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GMC Yukon Start Stall Idle Problems



  • 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.
  • 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.....
  • mamommamom Posts: 2
    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.
  • rshtrsht Posts: 277
    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?
  • mamommamom Posts: 2
    Not sure on exact wires but I believe they did go to the engine intake area. he also changed the relay??? Had our mechanic look it over and he said all wires looked ok-nothing obvious and b/c no codes were detected there's really nowhere to start. Spoke to the GM dealer local to us and basically said the same thing and wait til it happens again-not very comforting. Seems odd that a vehicle can completely shut down and the computer doesn't pick up any codes.
  • Important. If you have to replace a your 02' IACV, GMC will make you buy the WHOLE Throttle Body Assembly @ a cost of $850 bucks. They will not sell you the IACV individually, and you can not buy it new from any WEB SIGHT parts house. The ones they claim FIT, ARE THE WRONG APPLICATION!

  • Clean throttle Body!!!! U may need to replace the Throttle position sensor or Idle air ( manually clean it out. 80% of your problems will begin in the Throttle Body!!

    FYI............GMC will not sell U a Idle Air. They make you by the Whole $850 TB assembly. Dont attempt to buy from Online auto parts house! They will not fit!!!!
    Model's referenced 2000-2002.
  • mrkuhlsmrkuhls Posts: 3
  • so how many miles do you have on the suv? did you check the brake fluid level? Or it could be a loose wire to the computer? I need more information that this?
  • mrkuhlsmrkuhls Posts: 3
  • mrkuhlsmrkuhls Posts: 3
  • kehlkehl Posts: 3
    been havin problems with our yukon starting. so we had it narrowed down to the ignition switch, brought it to the dealer and had it replaced. it ran great for a little over a month. then it started losing power when we were driving. i would press the gas pedal then nothing. the car died on the side of the road, we sat for a few minutes then crawled home. next day started fine then it started acting up again. i was pretty sure it was the mass air sensor so i bought one from the junk yard put it in the car ran great. turned the car off after my test drive now its doing the same thing it did before the ignition switch was replaced. there is a clicking noise in dash when i turn the key but it wont turnover the ignition lights dont turn on either. starter will spin if jumped but the car will not turn over. any suggestions im at a loss
  • Sounds like the fuel pump is gone my friend. Had the same issue with my 04 Denali XL and it was losing power on the highway. Replaced it myself and it now runs like a champ. Also if you see that your gas gauge and miles to empty are changing from how they used to be...its definitely the fuel pump. Mine did the same and once I changed still wasn't showing the right miles to empty but on the second fill up it went back to normal. A month later and she's still running like a champ.
  • kehlkehl Posts: 3
    but would the fuel pump cause the car to not ever turn over. the only sound i hear is a faint click in the dash
  • gmcustsvcgmcustsvc Posts: 4,055
    I am from GM Customer Service. I would recommend at least taking it to the dealership and have the vehicle diagnosed. That way you’re not guessing what the problem is, and you can figure out how to proceed from there. Thank you.
    Mariah GM Customer Service
  • kehlkehl Posts: 3
    hey mariah
    thanks for the advice but we did take it to the dealer when the ignition switch was replaced and they couldn't find any codes or anything else wrong. they told us the only thing they could think of was the ignition switch. 500.00 and one month later here we are again. we got the car to start this morning with an ignition fuse, but as soon as the car warmed up the acceleration problem started again. we called our dealer everyone is scratching they're heads. so if anyone out there has any clues we would be happy to be enlightened. so far we have replaced the starter relay, the neutral safety switch, the ignition switch and the mass air sensor
  • ed_derieued_derieu Posts: 1
    Cleaning the IAC worked for me. FYI it was not that dirty so clean it anyway.

  • benculvbenculv Posts: 2
    About a week ago my Yukon started to have a starting issue. It will not always start on the first try but always starts on the second. There are a few things that I found while trying to diagnose this problem. It dosen't matter if the engine is hot or cold and it only happens about 50% of the time. If I turn the key to the on position and wait about 3 seconds and then turn it to the start position it starts every time. One other thing I found was if I try and start it on the first try it cranks but does not start and then I release the key to the on position it continues to crank for about 2 to 3 seconds. I then turn it to start and it starts right up. At first I thought it was fuel pressure problem but seeing that it continues to crank after releasing the key from start to on I was thinking it may be an electrical issue with the ignition. If it does start and I release the key to the on position it never continues to crank. It runs fine after it's started. I appreciate any help in where I should look or what to try next. I am leaving on a fishing vacation next week and I will be towing my boat and I would like to try and fix this before I go.
  • Did you ever get a response to this starting issue? Im having the EXACT problem with my 06 Avalanche... Chevy says bring it in and if its the ignition cylinder Im looking at 600 bucks.
  • benculvbenculv Posts: 2
    No response from anyone on my issue from this site. I did talk to someone else about this and they told me to try changing the fuel pump relay. They said it was the easiest thing to start with. I am going to get one tonight and try it.
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