Protege L4-1839cc 1.8L DOHC (1990)
Air Valve: 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.