Exhaust Gas Recirculation: Description and Operation
Description and OperationThe EGR system is comprised of three main components, the EGR Valve, the Pressure Feedback Transducer, and the Electronic Vacuum Regulator.
The Pressure Feedback Electronic (PFE) EGR valve is a conventional ported EGR valve with a backpressure sensing tube attached to it. The valve is used in conjunction with a pressure transducer (9J460) which supplies pressure feedback to the EEC-IV processor. The EGR flow rate is proportional to the pressure drop across a remotely mounted sharp edged orifice.
The Pressure Feedback Electronic (PFE) EGR transducer convents a varying exhaust pressure signal into a proportional analog voltage which is digitized by the EEC-IV processor. The EEC-IV processor uses the signal received from the PFE transducer to compute the optimum EGR flow.
The Electronic Vacuum Regulator (EVR) is an electromagnetic device which controls vacuum output to the EGR valve. The EVR replaces the EGR Solenoid Vacuum Vent Valve Assembly (9D474). An electric current in the coil induces a magnetic field in the armature. The magnetic field pushes against a spring loaded disc increasing the vacuum level. The vacuum source is either manifold or port vacuum. As the current is increased an increased vacuum signal goes to the EGR.