Impulse Hatchback L4-1809cc 1.8L DOHC (4XF1-W) (1992)
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EGR Vacuum Switching Valve: Description and Operation
LOCATION
Top L.H. side of engine, behind distributor.
PURPOSE AND OPERATION
The EGR vacuum valve is controlled by an ECM controlled solenoid. The ECM will turn the EGR "ON" and "OFF (Duty Cycle) by grounding
CKT 435. The duty cycle is calculated by the ECM, based on information from the coolant temperature sensor and the throttle position sensor.
With the ignition ON and the engine stopped, the EGR solenoid is de-energized and by grounding the diagnostic terminal, the solenoid is
energized.
The EGR vacuum switching valve (VSV) is operated by ECM and is normally closed to prevent the EGR valve from opening:
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When the engine is cold.
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When throttle valve is at idle position.
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When manifold air temperature is low.
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When intake manifold pressure is low.
