditioning drive. Ambient temperature must be between (−12.0 and −1.0) °C in the 5 minutes following the preconditioning drive. (iv) Do not manually purge or load the evaporative canister. (e) Soak the vehicle for (12 to 36) hours to stabilize it at test temperatures before starting the emission test as described in this paragraph (e). If you move a stabilized vehicle through a warm area when transporting it to the dynamometer for testing, you must restabilize the vehicle by holding it at an ambient temperature within the range specified in paragraph (b)(1) of this section for at least six times as long as the vehicle was exposed to warmer temperatures. Use one of the following methods to reach a stabilized condition: (1) Cold storage. (2) Forced-cooling or warming. (f) The following figure illustrates the cold temperature testing sequence for measuring CO and NMHC emissions and determining fuel economy: Figure 1 to paragraph (f) § 1066.710—Cold Temperature Testing Sequence for Measuring CO and NMHC Emissions and Determining Fuel Economy [79 FR 23823, Apr. 28, 2014, as amended at 80 FR 9122, Feb. 19, 2015; 81 FR 74213, Oct. 25, 2016; 86 FR 34583, June 29, 2021; 88 FR 4708, Jan. 24, 2023; 89 FR 28212, Apr. 18, 2024] Subpart I—Exhaust Emission Test Procedures for Motor Vehicles § 1066.801 Applicability and general provisions. This subpart I specifies how to apply the test procedures of this part for light-duty vehicles, light-duty trucks, and heavy-duty vehicles at or below 14,000 pounds GVWR that are subject to chassis testing for exhaust emissions under 40 CFR part 86, subpart S. For these vehicles, references in this part 1066 to the standard-setting part include subpart H of this part and this subpart I. (a) Use the procedures detailed in this subpart to measure vehicle emissions over a specified drive schedule in conjunction with subpart E of this part. Where the procedures of subpart E of this part differ from this subpart I, the provisions in this subpart I take precedence. (b) Collect samples of every pollutant for which an emission standard applies, unless specified otherwise. (c) This subpart covers the following test procedures: (1) The Federal Test Procedure (FTP), which includes the general driving cycle. This procedure is also used for measuring evaporative emissions. This may be called the conventional test since it was adopted with the earliest emission standards. (i) The FTP consists of one Urban Dynamometer Driving Schedule (UDDS) as specified in paragraph (a) of appendix I to 40 CFR part 86, followed by a 10-minute soak with the engine off and repeat driving through the first 505 seconds of the UDDS. Note that the UDDS represents about 7.5 miles of driving in an urban area. Engine startup (with all accessories turned off), operation over the initial UDDS, and engine shutdown make a complete cold-start test. The hot-start test consists of the first 505 seconds of the UDDS following the 10-minute soak and a hot-running portion of the UDDS after the first 505 seconds. The first 505 seconds of the UDDS is considered the transient portion; the remainder of the UDDS is considered the stabilized (or hot-stabilized) portion. The hot-stabilized portion for the hot-start test is generally measured during the cold-start test; however, in certain cases, the hot-start test may involve a second full UDDS following the 10-minute soak, rather than repeating only the first 505 seconds. See §§ 1066.815 and 1066.820. (ii) Evaporative emission testing includes a preconditioning drive with the UDDS and a full FTP cycle, including exhaust measurement, followed by evaporative emission measurements. In the three-day diurnal test sequence, the exhaust test is followed by a running loss test consisting of a UDDS, then two New York City Cycles as specified in paragraph (e) of appendix I to 40 CFR part 86, followed by another UDDS; see 40 CFR 86.134. Note that the New York City Cycle represents about 1.18 miles of driving in a city center. The running loss test is followed by a high-temperature hot soak test as described in 40 CFR 86.138 and a three-day diurnal emission test as described in 40 CFR 86.133. In the two-day diurnal test sequence, the exhaust test is followed by a low-temperature hot soak test as described in 40 CFR 86.138-96(k) and a two-day diurnal emission test as described in 40 CFR 86.133-96(p). (iii) Refueling emission tests for vehicles that rely on integrated control of diurnal and refueling emissions includes vehicle operation over the full FTP test cycle corresponding to the three-day diurnal test sequence to precondition and purge the evaporative canister. For non-integrated systems, there is a preconditioning drive over the UDDS and a refueling event, followed by repeated UDDS driving to purge the evaporative canister. The refueling emission test procedures are described in 40 CFR 86.150 through 86.157. (2) The US06 driving cycle is specified in paragraph (g) of appendix I to 40 CFR part 86. Note that the US06 driving cycle represents about 8.0 miles of relatively aggressive driving. (3) The SC03 driving cycle is specified in paragraph (h) of appendix I to 40 CFR part 86. Note that the SC03 driving schedule represents about 3.6 miles of urban driving with the air conditioner operating. (4) The hot portion of the LA-92 driving cycle is specified in paragraph (c) of appendix I to 40 CFR part 86. Note that the hot portion of the LA-92 driving cycle represents about 9.8 miles of relatively aggressive driving for commercial trucks. This driving cycle applies for heavy-duty vehicles above 10,000 pounds GVWR and at or below 14,000 pounds GVWR only for vehicles subject to Tier 3 standards. (5) The Highway Fuel Economy Test (HFET) is specified in appendix I to 40 CFR part 600. Note that the HFET represents about 10.2 miles of rural and freeway driving with an average speed of 48.6 mi/hr and a maximum speed of 60.0 mi/hr. See § 1066.840. (6) Cold temperature standards apply for NMOG+NO X (7) Emission measurement to determine air conditioning credits for greenhouse gas standards. In this optional procedure, manufacturers operate vehicles over repeat runs of the AC17 test sequence to allow for calculating credits as part of demonstrating compliance with CO 2 (8) The mid-temperature intermediate soak FTP is specified as the procedure for Partial Soak Emission Testing in Section E4.4 of California ARB's PHEV Test Procedures for plug-in hybrid electric vehicles, in Part II Section I.7 of California ARB's LMDV Test Procedures for other hybrid electric vehicles, and in Part II, Section B.9.1 and B.9.3 of California ARB's LMDV Test Procedures for other vehicles (both incorporated by reference, see § 1066.1010). (9) The early driveaway FTP is specified as the procedure for Quick Drive-Away Emission Testing in Section E4.5 of California ARB's PHEV Test Procedures for plug-in hybrid electric vehicles, in Part II Section I.8 of California ARB's LMDV Test Procedures for other hybrid electric vehicles, and in Part II, Section B.9.2 and B.9.4 of California ARB's LMDV Test Procedures for other vehicles (both incorporated by reference, see § 1066.1010). Additionally, vehicle speed may not exceed 0.0 mi/hr until 7.0 seconds into the driving schedule and vehicle speed may not exceed 2.0 mi/hr from 7.1 through 7.9 seconds. (10) The high-load PHEV engine starts US06 is specified in Section E7.2 of California ARB's PHEV Test Procedures using the cold-start US06 Charge-Depleting Emission Test (incorporated by reference, see § 1066.1010). (d) The following provisions apply