EGR Valve: Description and Operation

Ported Vacuum EGR:

PURPOSE
The EGR valve is designed to accurately supply exhaust gas to the engine, to reduce NOx (Oxides of Nitrogen) in exhaust emissions. This is done by introducing exhaust gas, which contains very little oxygen, into the intake manifold. This reduces combustion temperatures.

Positive Back Pressure EGR Valve:

OPERATION
The EGR valve used on this engine is a positive backpressure valve.
A vacuum bleed valve located in the EGR valve, acts as a vacuum regulator, controlling vacuum above the EGR valve diaphragm.

Exhaust backpressure is passed thru the hollow pintle shaft and exerted on the bleed valve. When sufficient backpressure is applied on the bleed valve, the valve will open. This allows vacuum above the diaphragm to vent to atmosphere. This will result in the EGR valve closing.

NOTE: The negative backpressure EGR valve will open if vacuum is applied to the valve, with the engine not running.

EGR VALVE IDENTIFICATION

EGR Valve Identification: