Ranger 4WD V6-3.0L VIN U (1997)
EGR Valve: Description and Operation
Typical EGR Valve
PURPOSE
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The Exhaust Gas Recirculation (EGR) valve is designed to reintroduce exhaust gas into the combustion cycle lowering combustion temperatures
and reducing the formation of Nitrous Oxide.
OPERATION
Vacuum Control
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As vacuum applied to the EGR valve diaphragm overcomes the spring force, the valve begins to open. As the vacuum signal weakens, at 1.6 in (41
mm) Hg or less, the spring force closes the valve. The EGR valve is fully open at about 4.5 in (114 mm) Hg.
Exhaust Gas Flow
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The amount of exhaust gas reintroduced and the timing of the cycle varies by calibration and is controlled by factors such as engine speed, engine
vacuum, exhaust system back pressure, coolant temperature and throttle angle. All EGR valves are vacuum actuated. The vacuum diagram is on
the emission decal for each calibration.
