Fuel Injected Models

1982-85 Models
This system is a back pressure type and is controlled in two ways. The vacuum through the EGR solenoid is controlled by a logic module which cycles the vacuum circuit ``On'' or ``Off.'' The amount of exhaust back pressure is measured by the back pressure transducer, located on the exhaust side of the EGR valve. EGR operation is discontinued by the logic module by turning the EGR solenoid ``Off'' at idle, wide open throttle or when engine temperature is below 70° F. The EGR signal is adjusted by the back pressure transducer to provide programmed amounts of exhaust gas recirculation under all other conditions.
The EGR solenoid is also operated by the logic module and when engine temperature falls below 70° F, the solenoid is energized by the logic module by grounding it. This closes the solenoid and prevents ported vacuum from reaching the EGR valve. When engine temperature exceeds 70° F, the logic module bypasses the ground signal, thereby de-energizing the solenoid and allowing ported vacuum from the throttle body to pass through the EGR valve. At idle and wide open throttle, the solenoid is energized, which prevents EGR operation.