Air By-Pass (AIRB) Valve
WARNING: This page is about a different car, the 1995 Ford Pickup, 1995 Ford F-Super Duty, and 1995 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
The AIRB valve directs airflow from air pump to exhaust system or atmosphere as required. Valve may be mounted on air pump or in-line (remote). AIRB valve is vacuum operated and may be normally open or closed.
Normally closed valve supplies air to the exhaust system with medium and high applied vacuum signals during normal modes, short idles and some acceleration. With low or no vacuum applied, pumped air is dumped through silencer ports of the valve or through the dump port.
Normally open valve with a vacuum vent provides a timed air dump during deceleration and when vacuum pressure difference is maintained between signal port and vent port.