Division 4.2.5.3.2.2 Test procedure

The engine speed shall be gradually increased from idle to the target engine speed, not exceeding a tolerance band of ± 3 % of the target engine speed, and held constant. Then the throttle control shall be rapidly released and the engine speed shall return to idle. The sound level shall be measured during a period of operation consisting of maintaining constant engine speed of 1 second and throughout the entire deceleration period. The maximum sound level meter reading during this period of operation, mathematically rounded to the first decimal place, shall be taken as the test value.