Lee3333

Latest update-I took out the MAF and TB and cleaned them both. TB was covered in black soot that took a lot of spray and scrubing to get clean. Reinstalled and now the car idles at 3,000 RPM. Drove home and no PO121 code anymore-just a high idle code. I was hoping that the computer would learn by itself, but no luck. I called my Chevy dealer and they told me I had to bring the car in and have the computer recalibrated-takes about an hour to 'relearn' how to operate with a clean TB. Seems rediculous to me-as the TB gradually got dirty, the computer learned to compensate for it and keep running. But if you clean it, then the computer is too stupid to learn how to operate?

Oldblue

the have been several thread for just that issue, it will relearn it just takes many start drive stop turn off cycles, about 10 to 15 from what I have seen!!

Lee3333

That would be wonderful. I have done about 10 so far, and going out to dinner now so will add a few more. Hoping.....

Lucky

Here is a tread for a high idle after cleaning the throttle body. I believe it took a long time for it to settle down.

https://www.chevyhhr.net/forums/problems-service-repairs-42/high-rpm-after-throttle-cleaning-49401/

donbrew

Maybe you should try to figure out why so much crud in the TB? I have heard of it binding the butterfly, but never seen it. And I never thought about cleaning one until recently, I drive 70,000 miles a year for the last 30 years.

whopper

I've seen the TB butterfly get very dirty due to an air filter that came apart and passed a lot of dirty air. So give the filter, it's housing and piping a good look-over.

A belated thank you FRAM for a badly assembled filter where the glue that hold the filter material to the rubber frame fell apart. And thank you for not standing behind your product.

prod

Yeah fram filters have a bad reputation, pretty much anything else is preferable.

Lee3333

Mine just had this black film on it-never stuck or anything. The car just hit 60,000 miles and has a dry cone filter on it which is clean. About to d/c the fuses, then have a nice breakfast, then wash the car (finally warm enough to) then check the idle.
Thanks for all the tips

Lee3333

I pulled the fuses for 3 hours, started the car, and the idle was fine. I let if run for a while then I revved the engine and the idle stayed at 2000. Tried putting it in drive a few times, still would not come down. Tried starting and stopping the engine, no luck. I pulled the fuses again and will let it sit for a while then drive the car to see what happens. But, the main thing is that it was working for a while, so hopefully it will straighten itself out and I won't have to bring the car to the dealer.

donbrew

You need to do many official "drive cycles" to get the learnin' dun.