Fuel consumption at idle.
Fuel consumption at idle. Determine fuel-consumption rates for engines certified for installation in vocational vehicles for each engine configuration over a series of engine-idle operating points consisting of pairs of speed and torque points as described in this paragraph (c). You may use shared data across engine configurations, consistent with good engineering judgment. Perform measurements as follows:
(1) Determine the required engine-idle operating points as follows:
(i) Select the following two speed setpoints:
(A) Engines with an adjustable warm idle speed setpoint: Minimum warm idle speed, fnidlemin, and the maximum warm idle speed, fnidlemax.
(B) Engines without an adjustable warm idle speed setpoint: Warm idle speed (with zero torque on the primary output shaft), fnidle, and 1.15 times fnidle.
(ii) Select the following two torque setpoints at each of the selected speed setpoints: 0 and 100 N·m.
(iii) You may run these four engine-idle operating points in any order.
(2) Control speed and torque as follows:
(i) Engines with an adjustable warm idle speed setpoint. For the warm-up in paragraph (c)(3) of this section and the transition in paragraph (c)(4) of this section control both speed and torque. At any time prior to reaching the next engine-idle operating point, set the engine's adjustable warm idle speed setpoint to the speed setpoint of the next engine-idle operating point in the sequence. This may be done before or during the warm-up or during the transition. Near the end of the transition period control speed and torque as described in paragraph (b)(3)(i) of this section. Once the transition is complete; set the operator demand to minimum to allow the engine governor to control speed; and control torque with the dynamometer as described in paragraph (b)(3) of this section.
(ii) Engines without an adjustable warm idle speed setpoint. Control speed and torque with operator demand and the dynamometer for the engine-idle operating points at the higher speed setpoint as described in paragraph (b)(3) of this section. Both the speed and torque tolerances apply for these points because they are not near the engine's operating boundary and are achievable. Control speed and torque for the engine-idle operating points at the lower speed setpoint as described in paragraph (c)(2)(i) of this section except for setting the engine's adjustable warm idle speed setpoint.
(3) Warm-up the engine as described in 40 CFR 1065.510(b)(2).
(4) After concluding the warm-up procedure, linearly ramp the speed and torque setpoints over 20 seconds to operate the engine at the next engine-idle operating point from paragraph (c)(1) of this section.
(5) Operate the engine at the engine-idle operating point for (180 ±1) seconds, and then start the test interval and record measurements using one of the following methods. You must also measure and report NOX emissions over each test interval as described in paragraph (a)(2) of this section. If you use redundant systems for the determination of fuel consumption, for example combining measurements of dilute and raw emissions when generating your map, follow the requirements of 40 CFR 1065.201(d).
(i) Indirect measurement of fuel flow. Record speed and torque and measure emissions and other inputs needed to run the chemical balance in 40 CFR 1065.655(c) for a (600 ±1) second test interval; determine the corresponding mean values for the test interval. We will use an average of indirect measurement of fuel flow with dilute sampling and direct sampling. For dilute sampling of emissions, measure background according to the provisions described in 40 CFR 1065.140, but read the background as described in paragraph (c)(7)(i) of this section. If you use batch sampling to measure background emissions, you may sample periodically into the bag over the course of multiple test intervals and read them as allowed in paragraph (b)(7)(i) of this section. If you use this paragraph (c)(5)(i), you must apply the same background readings to correct emissions from each of the applicable test intervals. Note that the minimum dilution ratio requirements for PM sampling in 40 CFR 1065.140(e)(2) do not apply. We recommend minimizing the CVS flow rate to minimize errors due to background correction consistent with good engineering judgment and operational constraints such as minimum flow rate for good mixing.
(ii) Direct measurement of fuel flow. Record speed and torque and measure fuel consumption with a fuel flow meter for a (600 ±1) second test interval; determine the corresponding mean values for the test interval.
