Unstable RPMs, Engine Knocking?

HOSSAMENG84

MEMBER
2009 HYUNDAI SANTA FE
2.7L
6 CYL
4WD
AUTOMATIC
140,000 MILES

My car is running perfectly but on idle the RPM starts to play and looks like it is a knocking (sudden unstable firing or something like that which I can feel it inside my car.

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Wednesday, September 13th, 2023 AT 5:27 AM

3 Replies

KEN L

MASTER CERTIFIED MECHANIC
42,949 POSTS

Thanks for the video, but can you open the hood while the engine is idling and get a video of the engine noise, please? The noise can make the engine idle fluctuate so we need to address this issue which should fix the idling issue. Upload videos of the problem so we can see what's going on.

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Wednesday, September 13th, 2023 AT 1:09 PM

HOSSAMENG84

MEMBER
10 POSTS

Sure. Hope that one will be clear enough to hear the engine sound.

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Wednesday, September 13th, 2023 AT 9:31 PM

KEN L

MASTER CERTIFIED MECHANIC
42,949 POSTS

I don't hear the knocking, but I do hear ticking which sounds normal, at most it needs a valve adjustment. Also, I would check for a vacuum leak when the engine is cold only and I would service the throttle body.

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

and

https://www.2carpros.com/articles/throttle-actuator-service

Check out the images (below). Please let us know what happens.

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