4 Symptoms of a Bad Idle Air Control Valve
Is your engine running rough, stalling, or simply not starting? A faulty idle air control valve could be the culprit. This vital exhaust component regulates airflow and keeps your car running at a perfect idle.
Understanding how the valve works and recognizing the symptoms of a bad idle air control valve can help you identify the problem early and fix it before it becomes a bigger problem.
What is an idle air control valve? The idle air control valve (IAC valve or IAC) is an electrically operated valve responsible for controlling the engine’s idle speed. It plays a vital role in ensuring that the car runs smoothly without stalling when stopped (idling) without the accelerator pedal being depressed.
Where is it located? The idle air control valve is usually located near the throttle body. It is usually small and mounted on or near the intake manifold. You may need to check your car’s service manual for the exact location.
How does it work?
When you stop or park your car, the engine continues to run, but it is important that the engine does not stall and waste fuel. In most cases, the engine will idle between 600 and 1,000 rpm. If the idle speed rises above or falls below this range, the idle air control valve steps in to increase or decrease the speed accordingly, ensuring the engine runs smoothly and efficiently.
The idle air control valve is controlled by the engine control module, which receives input from various sensors in your vehicle. By monitoring the electrical system load and engine temperature, the ECU can adjust the idle control valve to maintain an optimal idle speed.
The 4 Most Important Symptoms of a Defective Idle Air Control Valve
If your car has a defective idle air control valve, it can exhibit some strange symptoms. Many of these symptoms will affect your ability to drive and operate your vehicle. That’s why you need to take them seriously and take your vehicle to a repair shop as soon as you notice them. Below are the top four symptoms of a faulty idle air control valve.
1) “Check Engine” Indicator Light
Because the idle air control valve is part of the engine, the engine control unit regularly monitors its condition. If for any reason the control valve fails or is defective, the engine control module will illuminate the “Check Engine” indicator light on the dashboard.
Of course, just having this light on probably won’t tell you exactly what’s wrong with your engine. There may be a defect in an engine related part, but at least you will know that there is a problem.
2) Engine Stall
There are many causes for engine stalling. One of them is a faulty idle air control valve. For the engine to stay idle, it needs to receive a certain amount of air.
If the idle air control valve is not working properly, the engine will not get any air. This will cause the idle speed to be abnormal and the engine to stall.
3) Fluctuating Idle Speed
If your engine has an unstable or fluctuating idle speed, the idle air control valve is often the culprit. Ultimately, this control valve is intended to regulate the engine’s idle speed so that the engine stays at a normal speed level.
If the valve is defective, it will not be able to perform its function. The result is a fluctuating engine idle speed. The speed will be very high above 1,000 rpm or below 600 rpm. Sometimes the speed may fluctuate back and forth. If this happens, you can be pretty sure that the idle air control valve is to blame.
4) Engine Won’t Start
Though rare, a faulty idle air control valve can also cause your car’s engine to not start. The faulty valve causes a distorted air-fuel mixture. If you experience any of the above symptoms, you need to address your idle air control valve problem as soon as possible. Otherwise, you risk getting stranded and your day could be ruined in no time.
How other sources affect the IAC valve
Vacuum leaks can affect the idle air control valve and cause poor engine performance. When a leak is present, it destroys the vacuum pressure that helps control air and fuel. As a result, the IAC valve can no longer properly control the idle, which can result in rough idling or even stalling of the engine.
Throttle body
Defects in the throttle body can also affect the IAC valve. The throttle body determines how much air gets into your engine. If it’s not working properly, it can cause your engine to idle rough. The IAC valve needs a precise supply of air from the throttle body to function properly, so it’s important to make sure everything is in good condition.
Temperature
Temperature plays a role in IAC valve functionality too. When your engine is cold, the IAC valve helps to regulate the engine idle speed, allowing for a smooth and proper warm-up. But if your IAC valve is faulty, it might not adjust correctly with the changing temperatures, leading to poor performance and potential engine damage.
Carbon Buildup
Carbon buildup can negatively impact your IAC valve’s performance. Over time, this buildup can accumulate and create a barrier that prevents the valve from opening and closing as needed.
This can lead to erratic engine idling, stalling, or even a complete engine shutdown.
Cleaning the Idle Air Control Valve
To help you get the most life possible out of your idle air control valve, you need to clean it periodically. This maintenance task is not as complicated as you might think. You don’t even need to be a car expert to figure it out. Of course, you’ll need to disconnect the air cleaner hose with a screwdriver. This will help you see the throttle body where the valve is located.
Now you’ll have to remove the idle air control valve by detaching the battery cables and removing the screws from the valve. Make sure your vehicle is completely shut off or else you might get an electric shock. When you have removed the valve, you’ll want to spray it with a carburetor cleaner.
You can also go ahead and clean the throttle body too. Once the cleaning is done, reconnect the valve and cables back in their original positions.