Exhaust Gas Recirculation: Description and Operation

The exhaust gas recirculation system consists of a valve, a vacuum regulator valve, a tube and a differential pressure sensor.
The exhaust gas recirculation system recycles measured quantities of exhaust gas back through the engine where they mix with incoming fuel/air charge.
The powertrain control module controls the vacuum regulator valve with grounding pulses. This regulates the amount and duration of the vacuum signal supplied to the exhaust gas recirculation valve and thus the valve lift and opening time are controlled.
The differential pressure sensor provides the powertrain control module with data relating to the exact amount of exhaust gas being recirculated by measuring the differential pressure across a calibrated orifice in the supply hose. Thus, closed loop control is achieved.