EGR System - Gasoline: 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, altitude, temperature, throttle angle and engine speed.

Typical systems consist of an EGR valve, carburetor EGR port, vacuum tank, check valve, and a Ported Vacuum Switch (PVS) and/or a Temperature Vacuum Switch (TVS).

There are 4 basic types of EGR valves. They are Integral Backpressure Valve, Ported EGR Valve, Electronic EGR Valve and Valve and Transducer Assembly EGR Valve, which is a modified Ported EGR Valve.

The Backpressure Variable Transducer (BVT) system is used on some models. This system combines a ported EGR valve with a Backpressure Variable Transducer (BVT) to control NOx emissions. Typical components included in this system are EGR Valve, PVS or TVS and carburetor EGR port or vacuum tank vacuum source.

Models with Electronic Engine Control (EEC) systems use an electronic EGR system with an electronic EGR valve with a EGR-Valve Position (EVP) 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. System also has EGR Solenoid Vacuum Valve Assembly.

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