Car Idles High And Accelerates On Its Own? The Solution

Idling is the process of making a car standstill while the engine is on, but the vehicle is not moving. It happens when no gears are engaged, the acceleration pedal is not pressed, and brakes are activated. Idling is needed in many situations, such as when you wait for the traffic signal to turn green or when you don’t feel the need to turn off the engine. Sometimes idling increases the RPM high until the engine is fully warmed up. But the problem arises when RPM is still set to high even after the engine warm-up is done. If you are encountering car idles high and accelerates on its own, here is your solution.

Car Idles High And Accelerates On Its Own – Why the Engine Idles High?

What does it mean when your car idles high? When a car idles high, it means that the engine is running at a faster speed than it should when the vehicle is in a stationary position and the throttle is released. Normally, a car’s engine should maintain a consistent and relatively low idle speed when it is not in motion. Several potential causes can cause a high engine idle:

Faulty or stuck idle air control (IAC) valve

The IAC valve is responsible for regulating the amount of air that bypasses the throttle plate when the accelerator pedal is released. If the valve becomes stuck or malfunctions, it may allow too much air into the engine, causing the engine to idle at a higher speed.

Vacuum leak

A vacuum leak occurs when there is an unintended intake of extra air into the engine. This can be caused by a cracked or disconnected vacuum hose, a leaking intake manifold gasket, or a faulty brake booster, among other things. The additional air disrupts the proper air-fuel mixture, leading to a high idle.

car idles high and accelerates on its own- the real reasons
It is effortless to troubleshoot the problem by referring to the codes (Photo Source: Bloomberg)

 Throttle body issues

A dirty or malfunctioning throttle body can affect the proper functioning of the throttle plate, which controls the amount of air entering the engine. If the throttle plate doesn’t close fully when you release the accelerator pedal, it can cause the engine to idle at a higher speed.

How can you handle this issue? Sometimes, it is effortless to troubleshoot the problem by referring to the codes. If you encounter some error code blinking there, you can either use the code reader or take your car to the professionals.

If there seems to be no error code, then you can check the Idle Air Control Valve/Bypass Air Control or have it checked. There may be debris in there that can be cleaned, and the idle problem gets solved.

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Possible Causes Of High Idle Speed

If the car idles high and accelerates on its own, there may be reasons. Consider these reasons way identifying the actual root of the problem.

  • Sometimes the power circuit malfunctions, and it is responsible for high idling.
  • Perhaps there is a fault in the cooling system which makes the engine overheat.
  • The fuel pressure regulator can be a reason that either needs a repair or replacement.
  • You may need to work with the Ignition timing.
  • A leaking hose can be the culprit.
  • There may be some issues with the engine control system.

You see the reasons can be the many that cause the idle issue to happen. In case you can’t find the actual root, it is always advised to take the vehicle to professionals.

car idles high and accelerates on its own- the reasons
You see the reasons can be the many that cause the idle issue to happen (Photo Source: ctmirror)

Why The Engine Accelerates On Its Own?

Sometimes with high idling, you also encounter that the engine accelerates automatically, even if you do not give any command. The malfunctioning throttle body can be the culprit that if sticks can cause acceleration. Check out car Maintenance Tips and resolve all the issues.

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The most common reason can be the floor mat that can make the pedal stuck. As a result, the pedal does not return to its accurate position, and this causes acceleration. You can get the throttle checked and tell the repairer to replace it if any problem exists.

You can check the floor mat yourself and make sure in no way it interferes with the gas pedal. Nothing should be stuck in the gas pedal; clean the area to crosscheck.

car idles high and accelerates on its own
The most common reason can be the floor mat that can make the pedal stuck (Photo Source: hotcars)

Conclusion

In the end, you should always have the error codes diagnosed. You can either solve the issues yourself or take the car to professionals and get the ‘car idles high and accelerates on its own’ issue solved.