Caprice V8-265 4.3L VIN W MFI (1995)
EGR Valve: Description and Operation
The Exhaust Gas Recirculation (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 an Powertrain Control Module (PCM) controlled solenoid valve.
Engine vacuum opens the EGR valve again the pressure of a large spring. When vacuum combines with negative exhaust backpressure, the vacuum
bleed hole opens and the EGR valve closes.