(a)Sequence steps. Figure C94-1 shows the steps encountered as the test vehicle undergoes the procedures subsequently described, to determine conformity with the standards set forth.
(b)Driving schedule. The Urban Dynamometer Driving Schedule (UDDS) test procedure (see § 86.115 and appendix I to this part) is used for vehicle preconditioning and testing.
(c)Ambient temperature level.
(1) Ambient temperature levels encountered by the test vehicle shall average 20 °F±5 °F (−7 °C±2.8 °C) and shall not be less than 10 °F (−14 °C) nor more than 30 °F (−1 °C) during vehicle preconditioning, except for preconditioning performed in accordance with § 86.232(a)(7), and during all emission testing.
(2) The ambient temperature reported shall be a simple average of the test cell temperatures measured at constant intervals no more than one minute apart. Before the driving cycle may begin, the test cell temperature shall be 20 °F±3 °F (−7 °C±1.7 °C) when measured in accordance with paragraph (e)(2) of this section. The temperature may not exceed 25 °F (−4 °C) or fall below 15 °F (−9 °C) for more than three consecutive minutes during the test.
(d)Vehicle positioning. The vehicle shall be approximately level during all phases of the test sequence to prevent abnormal fuel distribution.
(e)Engine compartment cooling.
(1) Fixed speed air cooling of the engine compartment with the compartment cover open shall be utilized during testing that is conducted by the Administrator and, optionally for certification testing, by the manufacturer. If a separate movable fan is used, it shall be squarely positioned within 12 inches (30.5 centimeters) of the front of vehicles with front engine compartments. In the case of vehicles with rear engine compartments (or if special designs make the normal front engine positioning impractical), the cooling fan shall be placed in a position to provide sufficient air to maintain vehicle cooling. The fan capacity shall normally not exceed 5,300 cfm (2.50 cubic meters per second). If, however, the manufacturer showed (as provided in § 86.135-94(b)) that additional cooling is necessary, the fan capacity may be increased or additional fans used if approved in advance by the Administrator. The cooling air temperature shall be measured at the inlet to the fan.
(2) In lieu of using a separate fan, an air handling system that is integral with the test cell may be used provided comparable air movement is obtained. The cooling air temperature shall be measured in the center of a vertical plane that is located approximately 2 feet in front of the vehicle.
(3) The manufacturer may use, for certification and fuel economy testing, alternative engine compartment cooling fans or systems, including those which provide a variable air flow, if the manufacturer has determined that comparable results are obtained. For 2009 and later model year vehicles, manufacturers may perform the test with the engine compartment closed, e.g. to provide adequate air flow to air flow to an intercooler through a factory installed hood scoop, if needed to provide a representative test. For 2009 and later model year vehicles, the Administrator may conduct certification, fuel economy and in-use testing using the additional cooling set-up approved for a specific vehicle.
(f)Heater and defroster usage. The heater and defroster may be used at any temperature and fan settings.
[57 FR 31916, July 17, 1992, as amended at 74 FR 61548, Nov. 25, 2009]
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