Auxiliary Air Valve (Idle Speed): Description and Operation

Fast Idle Valve:

PURPOSE
Increase cold idle speed for smoother idling, non-computer controlled.

LOCATION
Mounted near the throttle body.

CONSTRUCTION
Alloy housing with a encapsulated thermo-wax plunger surrounded by engine coolant.

OPERATION
When the engine is cold, the engine coolant surrounding the plunger, allowing additional air to be bypassed into the intake manifold so that the engine idles faster. When the engine reaches operating temperature, the valve closes, reducing the amount of air bypassing into the manifold.