EGR System: Description

The Exhaust Gas Recirculation (EGR) system is designed to reintroduce small amounts of exhaust gas into the combustion cycle, thus reducing the amounts of NOx emissions. The amount of exhaust gas recycled and the timing of the cycle are controlled by such factors as engine vacuum, exhaust system backpressure, temperature, throttle angle and engine speed.

Typical systems consist of an EGR valve, a spacer plate on which the valve is mounted, a vacuum amplifier, a check valve, and a ported vacuum switch (PVS) or a temperature vacuum switch (TVS).

An EGR Vacuum Regulator Control system is used on some models. This system combines a ported EGR valve with with a backpressure variable transducer (BVT) to control NOx emissions.

Models with Electronic Engine Control (EEC) systems use an electronic EGR system with an electronic sonic EGR valve and a EGR valve position sensor. In addition, these vehicles use an exhaust cooler which uses coolant to reduce the temperature of exhaust flowing through the EGR valve and into the engine.

Some selected 2.0L and 2.3L engines use a EGR valve and transducer assembly which consists of an external entry ported EGR valve and a pressure tap to provide a backpressure signal to the remote transducer. This system operates the same as the Integral Backpressure Transducer valve system. Function checks are the same as that system.