Idle Air Control (IAC) Solenoid Valve
- Forester, Impreza 2.5L, Legacy, Outback 2.5L & Outback Sport
The idle air control solenoid valve is located in the throttle body and regulates the amount of intake air that flows bypassing the throttle valve into the intake manifold during engine idling. It is activated by a signal from the ECM in order to maintain the engine idling speed at a target speed. The idle air control solenoid valve is a stepping motor type solenoid-actuated valve which consists of coils, a shaft, a permanent magnet, a spring and a housing. The housing is an integral part of the throttle body. The stepping motor consists of two paired coils, the coils of each pair being arranged face to face with a shaft in between. The shaft has a screw at the end around which the permanent magnets are arranged. As current flows in the form of pulses through the paired coils sequentially while alternating the polarity, the "N" and "S" poles of the permanent magnets around the shaft are repelled by the same poles of the magnetism generated by the coils. This causes a nut externally fixed to the magnets and internally engaging with the screw of the shaft to turn. The shaft then goes upward or downward. This upward and downward motion of the shaft opens or closes the valve port, adjusting the amount of bypass air. - Impreza WRX 2.0L & Outback 3.0L
The idle air control solenoid valve is located in the throttle body and regulates the amount of intake air that flows bypassing the throttle valve into the intake manifold during engine idling. It is activated by a signal from the ECM in order to maintain the engine idling speed at a target speed. The idle air control solenoid valve is a solenoid-actuated rotary valve consisting of a coil, rotary valve, spring and housing. The housing is an integral part of the throttle body and provided with a bypass air port whose opening area is changed by the rotary valve.for more information, see IDLE SPEED under FUEL SYSTEM.
Fig 1: Identifying Idle Air Control (IAC) Solenoid Valve (Forester, Impreza 2.5L, Legacy, Outback 2.5L & Outback Sport)