Exhaust Gas Recirculation (EGR) Systems

EVRV Circuit (Typical):

PURPOSE
To provide electrical control of the Exhaust Gas Recirculation (EGR) valve.

OPERATION
To regulate EGR flow, a control module controlled Electronic Vacuum Regulator Valve (EVRV) solenoid is used in the vacuum line. The control module uses information from the following sensors to regulate the solenoid:

- Engine Coolant Temperature Sensor (ECT).
- Throttle Position Sensor (TP).
- Park/Neutral (P/N) switch.
- Distributor (RPM signal).

The EGR vacuum control has an EVRV solenoid that uses Pulse Width Modulation (PWM). This means the control module turns the solenoid ON and OFF many times a second and varies the amount of ON time (pulse width) to vary the amount of EGR.