1999 GMC Yukon Engine idle while in gear.

Tiny
PILOT99Q
  • MEMBER
  • 1999 GMC YUKON
  • V8
  • 4WD
  • AUTOMATIC
  • 129,000 MILES
I seem to be noticing when I shift into drive the idle of the engine is not as smooth as it once was. It feels a little rough. But once I accelerate the engine seem to run smoothly. Do you have any suggestions to what could be the problem if there is one?
Friday, February 27th, 2009 AT 3:37 PM

1 Reply

Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS
https://www.2carpros.com/how_to/how_to_tune_up.htm
You may have a vacuum leak, get a can of spray gumout, spray the vac lines and maniflod area, when the idle changes, youve found the leak! You want the engine running and spray on the outside but do direct the stream onto the hoses, if it is a vacuum leak, the engine idle will change speed, then you have detected a leak, repair the vacuum leak and see how it runs! If that doesnt do it, you may need a new idle air control valve, it's bolted to the throttlebody
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Friday, February 27th, 2009 AT 3:43 PM

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