Car Engine Shaking At Idle

car shaking at idle speedI wanted to thank you for having a helpful column. Most mechanics charge $29.95 for guys like me to ask a single question!


I drive an Olds Alero with about 112K miles on it.. I’ve been having a shaking problem. It only shakes when I come to a stop and I’m in gear. or I start up the car and put it into gear….First my mechanic said it was the motor mounts.. got those replaced and most of the shaking was gone.. then another mechanic told me it was a problem with the steering.. (covered under warranty) but I’ve been back to the shop 3-4 times and still my car is shaking.

I’m wondering what it could be. I’m going to have my transmission and A/C systems looked at, as the car shakes more when I turn on the AC..

I’m really confused! Is there any advice you can offer?


Good day Steve

Are you sure they replace ALL the motor AND engine mounts? There might be 4? Make sure all got replaced.

Here is a good video on how you can check your engine mounts

I would first check the base idle, it sounds like the engine is idling too low and when you have the a/c on you are placing more load on the engine so if the idle is too low to begin with and you turn on the a/c it makes it idle even lower. Having low idle speed, and or worn or broken engine and transmission mounts causes a vibration, which you feel inside the vehicle.

I would also clean the throttle body and the idle speed control motor and make sure the base idle is set to specs. The throttle body is the main source of engine idle speed complaints. From surging idle speed to dies at idle complaints, start with the throttle body first.

Here is a video showing me cleaning the throttle body, I would recommend you try this too and see what happens.

Please share this with your friends,

Austin C. Davis

Posted in: Running Problems

3 Comments on "Car Engine Shaking At Idle"

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  1. Josh says:

    What could be wrong?

    • By Austin Davis says:

      I would try a tune up first to rule that out. Also make sure there is not a vacuum leak under the hood somewhere…listen for a hissing noise with engine running.

  2. Josh says:

    My 1999 oldsmobile alero 4 cylinder does the same thing the shaking is very light with the A/C off but when its on it gets pretty loud like a mini earthquake not really loud from the outside but you can hear it inside im thinking i may need the coils for the cars tune up cause it hasnt had coils in a long while but other than that the car is in great shape

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