I have a 2009 Tahoe with 220k miles, but it's on it's second engine which has around 60k miles on it currently. It has developed an irregular idle that I have noticed when stopped at traffic lights or sitting and idling in the driveway. It doesn't always idle this way, sometimes it idles just fine but I would say it idles rough around 60-75% of the time. Here is a link to a video that I took showing the tachometer as it was doing its thing, hopefully it is helpful and you all can give me an idea of what might be going on.


Thank you all!

 

 

Is the check engine light on? I would look at the vacuum hoses for leaks and deteriorated hoses. This will usually lead to rough idle but is not noticed so much when driving.

 

@jolitsoivia - No, I have noticed it in park, drive and neutral. I will turn off the ac and see what that does when I am driving this afternoon. Will post an update after I do!

@oldchevy - No check engine light on. Could vacuum hose leak also cause a very low but noticeable whistle/air noise? I have noticed that one is audible mainly from the outside of the vehicle but also from inside and the noise will fluctuate with the rough idle.

Thank you both for the replies!

 

Yes, a vacuum leak could cause a noise.

 

I tested turning off the AC this afternoon and did not notice a major change in the idle. I am hoping to check out the vacuum hoses this weekend and will come back with an update after I do!

 

I had that issue with a 5.3L, was fuel pressure regulator.

 

@kevinkpk - Is there a way to test the fuel pressure regulator?