(6) After completing the test interval described in paragraph (c)(5) of this section, repeat the steps in paragraphs (c)(3) through (5) of this section for all the remaining engine-idle operating points. After completing the test interval on the last engine-idle operating point, the fuel-consumption-at-idle sequence is complete.
(7) The following provisions apply for interruptions in the fuel-consumption-at-idle sequence in a way that is intended to produce results equivalent to running the sequence without interruption:
(i) You may pause the fuel-consumption-at-idle sequence after each test interval to calibrate emission-measurement instrumentation and to read and evacuate background bag samples collected over the course of a single test interval. This paragraph (c)(7)(i) allows you to shut-down the engine or to spend more time at the speed/torque idle setpoint after completing the test interval before transitioning to the step in paragraph (c)(3) of this section.
(ii) If an infrequent regeneration event occurs, interrupt the fuel-consumption-at-idle sequence and allow the regeneration event to finish. You may continue to operate at the engine-idle operating point where the event began or, using good engineering judgment, you may transition to another operating condition to reduce the regeneration event duration. If the event occurs during a test interval, void that test interval. Once the regeneration event is finished, restart the fuel-consumption-at-idle sequence by repeating the steps in paragraphs (c)(3) through (5) of this section for all the remaining engine-idle operating points.
(iii) You may interrupt the fuel-consumption-at-idle sequence after any of the test intervals. Restart the fuel-consumption-at-idle sequence by repeating the steps in paragraphs (c)(3) through (5) of this section for all the remaining engine-idle operating points.
(iv) If the fuel-consumption-at-idle sequence is interrupted due to test equipment or engine malfunction, correct the malfunction and restart the fuel-consumption-at-idle sequence by repeating the steps in paragraphs (c)(3) through (5) of this section for all the remaining engine-idle operating points. If the malfunction occurred during a test interval, void that test interval.
(v) If any idle test intervals are voided, repeat the steps in paragraphs (c)(3) through (5) of this section for each of the voided engine-idle operating points.
(8) Correct the measured or calculated mean fuel mass flow rate, m fuel at each of the engine-idle operating points to account for mass-specific net energy content as described in paragraph (b)(13) of this section.
(d) Steady-state fuel maps used for cycle-average fuel mapping of the cruise cycles. Determine fuel-consumption rates for each engine configuration over a series of steady-state engine operating points near idle as described in this paragraph (d). You may use shared data across an engine platform to the extent that the fuel-consumption rates remain valid.
(1) Perform steady-state fuel mapping as described in paragraph (b) of this section with the following exceptions:
(i) All the required steady-state engine operating points as described in paragraph (b)(1)(i) of this section are optional.
(ii) Select speed setpoints to cover the range of idle speeds expected as follows:
(A) The minimum number of speed setpoints is two.
(B) For engines with an adjustable warm idle speed setpoint, the minimum speed setpoint must be equal to the minimum warm idle speed, fnidlemin, and the maximum speed setpoint must be equal to or greater than the maximum warm idle speed, fnidlemax. The minimum speed setpoint for engines without an adjustable warm idle speed setpoint, must be equal to the warm idle speed (with zero torque on the primary output shaft), fnidle, and the maximum speed setpoint must be equal to or greater than 1.15 times the warm idle speed, fnidle.
(iii) Select torque setpoints at each speed setpoint to cover the range of idle torques expected as follows:
(A) The minimum number of torque setpoints at each speed setpoint is three. Note that you must meet the minimum torque spacing requirements described in paragraph (b)(1)(ii) of this section.
(B) The minimum torque setpoint at each speed setpoint is zero.
(C) The maximum torque setpoint at each speed setpoint must be greater than or equal to the estimated maximum torque at warm idle (in-drive) conditions, Tidlemaxest, using the following equation. For engines with an adjustable warm idle speed setpoint, evaluate Tidlemaxest at the maximum warm idle speed, fnidlemax. For engines without an adjustable warm idle speed setpoint, use the warm idle speed (with zero torque on the primary output shaft), fnidle.
(2) [Reserved]
(3) Add the points measured in paragraph (d)(1) of this section.