MX-3 V6-1844cc 1.8L DOHC (1993)
Idle/Bypass Air Control Valve: Description and Operation
PURPOSE
System regulates the amount of bypass air entering the engine to provide for quick warm-up and to maintain idle stability and good driveability.
LOCATION
Bypass air control (BAC) valve is beneath the throttle body.
OPERATION
The air valve is the thermowax type that is open when cold to allow extra bypass air into the dynamic chamber. This raises idle speed to shorten
warm-up time and ensure good driveability. As the thermowax element is heated by engine coolant, the wax expands, gradually closing the air
valve. After engine warm-up, the ECU controls the idle speed control solenoid valve to maintain good idle quality under a wide range of operating
conditions.
CONSTRUCTION
The BAC valve consists of an air valve that functions only when the engine is cold, and an ECU regulated idle speed control solenoid valve that
operates throughout the engine speed range.