Exhaust Gas Recirculation: Description and Operation

EGR System Chart:

PURPOSE AND OPERATION
A system is provided which precisely cuts and controls port vacuum applied to the Exhaust Gas Recirculation (EGR) valve to suit engine operating conditions. This cut-and-control operation is accomplished through the Engine Control Module (ECM). When the ECM detects any of the following conditions, current flows through the solenoid valve in the EGR control vacuum line. This causes the port vacuum to be discharged into the atmosphere so that the EGR valve remains closed.

^ Low engine coolant temperature

^ Engine starting

^ High-speed engine operation

^ Engine idling

^ Excessively high engine coolant temperature