The stepper motor is part of the idle control valve. An electronically controlled device, the idle control valve is often used in fuel injected engines, and works in conjunction with the car's ECU (Engine Control Unit) to control the idling of the engine. Idle control valves work by opening the throttle valves directly, regulating the air flow through the throttle body.
The stepper motor is located in the engine, next to the throttle body. It connects directly to the idle control valve. The idle control valve consists of an adjustable, moving pintle attached to a rod, powered by a gear which is connected to the stepper motor.
The idle control valve works to deliver and maintain a regular engine idling speed. Factors such as a cold engine, using the car radio or the air conditioning can affect the idling speed of the engine, so the idle control valve neutralises these outside factors, and makes sure that the engine is constantly idling at a level speed. Based on data gathered by a variety of engine sensors, the idle control valves manage the volume of air entering the throttle valves by either increasing or reducing the engine's idle speed to maintain a constant speed. The tip of the pintle is shaped like a funnel and enters into an air passage in the throttle. The level of air in the pintle controls the idle speed of the engine. The extremely precise movement of the stepper motor means the idle control valve is able to accurately adjust the flow of air entering into the throttle. The stepper motor completes its rotational cycle moving in small stages or steps, enabling the opening and closing of the valves with each exact movement. The idle stepper motor is activated/moves whenever an electrical current is applied.
An engine that stalls when idling or struggles/shuts down when the air conditioning is turned on, for example, could indicate a problem with the stepper motor. The idle control valve assists with engine start up in cold conditions. If any of the idle control valve components are faulty, such as the stepper motor, this may prevent a cold engine start. When you need to change the stepper motor, it is vital that the replacement part is compatible with your car. Specifically manufactured for the make and model of your vehicle, the stepper motor is the perfect replacement part.