Idle Speed/Throttle Actuator - Electronic: Description and Operation

Idle Air Control Bypass Air (IAC BPA) Valve:

PURPOSE
The Idle Air Control By-Pass Air (IAC-BPA) valve is a component of the idle speed control system. It regulates the amount of intake air allowed to bypass the throttle valve under a full range of operating conditions.

OPERATION
For cold engine operation (below 140°F, 60°C), by-pass air (BPA) valve function is controlled with a thermo wax element that contracts and expands in response to engine coolant temperature. After warm-up, the Powertrain Control Module (PCM) controls the Idle Air Control (IAC) solenoid valve to maintain idle quality under various conditions.