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Fuel System Home Page > Parts of the Fuel/Engine Management System > Idle Air Control/Linear Flow Valve


Function: Controls the amount of air that bypasses the throttle plate in order to regulate idle engine speed.


Signs of Wear: Irregular idle, stalling.

















The Idle air control valve, or IAC controls the amount of air entering the intake manifold when the throttle is closed. In this way, the engine computer can adjust the IAC position and control idle speed.


The idle air control valve regulates the amount of air entering the intake manifold when the throttle is closed. A small passage way around the throttle body is blocked by the pintle valve of the IAC. As the pintle moves up, more air is allowed past the throttle body and into the intake manifold, increasing engine speed. When the pintle valve moves down, it restricts air flow through the passageway and decreases idle speed. A common problem with the idle air control system is carbon blockage in the small passageway. When this happens, the IAC is not able to control engine idle. A check engine light will result as well a possible stalling of the engine.


Have your vehicle fuel and engine management system checked by an ASE Certified Technician in Fuel System Services. Set a reservation today to visit our auto repair facility on the southwest side of Houston.

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