Last post on Dec 04, 2013 at 9:10 AM
You are in the GMC Yukon
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GMC Yukon, GMC Yukon Denali, GMC Yukon XL, SUV
#49 of 157 2002 GMC Yukon XL Denali Run/Idle Issues
Jan 25, 2010 (12:38 pm)
Hello to all, I have a 2002 Denali, which had the engine (a used 6.0) replaced after the original took in water. The replaced engine is also a 6.0 but a 2005 and not a 2002. Since the replacement of the engine, the Denali's service engine light has been on, and runs rough (with the service engine light blinking) after you have gave it gas and the vehicle has been at high rpms to pass a vehicle. Recently, the fuel pump and crank sensore were replaced and the codes were cleared, which I thought had corrected the problem. The vehicle ran great with no service engine light for about three days and then suddenly started the same nonsense. Can anyone help? Thanks in advance.
#50 of 157 2002 yukon denali
Jan 31, 2010 (10:24 am)
My Denali just started idling funny. When sitting at an idle, it will every once in awhile act like its going to die then go back to idle again. It also does this when driving it when I come to a stop. I tried it out last night and every time while sitting in park I give it gas then let off it acts like its going to die then goes back to idle again. Any ideas?
Jan 31, 2010 (12:15 pm)
Sounds like you have a dirty IAC (Idle Air Control Valve) which is the silver unit just before the throttle body on the top of front of engine. that could possibly be dirty or dirty fuel lines, dirty injectors. What is the idle at when it is normal, i.e. around 600 rpm or lower? And when you say its getting ready to die, look at the idle needle on the tachometer and if it falls below 400 or under it will die. If you know anyone that has a scanner or a diagnostic tool, it will tell you the code and I can look it up for you. Also, in the old days before fuel injection, we use to have carburetor with air fuel mixture screws and idle screw so that we can adjust the idle to where we want it, but in yours the IAC controls the idle and the PCM ( Powertrain Control Module) controls the IAC. Let me know what happens.
#52 of 157 1996 GMC Yukon 5.7L
Jan 31, 2010 (12:17 pm)
Our Yukon will crank but not start Ive replace the fuel pump and fuel psi reg and still the same thing help
#53 of 157 Re: idle issues [fongerelli]
Jan 31, 2010 (6:22 pm)
So I have replaced the air filter, spark plugs, and fuel filter. I also had the alternator and battery checked for s&g's. Still have the same problem. The vehicle idles around 500 rpm or a little lower. I have not been able to locate the IAC. I have added some of that fuel injector cleaner additive to my tank to see if that helps. When it acts like its going to die it hits about 300 rpm according to my tachometer. I will check that next. It is supposedly on the air intake next to the alternator. Any other ideas if the IAC doesn't pan out.
#54 of 157 Re: 2002 yukon denali [lbathke]
Feb 01, 2010 (8:10 am)
I cleaned both the mass air sensor and the throttle body. It appears to have addressed the problems I was having. There are spray cleaners for both of these items. Just be careful and follow the instructions on the cans.
#55 of 157 Re: idle issues [lbathke]
Feb 01, 2010 (9:40 am)
The IAC is attached on the front before throttle body unit EFI (electric fuel injection) its small aluminum color and has plug to it and it is at the end of the plastic air intake unit where the hose clamp is located. Be careful in handling this unit and spray a special cleaning spray (get from auto parts store) the IAC and re-install it and see if the idle goes back up to 600 rpm. when cold the idles should be around 1,000 or so and after it warms up in gear around 550-650 rpm. If you have the heater or a/c on it affects the idle too so make sure they are turned off. Do some research on the IAC (Google it) or go to u tube and type in "how to clean my IAC unit properly"
I hope this helps.....
#57 of 157 2007 GMC Yukon engine stalls
Feb 16, 2010 (5:44 am)
I own a 2007 Yukon with approx 40K miles. Twice in the past three months the check engine light has flashed on for about two seconds and when that happened the engine derated and then all is fine. The other day on a trip the engine light flashed on and did the same thing. About 20 minutes later it did it again but this time the messages that flashed are stabilitrack disabled, engine power reduced and then the car shut down on the highway going 70+ miles and hour. The car then would not start. My husband wiggled some wires and the car started. We got to our destination and then home no problem. We took it to a mechanic to check the codes before bringing it to the dealer. NO codes showed up on the computer. Any thoughts on what this could be? I drive this car with my children all the time and do not feel safe.
#58 of 157 Re: 2007 GMC Yukon engine stalls [mamom]
Feb 17, 2010 (5:14 am)
Per you description, it does sound like some sort of bad connection. Can you describe what wires did your husband wiggled and if the wires lead to the engine in-take area?