Auxiliary Air Valve (Idle Speed): Description and Operation

Bypass Air Valve:

The air valve, located on the underside of the intake manifold dynamic chamber, is a temperature sensitive valve that is open when cold. It allows additional measured air into the engine, bypassing the throttle valve, for cold start fast idle. As the valve is warmed up, it closes, and the computer controls the idle speed through signals to the ISC (idle speed control) valve.