for all testing: (1) Ambient temperatures encountered by the test vehicle must be (20 to 30) °C, unless otherwise specified. Where ambient temperature specifications apply before or between test measurements, the vehicle may be exposed to temperatures outside of the specified range for up to 10 minutes to account for vehicle transport or other actions to prepare for testing. The temperatures monitored during testing must be representative of those experienced by the test vehicle. For example, do not measure ambient temperatures near a heat source. (2) Do not operate or store the vehicle at an incline if good engineering judgment indicates that it would affect emissions. (3) If a test is void after collecting emission data from previous test segments, the test may be repeated to collect only those data points needed to complete emission measurements. You may combine emission measurements from different test runs to demonstrate compliance with emission standards. (4) Prepare vehicles for testing as described in § 1066.810. (e) The following figure illustrates the FTP test sequence for measuring exhaust and evaporative emissions: Figure 1 to Paragraph (e)—FTP Test Sequence [79 FR 23823, Apr. 28, 2014, as amended at 80 FR 9123, Feb. 19, 2015; 81 FR 74213, Oct. 25, 2016; 86 FR 34583, June 29, 2021; 89 FR 28213, Apr. 18, 2024] § 1066.805 Road-load power, test weight, and inertia weight class determination. (a) Simulate a vehicle's test weight on the dynamometer using the appropriate equivalent test weight shown in Table 1 of this section. Equivalent test weights are established according to each vehicle's test weight basis, as described in paragraph (b) of this section. Table 1 also specifies the inertia weight class corresponding to each equivalent test weight; the inertia weight class allows for grouping vehicles with a range of equivalent test weights. Table 1 follows: Table 1 of § 1066.805—Equivalent Test Weights (pounds) Test weight Equivalent test Inertia weight Up to 1062 1000 1000 1063 to 1187 1125 1000 1188 to 1312 1250 1250 1313 to 1437 1375 1250 1438 to 1562 1500 1500 1563 to 1687 1625 1500 1688 to 1812 1750 1750 1813 to 1937 1875 1750 1938 to 2062 2000 2000 2063 to 2187 2125 2000 2188 to 2312 2250 2250 2313 to 2437 2375 2250 2438 to 2562 2500 2500 2563 to 2687 2625 2500 2688 to 2812 2750 2750 2813 to 2937 2875 2750 2938 to 3062 3000 3000 3063 to 3187 3125 3000 3188 to 3312 3250 3000 3313 to 3437 3375 3500 3438 to 3562 3500 3500 3563 to 3687 3625 3500 3688 to 3812 3750 3500 3813 to 3937 3875 4000 3938 to 4125 4000 4000 4126 to 4375 4250 4000 4376 to 4625 4500 4500 4626 to 4875 4750 4500 4876 to 5125 5000 5000 5126 to 5375 5250 5000 5376 to 5750 5500 5500 5751 to 6250 6000 6000 6251 to 6750 6500 6500 6751 to 7250 7000 7000 7251 to 7750 7500 7500 7751 to 8250 8000 8000 8251 to 8750 8500 8500 8751 to 9250 9000 9000 9251 to 9750 9500 9500 9751 to 10250 10000 10000 10251 to 10750 10500 10500 10751 to 11250 11000 11000 11251 to 11750 11500 11500 11751 to 12250 12000 12000 12251 to 12750 12500 12500 12751 to 13250 13000 13000 13251 to 13750 13500 13500 13751 to 14000 14000 14000 (b) The test weight basis for non-MDPV heavy-duty vehicles is “adjusted loaded vehicle weight”. For all other vehicles, the test weight basis for establishing equivalent test weight is “loaded vehicle weight”. These load terms are defined in 40 CFR 86.1803. (c) For FTP, US06, SC03, New York City Cycle, HFET, and LA-92 testing, determine road-load forces for each test vehicle at speeds between 9.3 and 71.5 miles per hour. The road-load force must represent vehicle operation on a smooth, level road with no wind or calm winds, no precipitation, an ambient temperature of approximately 20 °C, and atmospheric pressure of 98.21 kPa. You may extrapolate road-load force for speeds below 9.3 mi/hr. [79 FR 23823, Apr. 28, 2016, as amended at 81 FR 74213, Oct. 25, 2016; 89 FR 18214, Apr. 18, 2024] § 1066.810 Vehicle preparation. (a) Include additional fittings and adapters as required to accommodate a fuel drain at the lowest point possible in the tank(s) as installed on the vehicle. (b) For preconditioning that involves loading an evaporative emission canister with butane, provide valving or other means to allow for purging and loading the canister. (c) For vehicles to be tested for running loss emissions (40 CFR 86.134), prepare the fuel tank for measuring temperature and pressure as specified in 40 CFR 86.107-98(e) and (f) and 40 CFR 86.134. Vapor temperature measurement is optional during the running loss test. (d) For vehicles to be tested for running loss emissions, prepare the exhaust system by sealing or plugging all detectable sources of exhaust gas leaks. Inspect or test the exhaust system to ensure that there are no leaks that would cause exhaust hydrocarbon emissions to be detected as running losses. (e) The following provisions apply for preconditioning steps to reduce nonfuel emissions to normal vehicle background levels for vehicles subject to Tier 3 evaporative emission standards under 40 CFR 86.1813: (1) You must notify us in advance if you plan to perform such preconditioning. This notice must include a detailed description of the intended procedures and any measurements or thresholds for determining when stabilization is complete. You need not repeat this notification for additional vehicle testing in the same or later model years as long as your preconditioning practice conforms to these procedures. (2) You may precondition a vehicle as described in paragraph (e)(1) of this section only within 12 months after the vehicle's original date of manufacture, except that you may ask us to approve further preconditioning steps for any testing to address identifiable sources of nonfuel emissions beyond what would generally occur with an appropriately aged in-use vehicle. For example, you may clean up fluid leaks and you may perform further off-vehicle preconditioning for tires or other replacement parts that are less than 12 months old. You may also replace the spare tire with an aged spare tire, and you may replace the windshield washer fluid with water. § 1066.815 Exhaust emission test procedures for FTP testing. (a) General. (b) PM sampling options. (1) You may collect a separate PM sample for transient and stabilized portions of the cold-start UDDS and the hot-start UDDS. This may either be done by sampling with three bags or four bags. You may omit the stabilized portion of the hot-start test (bag 4) and use the stabilized portion of the cold-start test (bag 2) in its place. (2) You may collect PM on one filter over the cold-start UDDS and on a separate filter over the hot-start UDDS. (3) You may collect PM on one filter over the cold-start UDDS (bag 1 and bag 2) and on a separate filter over the 867 seconds of the stabilized portion of the cold-start UDDS and the first 505 seconds of the hot-start UDDS (bag 2 and bag 3). Note that this option involves duplicate measurements during the stabilized portion of the cold-start UDDS. (4) You may collect PM on a single filter over the cold-start UDDS and the first 505 seconds of the hot-start UDDS using one of the following methods: (i) Adjust your sampling system flow rate over the filter to weight the filter face velocity over the three intervals of the FTP based on weighting targets of 0.43 for bag 1, 1.0 for bag 2, and 0.57 for bag 3. (ii) Maintain a constant sampling system flow rate over the filter for all three intervals of the FTP by increasing overall dilution ratios for bag 1 and bag 3. To do this, reduce the sample flow