40 CFR § 1037.510 - Duty-cycle exhaust testing.

§ 1037.510 Duty-cycle exhaust testing.

This section applies for powertrain testing, cycle-average engine fuel mapping, certain off-cycle testing under § 1037.610, and the advanced-technology provisions of § 1037.615.

(a) Measure emissions by testing the vehicle on a chassis dynamometer or the powertrain on a powertrain dynamometer with the applicable duty cycles. Each duty cycle consists of a series of speed commands over time - variable speeds for the transient test and constant speeds for the highway cruise tests. None of these cycles include vehicle starting or warmup.

(1) Perform testing for Phase 1 vehicles as follows to generate credits or adjustment factors for off-cycle or advanced technologies:

(i) Transient cycle. The transient cycle is specified in Appendix I of this part. Warm up the vehicle. Start the duty cycle within 30 seconds after concluding the preconditioning procedure. Start sampling emissions at the start of the duty cycle.

(ii) Cruise cycle. For the 55 mi/hr and 65 mi/hr highway cruise cycles, warm up the vehicle at the test speed, then sample emissions for 300 seconds while maintaining vehicle speed within ±1.0 mi/hr of the speed setpoint; this speed tolerance applies instead of the approach specified in 40 CFR 1066.425(b)(1) and (2).

(2) Perform cycle-average engine fuel mapping as described in 40 CFR 1036.540. For powertrain testing under § 1037.550 or § 1037.555, perform testing as described in this paragraph (a)(2) to generate GEM inputs for each simulated vehicle configuration, and test runs representing different idle conditions. Perform testing as follows:

(i) Transient cycle. The transient cycle is specified in appendix I of this part.

(ii) Highway cruise cycles. The grade portion of the route corresponding to the 55 mi/hr and 65 mi/hr highway cruise cycles is specified in appendix IV of this part. Maintain vehicle speed between −1.0 mi/hr and 3.0 mi/hr of the speed setpoint; this speed tolerance applies instead of the approach specified in 40 CFR 1066.425(b)(1) and (2).

(iii) Drive idle. Perform testing at a loaded idle condition for Phase 2 vocational vehicles. For engines with an adjustable warm idle speed setpoint, test at the minimum warm idle speed and the maximum warm idle speed; otherwise simply test at the engine's warm idle speed. Warm up the powertrain using the vehicle settings for the Test 1 vehicle configuration as defined in Table 2 or 3 of 40 CFR 1036.540 by operating it at 65 mi/hr for 600 seconds. Linearly ramp the powertrain down to zero vehicle speed in 20 seconds. Set the engine to operate at idle speed for 90 seconds, with the brake applied and the transmission in drive (or clutch depressed for manual transmission), and sample emissions to determine mean emission values (in g/s) over the last 30 seconds of idling.

(iv) Parked idle. Perform testing at an unloaded idle condition for Phase 2 vocational vehicles. For engines with an adjustable warm idle speed setpoint, test at the minimum warm idle speed and the maximum warm idle speed; otherwise simply test at the engine's warm idle speed. Warm up the powertrain using the vehicle settings for the Test 1 vehicle configuration by operating it at 65 mi/hr for 600 seconds. Linearly ramp the powertrain down to zero vehicle speed in 20 seconds. Set the engine to operate at idle speed for 780 seconds, with the transmission in park (or the transmission in neutral with the parking brake applied for manual transmissions), and sample emissions to determine mean emission values (in g/s) over the last 600 seconds of idling.

(3) Where applicable, perform testing on a chassis dynamometer as follows:

(i) Transient cycle. The transient cycle is specified in Appendix I of this part. Warm up the vehicle by operating over one transient cycle. Within 60 seconds after concluding the warm up cycle, start emission sampling and operate the vehicle over the duty cycle.

(ii) Highway cruise cycle. The grade portion of the route corresponding to the 55 mi/hr and 65 mi/hr highway cruise cycles is specified in Appendix IV of this part. Warm up the vehicle by operating it at the appropriate speed setpoint over the duty cycle. Within 60 seconds after concluding the preconditioning cycle, start emission sampling and operate the vehicle over the duty cycle, maintaining vehicle speed within ±1.0 mi/hr of the speed setpoint; this speed tolerance applies instead of the approach specified in 40 CFR 1066.425(b)(1) and (2).

