CFR > Title 40 - Protection of Environment > CHAPTER I—ENVIRONMENTAL PROTECTION AGENCY > SUBCHAPTER C—AIR PROGRAMS (Parts 50–99) > PART 86—CONTROL OF EMISSIONS FROM NEW AND IN-USE HIGHWAY VEHICLES AND ENGINES > SUBPART M—Evaporative Emission Test Procedures for New Gasoline-Fueled, Natural Gas-Fueled, Liquefied Petroleum Gas-Fueled and Methanol-Fueled Heavy-Duty Vehicles (§86.1201-90 to §86. > 86.1237-85—Dynamometer runs.

86.1237-85—Dynamometer runs.

(a) The vehicle shall be either driven or pushed onto the dynamometer; however, if driven, the period of engine operation between the end of the diurnal loss test and beginning of the hot soak preparation run shall not exceed 3 minutes, and the vehicle shall be driven at minimum throttle. The dynamometer run shall follow the diurnal heat build by not more than one hour. The vehicle shall be stored prior to dynamometer operation in such a manner that it is not exposed to precipitation (e.g., rain or dew).
(b) The following steps shall be taken for the dynamometer run:
(1) Place drive wheels of vehicle on the dynamometer.
(2) Position the cooling fan(s).
(3) Attach an exhaust tube to the vehicle tailpipe(s).
(4) Start the engine.
(5) Turn on the cooling fan(s).
(6) Operate the vehicle according to the dynamometer driving schedule ( § 86.1215-85 ).
(7) At the end of the last deceleration, disconnect the exhaust tube from the vehicle tailpipe(s) and drive vehicle from the dynamometer.