EGR Valve: Description and Operation

Exhaust Gas Recirculation (EGR):

PURPOSE
The Exhaust Gas Recirculation (EGR) valve is the main component of the EGR system. The EGR valve feeds small amounts of exhaust gas back into the combustion chamber by opening to allow that exhaust gas flow into the intake manifold. The exhaust gas then moves with the air / fuel mixture into the combustion chamber. If too much exhaust gas enters, combustion will not occur. For this reason, very little exhaust gas is allowed to pass through the valve, especially at idle. The EGR valve is usually open during warm engine operation and when the vehicle is above idle speed. The amount of exhaust gas recirculated is controlled by the EGR vacuum control solenoid.

OPERATION
The integrated electronic EGR valve functions like a port valve with a remote vacuum regulator, except the regulator and pintle position sensor are sealed in a black plastic cover. The regulator and position sensor are not serviceable. There is a serviceable filter, that provides clean fresh air to the regulator along side the vacuum tube.

Results Of Incorrect Operation
With too much EGR flow at idle, cruise, or cold operation, any of the following conditions may occur:
^ Engine stalls after cold start
^ Engine stalls at idle after deceleration
^ Car surges during cruise
^ Rough idle

Too little or no EGR flow allows combustion temperatures to get too high. This could cause:
^ Spark knock (detonation)
^ Engine overheating
^ Emission test failure