Exhaust Gas Recirculation: Description and Operation: Overview

The EGR system is a back pressure type and is controlled by a back pressure transducer and the logic module. The logic module controls vacuum through the EGR solenoid, turning the circuit on or off according to operating conditions. The back pressure transducer measures the amount of exhaust back pressure on the exhaust side of the EGR valve. The logic module prevents EGR operation by turning the EGR solenoid off at idle, at wide open throttle or when engine temperature is below 70° F. The back pressure transducer vents the vacuum circuit of the EGR valve to the atmosphere whenever less than 0 psi is sensed at the exhaust side of the EGR valve.