Exhaust Gas Recirculation: Description and Operation

EGR System Function:

EGR And Vacuum System Diagram:

PURPOSE
This system cuts and controls vacuum applied to EGR valve and canister to suit engine operating conditions.

OPERATION
This cut-and-control operation is accomplished through the ECM and the EGR & canister control solenoid valve. When the ECM detects any of the following conditions, current flows through the solenoid valve. This causes the port vacuum to be discharged into the atmosphere. The EGR valve and canister remain closed.
1. Low engine coolant temperature
2. Engine starting
3. High-speed engine operation
4. Engine idling
5. Excessively high engine coolant temperature
6. Mass air flow sensor malfunction