Idling rough at stop lights.....

[jab1327]

Hi All,

I have a 2000 GMC Yukon SLT that I love to death. It has 75,000 and I am the second owner. I bought it in 2002 when it only had 16,000 miles and I knew the original owner. Anyway, lately it has been idling rough at stop lights when it's hot. I put it in netural and it idles just fine. I am not getting a "Service Engine" light so the service computer doesn't show anything. Has anyone experienced the same thing with either your Yukon or Tahoe? Thanks in advance for any input.

 

[JKmotorsports]

Welcome to the site.
A lot of times on higher mileage engines gunk will build up in the air bypass passage in the throttle body and will cause a rough idle. Try cleaning your throttle body and pay special attention to the upper left hand corner where the small opening is. This is where incoming air comes through and is regulated by the IAC when the engine is idling. Also make sure the edges of the throttle plate and the TB bore are clean.

 

[jab1327]

Thanks for the response. I'll have my brother-in-law look at that. I thought I read some where that it might also be the O2 sensor? Do you know anything about that?

 

[ZX1100F1]

Good suggestion, I would also like to add to use a little of the spray cleaner and gently clean off the element in the MAF sensor.

Also with 75k miles you may also benefit from a good fuel injection cleaning (add four-six 12oz bottles of Techron to a full tank of gas) and a new set of spark plugs correctly gapped.

 

[jab1327]

Thanks Dave. I'll look into that. My brother-in-law ran some injection cleaner through it back in January. Not sure what he used, but he did it because the number 3 and 8 value were gummed up. But I also had the "Service Engine" light on so he knew the number 3 and 8 were gummed. Ran great until recently.

 

[jab1327]

Hi All,

I had my brother-in-law take my Yukon back in and one of his mechanics spent the better part of a day on it. He ran tests on the different sensors, cleaned the throttle body and it still ran rough. He just happened to pull a spark plug the gap was off by double. Ended up there were 2 spark plugs bad. He replaced them all and put in new wires. I am happy to report that my Yukon runs like a champ.

 

[drtalksic]

i have a 95 hoe that just recently started to idle real low and almost want to stall if its not in park or i must be on the gas at all times dont know wats wrong and i have searched everywere, if anyone knows wat this might be cause by then please let tme know.

 

[chad_towns]

Sounds similar to my problem but mine only occurs in the winter when I crank it in the morning(when engine is cold). Anybody have any ideas as far as getting instructions on how to clean the throttle body?