Silhouette V6-191 3.1L VIN D TBI (1995)
EGR Valve: Description and Operation
Negative Backpressure EGR Valve
NEGATIVE BACKPRESSURE EGR VALVE
The EGR valve used on this engine is a negative backpressure valve. It varies the amount of exhaust gas flow into the manifold depending on
manifold vacuum and variations in exhaust backpressure.
The diaphragm on this EGR valve has an internal vacuum bleed hole which is held closed by a small spring when there is no exhaust backpressure.
The amount of vacuum to the valve is controlled by a PCM controlled solenoid valve.
Engine vacuum applied to the diaphragm opens the EGR valve against the pressure of a large spring. With negative exhaust backpressure, the
vacuum bleed hole opens and the EGR valve closes.