Exhaust Gas Recirculation: Description and Operation

DIFFERENTIAL PRESSURE FEEDBACK EXHAUST GAS RECIRCULATION (DPFE)

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

Typical PFE 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 EEC Module. The EEC Module 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.


DPFE TRANSDUCER/SENSOR

Differential Pressure Feedback Electronic (DPFE) EGR Sensor:

The Differential Pressure Feedback EGR Transducer/Sensor is a ceramic capacitive-type pressure sensor. Exhaust pressure or vacuum is converted into a proportional analog voltage signal, which is digitized by the EEC-IV Processor. The EEC processor uses the signal received from the DPFE Transducer to compute optimum EGR flow rate, as well as to monitor EGR flow.


DPFE VALVE

Typical EGR Valve:

The Differential Pressure Feedback EGR Valve is a conventional ported EGR Valve. The service replacement does not include the pick up tube/plug. If the valve is to be replaced, the original pick up tube/plug should be used with the new service valve.