rate from the exhaust (or diluted exhaust) such that the value is reduced to 43% and 57%, respectively, of the bag 2 values. For constant-volume samplers, this requires that you decrease the dilute exhaust sampling rate from the CVS and compensate for that by increasing the amount of secondary dilution air. (5) You may collect PM on a single filter over the cold-start UDDS and the full hot-start UDDS using one of the following methods: (i) Adjust your sampling system flow rate over the filter to weight the filter face velocity based on weighting targets of 0.75 for the cold-start UDDS and 1.0 for the hot-start UDDS. (ii) Maintain a constant sampling system flow rate over the filter for both the cold-start and hot-start UDDS by increasing the overall dilution ratio for the cold-start UDDS. To do this, reduce the sample flow rate from the exhaust (or diluted exhaust) such that the value is reduced to 75% of the hot-start UDDS value. For constant-volume samplers, this requires that you decrease the dilute exhaust sampling rate from the CVS and compensate for that by increasing the amount of secondary dilution air. (c) Gaseous sampling options. (1) You may collect a single sample for a full UDDS (cold-start or hot-start). (2) You may sample emissions separately for transient and stabilized portions of any UDDS. (3) You may omit the stabilized portion of the hot-start test (bag 4) and use the stabilized portion of the cold-start test (bag 2) in its place. (d) Test sequence. (1) Take the following steps for the cold-start test: (i) Precondition the vehicle as described in § 1066.816. Initiate the cold-start test following the 12 to 36 hour soak period. (ii) Simultaneously start any electronic integrating devices, continuous data recording, and batch sampling before attempting to start the engine. Initiate the sequence of points in the test cycle when the engine starts. Place the vehicle in gear 15 seconds after engine starting, which is 5 seconds before the first acceleration. (iii) At the end of the deceleration scheduled to occur 505 seconds into the cold-start UDDS, simultaneously switch all the sample flows from the cold-start transient interval to the stabilized interval, stopping all cold-start transient interval sampling and recording, including background sampling. Reset integrating devices for the stabilized interval and indicate the end of the cold-start interval in the recorded data. Operate the vehicle over the remainder of the UDDS. Turn the engine off 2 seconds after the end of the last deceleration in the stabilized interval (1,369 seconds after the start of the driving schedule). (iv) Five seconds after the engine stops running, stop all stabilized interval sampling and recording, including background sampling. Stop any integrating devices for the stabilized interval and indicate the end of the stabilized interval in the recorded data. Note that the 5 second delay is intended to account for sampling system transport. (2) Take the following steps for the hot-start test: (i) Initiate the hot-start test (9 to 11) minutes after the end of the sample period for the cold-start UDDS. (ii) Repeat the steps in paragraph (d)(1)(ii) of this section. Operate the vehicle over the first 505 seconds of the UDDS. For tests that do not include bag 4 operation, turn off the engine and simultaneously stop all hot-start sampling and recording, including background sampling, and any integrating devices at the end of the deceleration scheduled to occur 505 seconds into the hot-start UDDS. (iii) To include bag 4 measurement, operate the vehicles over the remainder of the UDDS and conclude the testing as described in paragraphs (d)(1)(iii) and (iv) of this section. (3) This completes the procedure for measuring FTP exhaust emissions. See § 1066.801 and subpart J of this part for continuing the test sequence to measure evaporative or refueling emissions. [79 FR 23823, Apr. 28, 2014, as amended at 80 FR 9124, Feb. 19, 2015; 81 FR 74213, Oct. 25, 2016; 88 FR 4709, Jan. 24, 2023] § 1066.816 Vehicle preconditioning for FTP testing. Precondition the test vehicle before the FTP exhaust measurement as described in 40 CFR 86.132. § 1066.820 Composite calculations for FTP exhaust emissions. (a) Determine the mass of exhaust emissions of each pollutant for each FTP test interval as described in § 1066.605. (b) Calculate the final composite gaseous test results as a mass-weighted value, e [emission]-FTPcomp Where: m c D ct D cs m h D ht D hs D hs D cs (c) Calculate the final composite PM test results as a mass-weighted value, e PM-FTPcomp, (1) Use the following equation for PM measured as described in § 1066.815(b)(1), (2), or (3): Where: m PM-cUDDS m PM-hUDDS (2) Use the following equation for PM measured as described in § 1066.815(b)(4): Where: m PM (3) Use the following equation for PM measured as described in § 1066.815(b)(5): Where: m PM [79 FR 23823, Apr. 28, 2016, as amended at 81 FR 74214, Oct. 25, 2016] § 1066.830 Supplemental Federal Test Procedures; overview. Sections 1066.831 and 1066.835 describe the detailed procedures for the Supplemental Federal Test Procedure (SFTP). This testing applies for Tier 3 vehicles subject to the SFTP standards in 40 CFR 86.1811-17 or 86.1816-18. The SFTP test procedure consists of FTP testing and two additional test elements—a sequence of vehicle operation with more aggressive driving and a sequence of vehicle operation that accounts for the impact of the vehicle's air conditioner. Tier 4 vehicles subject to 40 CFR 86.1811-27 must meet standards for each individual driving cycle. (a) The SFTP standard applies as a composite representing the three test elements. The emission results from the aggressive driving test element (§ 1066.831), the air conditioning test element (§ 1066.835), and the FTP test element (§ 1066.820) are analyzed according to the calculation methodology and compared to the applicable SFTP emission standards as described in 40 CFR part 86, subpart S. (b) The test elements of the SFTP may be run in any sequence that includes the specified preconditioning steps. [89 FR 28215, Apr. 18, 2024] § 1066.831 Exhaust emission test procedures for aggressive driving. (a) This section describes how to test using the US06 or LA-92 driving schedule. The US06 driving schedule can be divided into two test intervals—the US06 City cycle comprises the combined portions of the cycle from 1 to 130 seconds and from 495 to 596 seconds, and the US06 Highway cycle comprises the portion of the cycle between 130 and 495 seconds. See § 1066.801 for further information on the driving schedules. (b) Take the following steps to precondition vehicles for testing under this section: (1) Drain and refill the vehicle's fuel tank(s) in any of the following cases: (i) For aggressive-driving tests that do not follow FTP or HFET testing. (ii) For a test element that starts more than 72 hours after the most recent FTP or HFET measurement (with or without evaporative emission measurements). (iii) For testing in which the test vehicle has not remained in an area where ambient temperatures were within the range specified for testing since the previous FTP or HFET. (2) Keep ambient temperatures within the ranges specified for test measurements throughout the preconditioning sequence. (3) Warm up the vehicle to a stabilized condition as follows: (i) Push or drive the vehicle onto the dynamometer. (ii) Operate the vehicle one time over one of the driving schedules specified in this paragraph (b)(3)(ii). You may ask us to use a particular preconditioning driving