Exhaust Gas Recirculation: Description and Operation

OPERATION
Exhaust Gas Recirculation (EGR) is regulated by a solenoid-type vacuum regulator device which is controlled by the Powertrain Control Module (PCM), based on return signals from various engine components, and the pressure transducer/sensor. Circuit power is supplied through the PCM power relay when circuit ground is provided internally by the PCM.

Typical DPFE EGR System:

The DPFE system is a subsonic closed loop EGR system that controls Exhaust Gas Recirculation by monitoring the exhaust pressure drop across a remotely located sharp-edged orifice, and by monitoring exhaust system back pressure. The system uses a pressure transducer/sensor to send a returning analog voltage signal to the PCM. The PCM controls the varying pressure by modulating the vacuum output of the EGR Vacuum Regulator (EVR) Solenoid.

NOTE: Other vacuum related components may be incorporated into the EGR system, depending on vehicle model and calibration.