(b) Calculate the official emission result from the following equation:

Where:
eCO2comp = total composite mass of CO2 emissions in g/ton-mile, rounded to the nearest whole number for vocational vehicles and to the first decimal place for tractors.
PL = the standard payload, in tons, as specified in § 1037.705.
vmoving = mean composite weighted driven vehicle speed, excluding idle operation, as shown in table 1 to this section for Phase 2 vocational vehicles. For other vehicles, let vmoving = 1.
w[cycle] = weighting factor for the appropriate test cycle, as shown in table 1 to this section.
m[cycle] = CO2 mass emissions over each test cycle (other than idle).
D[cycle] = the total driving distance for the indicated duty cycle. Use 2.842 miles for the transient cycle, and use 13.429 miles for both of the highway cruise cycles.
m
[cycle]-idle = CO2 emission rate at idle.
Example:

Class 7 vocational vehicle meeting the Phase 2 standards based on the Regional duty cycle.

PL = 5.6 tons
vmoving = 38.41 mi/hr
wtransient = 20% = 0.20
wdrive-idle = 0% = 0
wparked-idle = 25% = 0.25
w55 = 24% = 0.24
w65 = 56% = 0.56
mtransient = 4083 g
m55 = 13834 g
m65 = 17018 g
Dtransient = 2.8449 miles
D55 = 13.429 miles
D65 = 13.429 miles
m
drive-idle = 4188 g/hr
m
parked-idle = 3709 g/hr

(c) Weighting factors apply for each type of vehicle and for each duty cycle as follows:

(1) GEM applies weighting factors for specific types of tractors as shown in Table 1 of this section.

(2) GEM applies weighting factors for vocational vehicles as shown in Table 1 of this section. Modeling for Phase 2 vocational vehicles depends on characterizing vehicles by duty cycle to apply proper weighting factors and average speed values. Select either Urban, Regional, or Multi-Purpose as the most appropriate duty cycle for modeling emission results with each vehicle configuration, as specified in §§ 1037.140 and 1037.150.

(3) Table 1 follows:

Table 1 of § 1037.510 - Weighting Factors for Duty Cycles

Distance-weighted Time-weighted a Average
speed
during
non-idle
cycles
(mi/hr) b
Transient
(%)
55 mi/hr
cruise
(%)
65 mi/hr
cruise
(%)
Drive
idle
(%)
Parked
idle
(%)
Non-idle
(%)
Day Cabs 19 17 64
Sleeper Cabs 5 9 86
Heavy-haul tractors 19 17 64
Vocational - Regional 20 24 56 0 25 75 38.41
Vocational - Multi-Purpose (2b-7) 54 29 17 17 25 58 23.18
Vocational - Multi-Purpose (8) 54 23 23 17 25 58 23.27
Vocational - Urban (2b-7) 92 8 0 15 25 60 16.25
Vocational - Urban (8) 90 10 0 15 25 60 16.51
Vocational with conventional powertrain (Phase 1 only) 42 21 37
Vocational Hybrid Vehicles (Phase 1 only) 75 9 16

a Note that these drive idle and non-idle weighting factors do not reflect additional drive idle that occurs during the transient cycle. The transient cycle does not include any parked idle.

b These values apply even for vehicles not following the specified speed traces.

(d) For transient testing, compare actual second-by-second vehicle speed with the speed specified in the test cycle and ensure any differences are consistent with the criteria as specified in 40 CFR 1066.425(b) and (c). If the speeds do not conform to these criteria, the test is not valid and must be repeated.

(e) Run test cycles as specified in 40 CFR part 1066. For testing vehicles equipped with cruise control over the highway cruise cycles, you may use the vehicle's cruise control to control the vehicle speed. For vehicles equipped with adjustable vehicle speed limiters, test the vehicle with the vehicle speed limiter at its highest setting.

(f) For Phase 1, test the vehicle using its adjusted loaded vehicle weight, unless we determine this would be unrepresentative of in-use operation as specified in 40 CFR 1065.10(c)(1).

(g) For hybrid vehicles, correct for the net energy change of the energy storage device as described in 40 CFR 1066.501.

[81 FR 74048, Oct. 25, 2016, as amended at 86 FR 34465, June 29, 2021; 87 FR 45264, July 28, 2022]