schedule if that is related to fuel effects on adaptive memory systems. For our testing, we will generally operate the vehicle over the same preconditioning cycle that will be used for testing in this section. You may exercise your sampling equipment, but you may not determine emissions results during preconditioning. Choose from the following driving schedules: (A) The first 505 seconds of the UDDS (bag 1). (B) The last 867 seconds of the UDDS (bag 2). (C) The HFET driving schedule. (D) US06 driving schedule or, for heavy-duty vehicles at or below 10,000 pounds GVWR with a power-to-weight ratio at or below 0.024 hp/lbm, just the highway portion of the US06 driving schedule. (E) The SC03 driving schedule. (F) The LA-92 driving schedule. (G) The Hot LA-92 driving schedule. (4) Allow the vehicle to idle for (1 to 2) minutes. This leads directly into the test measurements described in paragraph (c) of this section. (c) For testing involving the full US06 driving schedule, you may collect emissions from separate city and highway test intervals (see 40 CFR part 600), or you may collect emissions over the full US06 driving schedule as a single test interval. Take the following steps to measure emissions over separate city and highway test intervals: (1) At 130 seconds, simultaneously stop all US06 City, and start all US06 Highway sampling, recording, and integrating (including background sampling). At 136 seconds (before the acceleration), record the measured dynamometer roll revolutions. (2) At 495 seconds, simultaneously stop all US06 Highway, and start all US06 City sampling, recording, and integrating (including background sampling). At 500 seconds (before the acceleration), record the measured dynamometer roll revolutions. (3) Except as specified in paragraph (c)(4) of this section, treat the emissions from the first and second portions of the US06 City test interval as a single sample. (4) If you collect gaseous emissions over separate city and highway test intervals, you may still collect PM over the full US06 driving schedule as a single test interval. If you do this, calculate a composite dilution factor based on city and highway emissions using Eq. 1066.610-4 to show that you meet the dilution factor requirements of § 1066.110(b)(2)(iii)(B). (d) For diesel-fueled vehicles, measure THC emissions on a continuous basis. For separate measurement of the city and highway test intervals as described in paragraph (c) of this section, perform separate calculations for each portion of the test cycle. (e) Follow the exhaust emission measurement procedures specified in §§ 1066.410 through 1066.425, subject to the following exceptions and additional provisions: (1) Following the preconditioning specified in paragraph (b) of this section, place the vehicle in gear and simultaneously start sampling and recording. Begin the first acceleration 5 seconds after placing the vehicle in gear. (2) Operate the vehicle over the full US06 driving schedule, with the following exceptions that apply only for Tier 3 vehicles: (i) For heavy-duty vehicles above 10,000 pounds GVWR, operate the vehicle over the Hot LA-92 driving schedule. (ii) Heavy-duty vehicles at or below 10,000 pounds GVWR with a power-to-weight ratio at or below 0.024 hp/pound may be certified using only the highway portion of the US06 driving schedule as described in 40 CFR 86.1816. (3) Turn the engine off 2 seconds after the end of the last deceleration. Five seconds after the engine stops running, stop all sampling and recording, including background sampling. Stop any integrating devices and indicate the end of the test cycle in the recorded data. Note that the 5 second delay is intended to account for sampling system transport. (4) Correct calculated NO X [79 FR 23823, Apr. 28, 2014, as amended at 80 FR 9124, Feb. 19, 2015; 88 FR 4709, Jan. 24, 2023; 89 FR 28215, Apr. 18, 2024] § 1066.835 Exhaust emission test procedure for SC03 emissions. This section describes how to test using the SC03 driving schedule (see § 1066.801). This procedure is designed to determine gaseous exhaust emissions while simulating an urban trip on a hot summer day. The provisions of 40 CFR part 86 and 40 CFR part 600 waive SC03 testing for some vehicles; in those cases, calculate SFTP composite emissions by adjusting the weighting calculation as specified in 40 CFR part 86, subpart S. (a) Drain and refill the vehicle's fuel tank(s) if testing starts more than 72 hours after the most recent FTP or HFET measurement (with or without evaporative emission measurements). (b) Keep the vehicle in an environment meeting the conditions described in paragraph (f) of this section throughout the preconditioning sequence. (c) Warm up the vehicle to a stabilized condition as follows: (1) Push or drive the test vehicle onto the dynamometer. (2) Close the vehicle's windows before testing. (3) The test cell and equipment must meet the specifications in paragraph (e) of this section. Measure and control ambient conditions as specified in paragraph (f) of this section. (4) Set the vehicle's air conditioning controls by selecting A/C mode and “maximum”, setting airflow to “recirculate” (if so equipped), selecting the highest fan setting, and turning the A/C temperature to full cold (or 72 °F for automatic systems). Turn the control to the “on” position before testing so the air conditioning system is active whenever the engine is running. (5) Perform a preconditioning drive by operating the test vehicle one time over the first 505 seconds of the UDDS (bag 1), the last 867 seconds of the UDDS (bag 2), or the SC03 driving schedule. If the air conditioning test sequence starts more than 2 hours after a different exhaust emission test, you may instead operate the vehicle one time over the full UDDS. (6) Following the preconditioning drive, turn off the test vehicle and the vehicle cooling fan(s) and allow the vehicle to soak for (9 to 11) minutes. (d) Follow the exhaust emission measurement procedures specified in §§ 1066.410 through 1066.425, subject to the following exceptions and additional provisions: (1) Place the vehicle in gear 15 seconds after engine starting, which is 3 seconds before the first acceleration. Follow the SC03 driving schedule. (2) Turn the engine off 2 seconds after the end of the last deceleration. Five seconds after the engine stops running, stop all sampling and recording, including background sampling. Stop any integrating devices any indicate the end of the test cycle in the recorded data. Note that the 5 second delay is intended to account for sampling system transport. (3) Correct calculated NO X (e) The following requirements apply for the test cell and cooling fan configuration: (1) Minimum test cell size. (2) Vehicle frontal air flow. (f) Maintain ambient conditions as follows: (1) Ambient temperature and humidity. (2) Conditions before testing. (3) Solar heat load. (i) You may use a metal halide lamp, a sodium lamp, or a quartz halogen lamp with dichroic mirrors as a radiant energy emitter. We may also approve the use of a different type of radiant energy emitter if you demonstrate that it meets the requirements of this section. (ii) We recommend achieving radiant heating with spectral distribution characteristics as described in the following table: Table 1 of § 1066.835—Recommended Spectral Distribution Band width (nm) Percent of total spectrum Lower limit (%) Upper limit (%) <320 a 0 320-400 0 7 400-780 45 55 >780 35 53 a (iii) Determine radiant energy intensity experienced by the vehicle as the average value between two