EGR Valve: Description and Operation

The system, reduces the formation of nitrous oxides produced during the combustion process, by diluting the fresh intake air fuel mixture with a metered amount of exhaust gases.

The amount of metered exhaust gases and the timing of the cycle is controlled by various factors such as engine speed, altitude, engine vacuum, exhaust system backpressure, coolant temperature and throttle valve opening. An EGR valve was only used on the carbureted version of the Tracer for this year.