What are the 5 symptoms of a bad IAC valve?

Many times the engine of your vehicle is running, but the car does not move an inch. This happens when the engine of your car goes into idle mode. The idle air control (IAC) valve is the component of your engine that controls the speed in this state of your vehicle. However, the RPM of the engine’s speed varies with the conditions.

The IAC valve is an essential component of engine management that is connected to the throttle body and controlled by the engine control unit (ECU).

As no part or component of your vehicle is damage-free, so at some point, the IAC valve starts developing difficulties for the driver to start the engine. Therefore, it affects the overall engine performance.

To keep your engine at its optimal performance we have listed five symptoms of a bad IAC valve that can help you maintain the engine life before you are stuck into an extreme issue.

Symptoms of a bad IAC valve

Along with any vehicle problem, you just need to figure out how to diagnose the problem. Fortunately, there are many signs and symptoms from which your engine will tell you about the IAC failure. Some of them are explained below.

Check engine light comes on

The check engine lights are sometimes turned on automatically even when your vehicle is not going through any issue. This happens rarely but whenever you see this light, you must start worrying that there could be a problem in your engine or any probable issue with your IAC valve.

check-engine-light
Source: https://oards.com/

The check engine light will remain switched on when ECU notices irregular revolutions with every minute when your engine becomes idling.

If you are still unsure what causes the check engine light to turn on, the combination of the below-mentioned symptoms may remove your doubts.

Random irregular idle speed

Due to the reason that the IAC valve manages the tasks of engine speed, if the IAC valve does not work properly then your vehicle will start getting intermittent fluctuations in idle speed due to the inefficient performance.

Random irregular Idle speed
Source: https://oards.com/

Your idling speed should be 1,000 RPM and can be more per minute and can be 900 RPM in the next minute. This RPM fluctuation will remain occurring during the whole duration when the engine is left idle. This to and fro RPM fluctuations can trigger other engine problems.

You should take your vehicle to the expert in cases where you notice the continuous irregular fluctuation in the speed of your idle engine.

Rougher engine idling

In older models of the vehicles, the ECU probably does not compensate for the issues concerning the IAC valve. You can expect to have a rougher idling of your engine if you have a bad IAC valve –this is particularly a good indication that tells you the exact location of the symptom, so you can diagnose and replace the component.

Rougher Engine Idling
Source: https://oards.com/

Vehicles with normally working or good IAC valves experience a smooth idling and eventually restoring of the engine is gentle and even smooth. If you do not experience the smooth idling and starting of the engine, then it’s certain that your IAC valve needs to be replaced.

Plus, when your IAC valve is bad, you can also feel vibrations in the idle state of your engine that indicates that the engine is short of enough oxygen.

Frequent engine stalls

A loose battery connection or a dirt fuel injector are some of the reasons that cause an engine stall. But you can notice engine stalls when you have a bad IAC valve as well. The issue of engine stalling develops with the lack of oxygen for the engine to use when idling, and with this, it triggers many other engine issues.

Frequent Engine stalls
Source: https://oards.com/

This is also one of the cases where ECU does not compensate for the issues developed by the bad IAC valve, and eventually the engine stalls.

Initially, engine stalls will be occasional that indicates the initiation of the bad IAC but at this point, you can still use your vehicle. But in the long run, if the problem is not addressed, then your engine may stall frequently.

Vehicle backfires

Your vehicle can backfire if it has problems with the IAC valve and similarly with the other four symptoms it can be the reason for triggering other engine issues if left untreated.

Vehicle backfires
Source: https://grimmermotors.co.nz/

This happens when you take off your foot from the gas pedal and your vehicle starts jerking horrendously and with it, you notice an excessive fuel leakage from the tailpipe which can be dangerous in conditions where the engine is working. If this happens you must check your engine with an expert otherwise, you will put your vehicle in serious issues.

Addressing the problem

However, it is important to diagnose the problem when you opt to fix it beforehand. From the above symptoms, it is easy to tell that your IAC valve is getting bad. Luckily, you don’t need any expert skills if the symptoms are moderate. You can follow these steps to solve fairly mild issues with your IAC valve.

Park your vehicle at the side of the road if you’re traveling and switch off your engine.

Identify the accurate component of the issue. If an IAC valve is involved, find out the exact issue by checking RPM.

Remove the IAC valve located near the throttle body. Look out for the vehicle manual if you can’t find it. Unscrew the battery terminal and attach everything to the valve.

Clean the idle air control valve as the carbon build-up may surround the surface of the valve with a rigid cloth.

If the valve is not that much spoiled then keep the valve in its place after cleaning, otherwise replace the IAC valve to avoid further idling issues.

Now when you know what hinders your engine’s performance and why it is mandatory to look after the IAC valve’s health, you should watch out for the symptoms of a bad IAC valve. And of course, a single identification and implementation can save you from many other long-term problems.

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