EGR Electronic Vacuum Regulator Solenoid: Description and Operation

EGR Control Solenoid:

PURPOSE
Controls vacuum supply to EGR valve, thereby controlling EGR operation.

LOCATION
On right side of intake manifold, near the EGR valve.

OPERATION
To regulate EGR flow, an ECM controlled Electronic Vacuum Regulator Valve (EVRV) solenoid is used in the vacuum line between EGR valve and vacuum source. The ECM uses information from these sensors to regulate the solenoid:

- Coolant temperature sensor
- Throttle position sensor
- Distributor rpm signal

The EVRV solenoid is controlled with "pulse width modulation." This means the ECM 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.

This type of system is sometimes referred to as having a "duty cycle," where duty cycle corresponds to pulse width.