6 Idle Air Control Valve Fault Symptoms

What Is the Purpose of an Idle Air Control Valve?

To begin, you must have a basic understanding of the idle air control valve's purpose and operation in your vehicle.

Idle air control (IAC) valves, also known as idle air control actuators, are a small device in every vehicle that controls the engine's idling rotational speed. When the vehicle is stopped, the idle rotation speed of the engine is measured. The rotations per minute (RPM) is the unit of measurement. When carburettors were used for mixing and supplying the air-fuel mixture to the intake manifold, an idle speed screw was used to adjust the idling speed.

The majority of idle air control valves are mounted on the intake manifold and are either motorised or manually operated. It's usually near the throttle body on the intake manifold.

What mechanism does this valve use to control airflow? Because it properly adjusts the amount of air allowed into the intake at idle, it controls the engine speed. The intake described here is just a passage for air into the engine.

To allow the engine to get air at idle, the idle air control valve physically flows air around a closed throttle plate. Because it bypasses air, it's also known as an air bypass valve.

Controlling the valve or motor is the responsibility of the engine control unit. The engine control unit is linked to the idle air control valve. It tells the valve to open or close, resulting in more or less air flowing to the engine, and it regulates the idle speed for maximum performance based on several input parameters including engine temperature and electrical system load.

To activate the throttle butterfly valve or bypass the throttle, the valve is positioned anywhere in the engine. Throttle is nothing more than a mechanism for restricting or blocking airflow.

A linear servo actuator, commonly known as a servomotor, operates a plunger to adjust airflow via the throttle in the IAC valve. This servomotor is made up of a digital optical encoder, a lead screw, and a DC motor. The airflow is mostly controlled by the servomotor's position. This position is digitally tracked by the engine computer.

Most modern vehicles now come with electronic throttle control (ETC), which eliminates the need for an idle air control valve.

Idle Air Control Valve Fault Symptoms

Understanding how the IAC valve works can help us better understand the nature of some of the symptoms that signal the need for an idle air control valve, such as:

Irregular/Fluctuating Idle Speed

The most basic and common idle air control valve symptoms are irregular and/or fluctuating idle speed. The idle air control valve regulates the idle speed of a vehicle engine. It is programmed to regulate and maintain a constant engine idle speed, which it will no longer be able to accomplish if the idle air control valve fails. As a result, in some cases, the idle speed will be abnormally high or low, or it may climb and fall repeatedly.

Engine Stalling

Engine stalling or freezing is another common idle air control valve symptom. Your engine needs the appropriate amount of air and fuel to run efficiently. Your engine will be deprived of the air it needs to sustain appropriate idling if the idle air control valve completely fails. As a result, the air-starved engine may stall while running or fail to idle at all and stall as soon as it is started. Find a full car service near me garage online and schedule an appointment for your vehicle with a qualified technician. You won't be able to drive if the vehicle stalls. This is because as soon as the ignition is switched on, the entire valve system will fail.

Overload Stalling

Engine stalls can happen for a variety of causes. If the IAC valve fails, the engine can still run, but it will be subjected to greater stress. If the driver switches on the heater or air conditioner, the engine may become overworked and come to a complete stop. Another sign to check for is if the steering wheel is pushed to one side. To go back on the road, turn off the heater or air conditioner, wait a few minutes, and then restart the engine after it has cooled. While engine stalling is a common symptom, a faulty IAC can sometimes cause the air and fuel mixture to be so off that the engine won't start at all.

More Pedal Pressure on the Brake

We all know how delicate braking is at idle speed when no foot pressure is given to the accelerator to avoid any forward motion. Excessive braking to hold the car steady at a red light might indicate a malfunctioning IAC valve. The automobile is operating at a greater idle speed because the engine is idling faster than usual. As an extra sign of idle air control valve symptoms, drivers may listen to the sound of the idling engine to see whether it is spinning excessively quickly and forcefully, which can also help explain the sensation on the brake foot. Find a vehicle service near me garages on the internet and chat with a mechanic.

Rough Drive

A properly functioning idle air control valve allows the engine to operate at optimum efficiency, resulting in smoother rides. A damaged valve, on the other hand, might create vibrations and fluctuations, causing the vehicle to come to a halt. This is because the valve will allow less air to pass through, causing the engine to tremble excessively.

Engine Management Light Turns On

The Check Engine warning light on the dashboard will turn on if the engine management module detects a problem with the idle air control valve circuit or signal, such as a variable number of rotations per minute. Of fact, the Check Engine Light might be caused by a number of issues, so you should have the computer checked for error codes to narrow down the culprit, even if the Check Engine light is illuminated in addition to the other symptoms of a bad idle air control valve described above.