measurements along the vehicle's centerline, one at the base of the windshield and the other at the bottom of the rear window (or equivalent location for vehicles without a rear window). This value must be (850 ± 45) W/m 2 (A) Sensitivity of 9 microvolts per W/m 2 (B) Response time of 5 seconds. For purposes of this requirement, “response time” means the time for the instrument to reach 95 percent of its equilibrium response after a step change in radiant intensity. (C) Cosine response error of no more than ±1% for 0-70 degree zenith angles. The cosine response error is the percentage difference between the intensity measured at a given angle and a reference value, where the reference value is the intensity predicted from the zero-degree intensity and the cosine of the incident angle. (D) When comparing measured values for radiant energy to reference values, each measured value over the full range of measurement may not deviate from the corresponding reference value by more than ±0.5% of the analyzer range's maximum value. (iv) Check the uniformity of radiant energy intensity at least every 500 hours of emitter usage or every 6 months, whichever is sooner, and after any major modifications affecting the solar simulation. Determine uniformity by measuring radiant energy intensity using instruments that meet the specifications described in paragraph (f)(3)(iii) of this section at each point of a 0.5 m grid over the vehicle's full footprint, including the edges of the footprint, at an elevation 1 m above the floor. Measured values of radiant energy intensity must be between (722 and 978) W/m 2 [79 FR 23823, Apr. 28, 2014, as amended at 80 FR 9124, Feb. 19, 2015; 81 FR 74214, Oct. 25, 2016; 86 FR 34584, June 29, 2021; 88 FR 4709, Jan. 24, 2023] § 1066.840 Highway fuel economy test procedure. This section describes the procedure for the highway fuel economy test (HFET). This test involves emission sampling and fuel economy measurement for certain vehicles as described in 40 CFR part 86, subpart S, and in 40 CFR part 600. See § 1066.801 for further information on the driving schedules. Follow the exhaust emission measurement procedures specified in §§ 1066.410 through 1066.425, subject to the following exceptions and additional provisions: (a) Perform the HFET immediately following the FTP when this is practical. If the HFET procedure starts more than 3 hours after an FTP (including evaporative emission measurements, if applicable), operate it over one UDDS to precondition the vehicle. We may approve additional preconditioning in unusual circumstances. (b) Operate the vehicle over the HFET driving schedule for preconditioning. Allow the vehicle to idle for 15 seconds (with the vehicle in gear), then start a repeat run of the HFET driving schedule and simultaneously start sampling and recording. (c) Turn the engine off at the end of the HFET driving schedule and stop all sampling and recording, including background. Stop any integrating devices and indicate the end of the test cycle in the recorded data. § 1066.845 AC17 air conditioning efficiency test procedure. (a) Overview. 2 (b) Test cell. (c) Ambient conditions. (d) Interior air temperature measurement. (e) Air conditioning system settings. (1) For automatic systems, set the temperature control to 72 °F (22 °C). (2) For manual systems, select A/C mode, set the temperature to full cold and “maximum”, set airflow to “recirculate” (if so equipped), and select the highest fan setting. During the first idle period of the SC03 driving schedule (between 186 and 204 seconds), reduce the fan speed setting to nominally 50% of maximum fan speed, set airflow to “fresh air” (if so equipped), and adjust the temperature setting to target a temperature of 55 °F (13 °C) at the dashboard air outlet. Maintain these settings for the remainder of the test. You may rely on prior temperature measurements to determine the temperature setting; however, if the system is unable to meet the 55 °F (13 °C) target, you may instead set airflow to “fresh air” and temperature to full cold. If the vehicle is equipped with technology that defaults to recirculated air at ambient temperatures above 75 °F (22 °C), that technology should remain enabled throughout the test; this may mean not setting the airflow to “recirculate” at the start and not setting the airflow to “fresh air” during the first idle period of the SC03 driving schedule. Except as specified in paragraph (e)(3) of this section, use good engineering judgment to apply the settings described in this paragraph (e)(2) equally throughout the vehicle if there are separate controls for different zones (such as rear air conditioning). (3) If the air conditioning system is designed with parameters that switch back to a default setting at key-off, perform testing in that default condition. If the air conditioning system includes any optional equipment or user controls not addressed in this paragraph (e), the manufacturer should ask us for preliminary approval to determine the appropriate settings for testing. (f) Test procedure. (1) Prepare each test vehicle for a series of tests according to 40 CFR 86.132-00(a) through (g). If the vehicle has been tested within the last 36 hours concluding with a 12 to 36 hour soak, continue to paragraph (f)(2) of this section; otherwise perform an additional UDDS preconditioning cycle that concludes with a 12 to 36 hour soak. You may use a forced cooldown system to bring critical vehicle temperatures to within soak temperature limits. Critical temperatures include transmission oil, engine oil, engine coolant, and cabin air temperatures. (2) Open the vehicle's windows and operate the vehicle over a preconditioning UDDS with no solar heating and with the air conditioning off. At the end of the preconditioning drive, turn off the test vehicle and all cooling fans. (3) Turn on solar heating within one minute after turning off the engine. Once the solar energy intensity reaches 805 W/m 2 (4) Turn the air conditioning control to the “on” position before testing so the air conditioning system is active whenever the engine is running. Place the vehicle in gear 15 seconds after engine starting, which is 3 seconds before the first acceleration. At the end of the driving schedule, simultaneously switch all the sampling, recording, and integrating from SC03 to HFET, including background sampling. Indicate the end of the test cycle in the recorded data. Record the measured dynamometer roll revolutions corresponding to the SC03 driving schedule. (5) Directly following the SC03 driving schedule, operate the vehicle over the HFET driving schedule. Turn the vehicle off at the end of the driving schedule and simultaneously stop all sampling, recording, and integrating, including background sampling. Indicate the end of the test cycle in the recorded data. Record the measured dynamometer roll revolutions corresponding to the HFET drive schedule. Turn off the solar heating. (6) Allow the vehicle to remain on the dynamometer for (10 to 15) minutes after emission sampling has concluded. Repeat the testing described in paragraphs (f)(1) through (5) of this section and turn off the vehicle's air conditioner and the solar heating throughout the test run. The windows may be open or closed. (g) Calculations. 