Exhaust Gas Recirculation: Description and Operation

EGR System:

PURPOSE
The EGR system aims at reduction of NOx by lowering combustion chamber temperature through recirculation of a part of exhaust gas into cylinders via the collector chamber. The EGR system consists of the following components:
^ Back pressure transducer
^ EGR valve
^ EGR control solenoid
^ EGR temperature sensor (California only)

OPERATION
The Engine Control Module signals the EGR solenoid to switch from ported vacuum to atmospheric pressure, thereby opening and closing the EGR valve. The EGR valve opens in response to engine driving conditions and provides a portion of exhaust gas to the cylinders through the intake manifold. The valve is further controlled by means of a backpressure transducer. The transducer limits vacuum to the valve based on sensed exhaust backpressure.