Exhaust Gas Recirculation: Description and Operation

The function of the exhaust gas recirculation (EGR) system is monitored by the injection control unit. While the EGR valve is operated by vacuum, the vacuum supply is controlled by the EGR frequency valve, which is controlled by the injection control unit. This allows for a more precise control of when exhaust gasses are introduced into the combustion process, thus minimizing the affect on driveability and performance.
EGR was introduced mid year on all 5 cylinder cars sold in California.