Chapter 11-4 Emissions Tests Emissions Tests continued In this test, the inspection uses an opacity meter or “smoke meter” to measure the smoke from the vehicle’s exhaust pipe. The darker the smoke, the more the vehicle is polluting and the higher its opacity reading will be. The inspector first secures the vehicle safely (so it cannot move) and tests to ensure that its engine governor is functioning properly. The inspector presses on the throttle to bring the engine up to it maximum governed revolutions per minute (RPM) several times—first to remove loose soot from the exhaust pipe, then to measure the opacity of the vehicle’s emissions. Reading from the final three acceleration “snaps” are averaged. The final average is compared to the emission standard for the model year and type of vehicle. Newer vehicles have more sophisticated emission controls, and must meet stricter standards. 10/08 11:17