2 (2) Calculate separate composite mass-weighted emissions of CO 2 e CO2-AC17compAC[status] Where: m SC03 D SC03 m HFET D HFET (3) Calculate the incremental CO 2 2 e CO2-AC17compACon, 2 e CO2-AC17compACoff. (h) Record information for each test as specified in § 1066.695. Emission results and the results of all calculations must be reported for each phase of the test. The manufacturer must also report the following information for each vehicle tested: interior volume, climate control system type and characteristics, refrigerant used, compressor type, and evaporator/condenser characteristics. [79 FR 23823,Apr. 28, 2014, as amended at 79 FR 36658, June 30, 2014; 80 FR 9124, Feb. 19, 2015; 88 FR 4710, Jan. 24, 2023] Subpart J—Evaporative Emission Test Procedures § 1066.901 Applicability and general provisions. This subpart describes how to measure evaporative and refueling emissions from test vehicles. The provisions of §§ 1066.910 through 1066.930 include general provisions for equipment and calculations related to evaporative and refueling emissions. The provisions of §§ 1066.950 through 1066.985 describe provisions that apply specifically to motor vehicles subject to standards under 40 CFR part 86, subpart S, or 40 CFR part 1037. Test Equipment and Calculations for Evaporative and Refueling Emissions § 1066.910 SHED enclosure specifications. Enclosures for evaporative and refueling emissions must meet the specifications described in 40 CFR 86.106-96, 86.107-96(a), and 86.107-98(a). § 1066.915 Enclosures; auxiliary systems and equipment. Enclosures for evaporative and refueling emissions must be equipped with fans, blowers, and measurement and data recording equipment as described in 40 CFR 86.107-98(b) through (h) and (j). § 1066.920 Enclosure calibrations. Enclosures for evaporative and refueling emissions must meet the calibration specifications described in 40 CFR 86.116-94 and 86.117-96. § 1066.925 Enclosure calculations for evaporative and refueling emissions. Calculate emissions for evaporative emissions as described in 40 CFR 86.143-96. Calculate emissions for refueling emissions as described in 40 CFR 86.143-96 and 86.156-98. § 1066.930 Equipment for point-source measurement of running losses. For point-source measurement of running loss emissions, use equipment meeting the specifications in 40 CFR 86.107-96(i). [86 FR 34585, June 29, 2021] Evaporative and Refueling Emission Test Procedures for Motor Vehicles § 1066.950 Fuel temperature profile. Develop fuel temperature profiles for running loss testing as described in 40 CFR 86.129-94(d). § 1066.955 Diurnal emission test. Test vehicles for diurnal emissions as described in 40 CFR 86.133-96. § 1066.960 Running loss test. Test vehicles for running loss emissions as described in 40 CFR 86.134-96. § 1066.965 Hot soak test. Test vehicles for hot soak emissions as described in 40 CFR 86.138-96. § 1066.970 Refueling test for liquid fuels. Except as described in § 1066.975, test vehicles for refueling emissions as described in 40 CFR 86.150-98, 86.151-98, 86.152-98, and 86.154-98. Keep records as described in 40 CFR 86.155-98. § 1066.971 Vehicle and canister preconditioning for the refueling test. Precondition vehicles for the refueling emission test as described in 40 CFR 86.153-98. § 1066.975 Refueling test for LPG. For vehicles designed to operate on liquefied petroleum gas, measure refueling emissions as described in 40 CFR 86.157-98. § 1066.980 Fuel dispensing spitback procedure. Test vehicles for spitback emissions as described in 40 CFR 86.146-96. § 1066.985 Fuel storage system leak test procedure. (a) Scope. (b) Measurement principles. (c) Measurement equipment. (1) Pressure, temperature, and flow sensors must be calibrated with NIST-traceable standards. (2) Correct flow measurements to standard reference conditions. (3) Leak test equipment must have the ability to pressurize fuel storage systems to at least 4.1 kPa and have an internal leak rate of less than 0.20 standard liters per minute. (4) You must be able to attach the test equipment to the vehicle without permanent alteration of the fuel storage or evaporative emission control systems. For any testing that involves pressurizing the fuel system and detecting leaks at access points away from the fuel fill pipe, the gas cap must be installed in the production configuration. For the test point at or near the fuel fill pipe, attaching the test equipment may involve adding an extension to the fuel fill pipe that incorporates the access point to the fuel system. If the extension apparatus has a fixed cap, the vehicle's gas cap must be tested separately as described in paragraph (d)(9) of this section. This separate testing is not required if the extension apparatus incorporates the vehicle's gas cap. (5) The point of attachment to the fuel storage system must allow pressurization to test system integrity of the fuel tank and of fuel lines and vapor lines reaching up to and including the gas cap and the evaporative canister. The evaporative system test port available on some vehicles is an example of an effective attachment point. (d) Leak test procedure. (1) Refuel vehicle to 40% of its nominal fuel tank capacity. (2) Soak the vehicle for 6 to 24 hours at a temperature between (20 and 30) °C; record this setpoint temperature and maintain temperatures throughout the leak test at this setpoint temperature within a tolerance ±2 °C. (3) Before performing the test, purge the fuel storage system of any residual pressure, bringing the system into equilibrium with ambient pressure. (4) Seal the evaporative canister's vent to atmosphere and ensure that the vehicle's purge valve is closed. (5) Attach the leak test equipment to the vehicle. (6) Pressurize the fuel storage system with N 2 (7) Maintain gas flow through the system for at least 180 seconds, ensuring that the flow reading is stable for an effective leak diameter of ±0.002 inches. (8) Use the following equation, or a different equation you develop based on good engineering judgment, to calculate the effective leak diameter, d eff Where: d eff Q N2 3 p in p atmos SG N2 2 T Example: Q N2 −5 3 p in p atmos SG N2 T d eff (9) Repeat the test described in this paragraph (d) for each access point described in the application for certification. Use each test result (without averaging) to determine whether the vehicle passes the leak standard. (10) Gas caps may need to be tested separately for leaks as described in paragraph (c)(4) of this section. Test the gas caps using commercially available flow equipment such as that used for inspection-and-maintenance programs for motor vehicles to determine a leak rate in cubic centimeters per minute resulting from a sustained tank pressure of 7.5 kPa. Correct the leak rate to standard reference conditions, based on the measured leak rate corresponding to atmospheric pressure. The corrected leak value may not exceed 60 cubic centimeters per minute. (11) You may use special or alternative test procedures as described in 40 CFR 1065.10(c). (e) Equipment calibration. [79 FR 23823, Apr. 28, 2014, as amended at 80 FR 9124, Feb. 19, 2015; 81 FR 74215, Oct. 25, 2016] Subpart K—Definitions and Other Reference Material § 1066.1001 Definitions. The definitions in this section apply to this part. The definitions apply to all subparts unless we note otherwise. Other terms have the meaning given in 40 CFR part 1065. The definitions follow: Average Bag 1 Bag 2 Bag 3 Bag 4 Base inertia C 1 equivalent 1 1 3 8 1 1 Charge-depleting Charge-sustaining Driving schedule Duty cycle FTP (1) The test cycle consisting of one UDDS as specified in paragraph (a) of Appendix I of 40 CFR part 86, followed by a 10-minute soak with the engine off and repeat driving through the first 505 seconds of the UDDS. See § 1066.801(c)(1). (2) The entire test procedure for