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Measure emissions using the transient Low Load Cycle (LLC) as described in this section to determine whether engines meet the LLC emission standards in §1036.104. The LLC duty cycle is described in paragraph (d) of appendix B to this part. Procedures apply differently for testing certain kinds of engines and powertrains as follows:
(a) Test nonhybrid engines using the following procedures:
(1) Use the normalized speed and torque values for engine testing in the LLC duty cycle. Denormalize speed and torque values as described in 40 CFR 1065.512 and 1065.610 with the following additional requirements for testing at idle:
(i) Apply the accessory load at idle in paragraph (c) of this section using declared idle power as described in 40 CFR 1065.510(f)(6). Declared idle torque must be zero.
(ii) Apply CITT in addition to accessory load as described in this paragraph (a)(1)(ii). Set reference speed and torque values as described in 40 CFR 1065.610(d)(3)(vi) for all idle segments that are 200 s or shorter to represent the transmission operating in drive. For longer idle segments, set the reference speed and torque values to the warm-idle-in-drive values for the first three seconds and the last three seconds of the idle segment. For the points in between, set the reference speed and torque values to the warm-idle-in-neutral values to represent the transmission being manually shifted from drive to neutral shortly after the extended idle starts and back to drive shortly before it ends.
(2) Calculate and evaluate cycle-validation criteria as described in 40 CFR 1065.514, except as specified in paragraph (e) of this section.
(b) Test hybrid powertrains as described in §1036.510(b)(2), with the following exceptions:
(1) Replace Pcontrated with Prated, which is the peak rated power determined in §1036.520.
(2) Keep the transmission in drive for all idle segments 200 seconds or less. For idle segments more than 200 seconds, leave the transmission in drive for the first 3 seconds of the idle segment, then immediately place the transmission in park or neutral, and shift the transmission into drive again 3 seconds before the end of the idle segment. The end of the idle segment occurs at the first nonzero vehicle speed setpoint.
(3) For hybrid engines, you may request to change the GEM-generated engine reference torque at idle to better represent curb idle transmission torque (CITT).
(4) Adjust procedures in this section as described in §1036.510(d) and (e) for plug-in hybrid powertrains to determine criteria pollutant and greenhouse gas emissions, replacing “SET” with “LLC”. Note that the LLC is therefore the preconditioning duty cycle for plug-in hybrid powertrains.
(5) Calculate and evaluate cycle-validation criteria as specified in §1036.545.
(c) Include vehicle accessory loading as follows:
(1) Apply a vehicle accessory load for each idle point in the cycle using the power values in the following table:
| Primary intended service class | Power representing accessory load (kW) |
|---|---|
| Light HDE | 1.5 |
| Medium HDE | 2.5 |
| Heavy HDE | 3.5 |
(2) For nonhybrid engine testing, apply vehicle accessory loads in addition to any applicable CITT.
(3) Additional provisions related to vehicle accessory load apply for engines with stop-start technology and hybrid powertrains where the accessory load is applied to the engine shaft. Account for the loss of mechanical work due to the lack of any idle accessory load during engine-off conditions by determining the total loss of mechanical work from idle accessory load during all engine-off intervals over the entire test interval and distributing that work over the engine-on portion of the entire test interval based on a calculated average power. You may determine the engine-off time by running practice cycles or through engineering analysis.
(d) Except as specified in paragraph (b)(4) of this section for plug-in hybrid powertrains, the test sequence consists of preconditioning the engine by running one or two FTPs with each FTP followed by (20 ± 1) minutes with no engine operation and a hot start run through the LLC. You may start any preconditioning FTP with a hot engine. Perform testing as described in 40 CFR 1065.530 for a test interval that includes engine starting. Calculate the total emission mass of each constituent, m, over the test interval as described in 40 CFR 1065.650. For nonhybrid engines, calculate the total work, W, over the test interval as described in 40 CFR 1065.650(d). For hybrid powertrains, calculate total positive work over the test interval using system power, Psys. Determine Psys using §1036.520(f). For powertrains with automatic transmissions, account for and include the work produced by the engine from the CITT load.
(e) For testing spark-ignition gaseous-fueled engines with fuel delivery at a single point in the intake manifold, you may apply the alternative cycle-validation criteria for the LLC in the following table:
| Parameter | Speed | Torque | Power |
| Slope, a1 | 0.800 ≤ a1 ≤ 1.030 | 0.800 ≤ a1 ≤ 1.030. | |
|
Absolute value of intercept, |
a0
|
Standard error of the estimate, SEE | ≤15% of maximum mapped power. | ||
| Coefficient of determination, r2 | ≥0.650 | ≥0.650. | |
| a Cycle-validation criteria apply as specified in 40 CFR 1065.514 unless otherwise specified. | |||
[88 FR 4487, Jan. 24, 2023; 89 FR 29746, Apr. 22, 2024]