This will be the most amazing automotive DIY ever and will save you hundreds or thousands of dollars.
Our ’02 Yukon Denali has been suffering from erratic idle at low speeds, especially with the air conditioner on, and occasional stalls at low speed, usually turning but not always. Querying Google for Yukon/Tahoe DIY information is generally useless but I did find these nuggets:
http://gmcowners.com/gmc-forum/showthread.php?t=15028
http://answers.yahoo.com/question/index?qid=20090820223923AA1m67n
They suggest replacing a bunch of stuff to start. The BMW had some stalling issues but its computers are great and always tell you exactly what’s going on. It suggested changing the camshaft position sensor and after doing so, the stalls disappeared. So I thought I’d follow the above articles and my own experience with the BMW and swap out about $700 worth of parts.
But the part about the throttle body intrigued me. I figure it’d take an hour and $2.00 worth of carburetor cleaner.
So, get your carburetor cleaner from WalMart for $2.00 or any gas station for $4.00 and some shop towels. Pop the hood.
First we have to remove the tubes/baffles going from the air filter to the throttle body shown here:
Yukon/Tahoe Intake Pipe/Baffles
It’s a really funny shape with a big empty baffle below and that long empty baffle on top to the right. Remarkably, this large assembly is only held on at three places.
Loosen the hose clamp near the throttle body:
Yukon/Tahoe Throttle Body Pipe Clamp
Loosen the hose clamp near the air filter:
Yukon/Tahoe Air Cleaner Pipe Clamp
And the tricky part, disconnect the keeper holding the tube to the coolant hose. Get a very small flat head screw driver to depress the lock and wiggle the keeper apart:
Yukon/Tahoe Keeper
Now pull out the assembly and you should see this:
Yukon/Tahoe Throttle Body
Push open the top of the throttle plate and you’ll see a thick layer of black carbon on everything. Get your carburetor cleaner and blast it on all the surfaces around the inside of the throttle opening (called the venturi.) Get your shop towel and while holding the throttle open, clean as far in as you can. Clean the back side of the the throttle plate (butterfly valve) as much as you can. Take some time here and make sure it’s spotless. Be sure to remove any fuzzles left by the shop towel. We don’t want them in the engine.
Yukon/Tahoe Throttle Body Areas to Clean
Put it all back together and make sure the engine starts.
That’s it!
For us: IT WORKED!
The erratic idle is gone, the stalls are gone. Unbelievable.
I’d give it a 1.5 on the difficulty scale. Anyone with a bit of mechanical skill should be able to do this fix.