By-Pass Air Control (BAC) Valve

The BAC valve is mounted on the throttle body. It controls idle smoothness by regulating throttle plate by-pass air. The BAC valve consists of the air by-pass valve which functions during cold engine conditions below 122°F (50°C) and the idle speed control solenoid valve which works throughout the entire temperature range. The air by-pass valve is controlled by the engine coolant temperature. The idle speed control solenoid is controlled by the ECA. The BAC controls, cold engine fast idle, no touch starting, dashpot, hot engine idle and engine idle load correction.