Escort L4-110 1.8L DOHC (1994)
Auxiliary Air Valve (Idle Speed): Description and Operation
By-Pass Air (BPA) Valve
PURPOSE
The By-Pass Air (BPA) valve increases idle speed during cold engine conditions to speed engine warm-up and prevent cold engine stalling.
OPERATION
The valve consists of a thermowax material that expands or contracts depending on engine coolant temperature. It opens below 104°F (40°C) to
allow bypass air to flow into the intake plenum. Above that temperature, the valve remains closed.