measuring exhaust and/or evaporative emissions as described in § 1066.801(c). Footprint HFET Hot LA-92 LA-92 Nonmethane organic gas (NMOG) Parts-per-million (ppm) 1 Road-load coefficients v v v 2 SC03 Standard reference conditions (1) Standard pressure (2) Standard temperature Supplemental FTP (SFTP) Test interval Test weight UDDS US06 Unloaded coastdown We (us, our) [79 FR 23823, Apr. 28, 2014, as amended at 80 FR 9124, Feb. 19, 2015; 88 FR 4710, Jan. 24, 2023; 89 FR 28215, Apr. 18, 2024] § 1066.1005 Symbols, abbreviations, acronyms, and units of measure. The procedures in this part generally follow either the International System of Units (SI) or the United States customary units, as detailed in NIST Special Publication 811, which we incorporate by reference in § 1066.1010. See 40 CFR 1065.20 for specific provisions related to these conventions. This section summarizes the way we use symbols, units of measure, and other abbreviations. (a) Symbols for quantities. Table 1 of § 1066.1005—Symbols for Quantities Symbol Quantity Unit Unit symbol Unit in terms of SI base units α atomic hydrogen to carbon ratio mole per mole mol/mol 1. A area square meter m 2 m 2 A vehicle frictional load pound force or newton lbf or N m·kg·s − 2 a g acceleration of Earth's gravity meters per second squared m/s 2 m·s − 2 A m calculated vehicle frictional load pound force or newton lbf or N m·kg·s − 2 a 0 intercept of least squares regression. a 1 slope of least squares regression. a acceleration feet per second squared or meters per second squared ft/s 2 2 m·s - 2 B vehicle load from drag and rolling resistance pound force per mile per hour or newton second per meter lbf/(mi/hr) or N·s/m kg·s - 1 β ratio of diameters meter per meter m/m 1. β atomic oxygen to carbon ratio mole per mole mol/mol 1. c conversion factor. C vehicle-specific aerodynamic effects pound force per mile per hour squared or newton-second squared per meter squared lbf/(mi/hr) 2 2 2 m - 1 C # number of carbon atoms in a molecule C # number of carbon atoms in a molecule C #. C d discharge coefficient. C d A drag area meter squared m 2 m 2 C f flow coefficient. C p heat capacity at constant pressure joule per kelvin J/K m 2 - 2 - 1 C v heat capacity at constant volume joule per kelvin J/K m 2 - 2 - 1 d diameter meters m m. D distance miles or meters mi or m m. D slope correlation pound force per mile per hour squared or newton second squared per meter squared lbf/(mi/hr) 2 2 2 m − 2 DF dilution factor. 1. e mass weighted emission result grams/mile g/mi. F force pound force or newton lbf or N kg·s − 2 ƒ frequency hertz Hz s − 1 ƒn angular speed (shaft) revolutions per minute r/min π·30·s − 1 FC friction compensation error horsepower or watt W m 2 − 3 FR road-load force pound force or newton lbf or N kg·s − 2 γ ratio of specific heats (joule per kilogram kelvin) per (joule per kilogram kelvin) (J/(kg·K))/(J/(kg·K)) 1. H ambient humidity grams water vapor per kilogram dry air g H 2 g H 2 Δ h change in height meters m m. I inertia pound mass or kilogram lbm or kg kg. I current ampere A A. i indexing variable. IR inertia work rating. K correction factor 1. K v calibration coefficient m 4 0.5 m 4 − 1 0.5 µ viscosity, dynamic pascal second Pa·s m − 1 − 1 M molar mass gram per mole g/mol 10-3·kg·mol − 1 M e effective mass kilogram kg kg. m mass pound mass or kilogram lbm or kg kg. N total number in series. n total number of pulses in a series. p pressure pascal Pa m − 1 − 2 Δ p differential static pressure pascal Pa m − 1 − 2 p d saturated vapor pressure at ambient dry bulb temperature kilopascal kPa m − 1 − 1 PF penetration fraction. ρ mass density kilogram per cubic meter kg/m 3 m − 3 R dynamometer roll revolutions revolutions per minute rpm π·30 − 1 − 1 r ratio of pressures pascal per pascal Pa/Pa 1. r 2 coefficient of determination. Re # Reynolds number. RF response factor. RH relative humidity. S Sutherland constant kelvin K K. SEE standard error of the estimate. SG specific gravity. Δ s distance traveled during measurement interval meters m m. T absolute temperature kelvin K K. T Celsius temperature degree Celsius °C K−273.15. T torque (moment of force) newton meter N·m m 2 - 2 t time hour or second hr or s s. Δ t time interval, period, 1/frequency second s s. U voltage volt V m 2 - 3 - 1 v speed miles per hour or meters per second mi/hr or m/s m·s - 1 V volume cubic meter m 3 m 3 V flow volume rate cubic feet per minute or cubic meter per second ft 3 3 m 3 − 1 VP volume percent. x concentration of emission over a test interval part per million ppm. y generic variable. Z compressibility factor. (b) Symbols for chemical species. Table 2 to Paragraph ( b Symbol Species CH 4 methane. CH 3 methanol. CH 2 formaldehyde. C 2 4 acetaldehyde. C 2 5 ethanol. C 2 6 ethane. C 3 7 propanol. C 3 8 propane. C 4 10 butane. C 5 12 pentane. CO carbon monoxide. CO 2 carbon dioxide. H 2 water. HC hydrocarbon. N 2 molecular nitrogen. NMHC nonmethane hydrocarbon. NMHCE nonmethane hydrocarbon equivalent. NMOG nonmethane organic gas. NO nitric oxide. NO 2 nitrogen dioxide. NO X oxides of nitrogen. N 2 nitrous oxide. O 2 molecular oxygen. OHC oxygenated hydrocarbon. PM particulate matter. THC total hydrocarbon. THCE total hydrocarbon equivalent. (c) Superscripts. Table 3 of § 1066.1005—Superscripts Superscript Meaning overbar (such as y arithmetic mean. overdot (such as y quantity per unit time. (d) Subscripts. Table 4 of § 1066.1005—Subscripts Subscript Meaning 0 reference. abs absolute quantity. AC17 air conditioning 2017 test interval. act actual or measured condition. actint actual or measured condition over the speed interval. adj adjusted. air air, dry. atmos atmospheric. b base. bkgnd background. c cold. comp composite. cor corrected. cs cold stabilized. ct cold transient. cUDDS cold-start UDDS. D driven. dew dewpoint. dexh dilute exhaust quantity. dil dilute. e effective. emission emission specie. error error. EtOH ethanol. exh raw exhaust quantity. exp expected quantity. fil filter. final final. flow flow measurement device type. gas gaseous. h hot. HFET highway fuel economy test. hs hot stabilized. ht hot transient. hUDDS hot-start UDDS. i an individual of a series. ID driven inertia. in inlet. int intake. init initial quantity, typically before an emission test. IT target inertia. liq liquid. max the maximum ( i.e., meas measured quantity. mix dilute exhaust gas mixture. out outlet. PM particulate matter. record record. ref reference quantity. rev revolution. roll dynamometer roll. s settling. s slip. s stabilized. sat saturated condition. SC03 air conditioning driving schedule. span span quantity. sda secondary dilution air. std standard conditions. T target. t throat. test test quantity. uncor uncorrected quantity. w weighted. zero zero quantity. (d) Subscripts. Subscript Quantity 0 reference. abs absolute quantity. AC17 air conditioning 2017 test interval. act actual or measured condition. actint actual or measured condition over the speed interval. adj adjusted. air air, dry. atmos atmospheric. b base. bkgnd background. c cold. comp composite. cor corrected. cs cold stabilized. ct cold transient. cUDDS cold-start UDDS. D driven. dew dewpoint. dexh dilute exhaust quantity. dil dilute. e effective. emission emission specie. error error. EtOH ethanol. exh raw exhaust quantity. exp expected quantity. fil filter. final final. flow flow measurement device type. gas gaseous. h hot. HFET highway fuel economy test. hs hot stabilized. ht hot transient. hUDDS hot-start UDDS. i an individual of a series. ID driven inertia. in inlet. int intake. init initial quantity, typically before an emission test. IT target inertia. liq liquid. max the maximum (i.e. peak) value expected at the standard over a test interval; not the maximum of an instrument range. meas measured quantity. mix dilute exhaust gas mixture. out outlet. PM particulate matter. record record. ref reference quantity. rev revolution. roll dynamometer roll. s settling. s slip. s stabilized. sat saturated condition. SC03 air conditioning driving schedule. span span quantity. sda secondary dilution air. std standard conditions. T target. t throat. test test quantity. uncor uncorrected quantity. w weighted. zero zero quantity. (e) Other acronyms and abbreviations. Table 5 of § 1066.1005—Other Acronyms and Abbreviations Acronym Meaning A/C air conditioning. AC17 air conditioning 2017 test interval. ALVW adjusted loaded vehicle weight. ASME American Society of Mechanical Engineers. CFR Code of Federal Regulations. CFV critical-flow venturi. CNG compressed natural gas. CVS constant-volume sampler. EPA Environmental Protection Agency. ETW equivalent test weight. EV electric vehicle. FID flame-ionization detector. FTP Federal test procedure. GC gas chromatograph. GEM greenhouse gas emissions model. GHG greenhouse gas (including CO 2 2 4 GPS global positioning system. GVWR gross vehicle weight rating. HEV hybrid electric vehicle, including plug-in hybrid electric vehicles. HFET highway fuel economy test. HLDT heavy light-duty truck. HPLC high pressure liquid chromatography. IBR incorporated by reference. LA-92 Los Angeles 1992 driving schedule. MDPV medium-duty passenger vehicle. NIST National Institute for Standards and Technology. NMC nonmethane cutter. PDP positive-displacement pump. PHEV plug-in hybrid electric vehicle. PM particulate matter. RESS rechargeable energy storage system. ppm parts per million. SAE Society of Automotive Engineers. SC03 air conditioning driving schedule. SEA selective enforcement audit. SFTP Supplemental Federal Test Procedure. SI International System of Units. SSV subsonic venturi. UDDS urban dynamometer driving schedule. US06 aggressive driving schedule. U.S.C. United States Code. WWV NIST radio station call sign. (f) Densities of chemical species Table 6 of § 1066.1005—Densities of Chemical Species Symbol Quantity a b g/m 3 g/ft 3 ρ CH4 density of methane 666.905 18.8847 ρ CH3OH density of methanol 1332.02 37.7185 ρ C2H5OH C 1 957.559 27.1151 ρ C2H4O C 1 915.658 25.9285 ρ C3H8 density of propane 611.035 17.3026 ρ C3H7OH C 1 832.74 23.5806 ρ CO density of carbon monoxide 1164.41 32.9725 ρ CO2 density of carbon dioxide 1829.53 51.8064 ρ HC-gas effective density of hydrocarbon—gaseous fuel c (see 3) (see 3) ρ CH2O density of formaldehyde 1248.21 35.3455 ρ HC-liq effective density of hydrocarbon—liquid fuel d 576.816 16.3336 ρ NMHC-gas effective density of nonmethane hydrocarbon—gaseous fuel c (see 3) (see 3) ρ NMHC-liq effective density of nonmethane hydrocarbon—liquid fuel d 576.816 16.3336 ρ NMHCE-gas effective density of nonmethane equivalent hydrocarbon—gaseous fuel c (see 3) (see 3) ρ NMHCE-liq effective density of nonmethane equivalent hydrocarbon—liquid fuel d 576.816 16.3336 ρ NOx effective density of oxides of nitrogen e 1912.5 54.156 ρ N2O density of nitrous oxide 1829.66 51.8103 ρ THC-liq effective density of total hydrocarbon—liquid fuel d 576.816 16.3336 ρ THCE-liq effective density of total equivalent hydrocarbon—liquid fuel d 576.816 16.3336 a b 3 3 c ρ HCgas d e X 2 (g) Constants. Table 7 to Paragraph ( g Symbol Quantity mol/mol x Arair amount of argon in dry air 0.00934 x CO2air amount of carbon dioxide in dry air 0.000375 x N2air amount of nitrogen in dry air 0.78084 x O2air amount of oxygen in dry air 0.209445 (2) This part uses the following molar masses or effective molar masses of chemical species: Table 8 to Paragraph ( g Symbol Quantity g/mol − 3 − 1 M air molar mass of dry air 1 28.96559 M H2O molar mass of water 18.01528 1 (3) This part uses the following molar gas constant for ideal gases: Table 9 to Paragraph ( g Symbol Quantity J/(mol·K) 2 − 2 − 1 − 1 R molar gas constant 8.314472 (h) Prefixes. Table 10 to Paragraph ( h Symbol Quantity Value n nano 10 − 9 µ micro 10 − 6 m milli 10 − 3 c centi 10 − 2 k kilo 10 3 M mega 10 6 [79 FR 23823, Apr. 28, 2014, as amended at 80 FR 9124, Feb. 19, 2015; 81 FR 74215, Oct. 25, 2016; 86 FR 34585, June 29, 2021; 87 FR 64866, Oct. 26, 2022; 88 FR 4710, Jan. 24, 2023] § 1066.1010 Incorporation by reference. Certain material is incorporated by reference into this part with the approval of the Director of the Federal Register under 5 U.S.C. 552(a) and 1 CFR part 51. To enforce any edition other than that specified in this section, EPA must publish a document in the Federal Register www.epa.gov/dockets www.archives.gov/federal-register/cfr/ibr-locations.html [email protected] (a) National Institute of Standards and Technology (NIST), 100 Bureau Drive, Stop 1070, Gaithersburg, MD 20899-1070; (301) 975-6478; www.nist.gov (1) NIST Special Publication 811, 2008 Edition, Guide for the Use of the International System of Units (SI), Physics Laboratory, March 2008; IBR approved for §§ 1066.20(a); 1066.1005. (2) [Reserved] (b) SAE International, 400 Commonwealth Dr., Warrendale, PA 15096-0001; (877) 606-7323 (U.S. and Canada) or (724) 776-4970 (outside the U.S. and Canada); www.sae.org (1) SAE J1263 MAR2010, Road Load Measurement and Dynamometer Simulation Using Coastdown Techniques, Revised March 2010, (“SAE J1263”); IBR approved for §§ 1066.301(b); 1066.305(a); 1066.310(b). (2) SAE J1634 JUL2017, Battery Electric Vehicle Energy Consumption and Range Test Procedure, Revised July 2017, (“SAE J1634”); IBR approved for § 1066.501(a). (3) SAE J1711 FEB2023, Recommended Practice for Measuring the Exhaust Emissions and Fuel Economy of Hybrid-Electric Vehicles, Including Plug-In Hybrid Vehicles; Revised February 2023, (“SAE J1711”); IBR approved for §§ 1066.501(a); 1066.1001. (4) SAE J2263 DEC2008, Road Load Measurement Using Onboard Anemometry and Coastdown Techniques, Revised December 2008; IBR approved for §§ 1066.301(b); 1066.305; 1066.310(b). (5) SAE J2263 MAY2020, (R) Road Load Measurement Using Onboard Anemometry and Coastdown Techniques, Revised May 2020, (“SAE J2263”); IBR approved for §§ 1066.301(b); 1066.305; 1066.310(b). (6) SAE J2264 JAN2014, Chassis Dynamometer Simulation of Road Load Using Coastdown Techniques, Revised January 2014, (“SAE J2264”); IBR approved for § 1066.315. (7) SAE J2711 MAY2020, (R) Recommended Practice for Measuring Fuel Economy and Emissions of Hybrid-Electric and Conventional Heavy-Duty Vehicles, Revised May 2020, (“SAE J2711”); IBR approved for §§ 1066.501(a); 1066.1001. (8) SAE J2951 JAN2014, Drive Quality Evaluation for Chassis Dynamometer Testing, Revised January 2014, (“SAE J2951”); IBR approved for § 1066.425(j). (c) California Air Resources Board (California ARB). www.arb.ca.gov: (1) California 2026 and Subsequent Model Year Criteria Pollutant Exhaust Emission Standards and Test Procedures for Passenger Cars, Light-Duty Trucks, And Medium-Duty Vehicles (“California ARB's LMDV Test Procedures”); Adopted August 25, 2022; IBR approved for § 1066.801(c). (2) California Test Procedures for 2026 and Subsequent Model Year Zero-Emission Vehicles and Plug-In Hybrid Electric Vehicles, in the Passenger Car, Light-Duty Truck and Medium-Duty Vehicle Classes (“California ARB's PHEV Test Procedures”); Adopted August 25, 2022; IBR approved for § 1066.801(c). [88 FR 4711, Jan. 24, 2023, as amended at 89 FR 28215, Apr. 18, 2024]