2009 Sierra 5.3l, idles up to 3000 rpm after throttle body clean

SeaDonkey45 · April 2, 2012

Took my truck to the dealership because it was having issues of when you come up to a stop sign or traffic light, wanting to keep going, it didnt like to go below 1500 or 2000 rpms. If you take it out of gear, it will momentarily idle up to 2500 and then come back down to normal, THEY said oh yea thats common, probably the throttle body carboned up, we charge 125 bucks to clean that. I said my truck is still in warranty, what the hell? I received no explanation other than that aint covered, I said its an under warranty truck that doesn't run or drive right, how is that requiring a charged fee? Anyway, long story short, I have worked on my own cars for over 25 years, So I took off the MAF and the throttle body and cleaned them both, and yes the throttle body was extremely gunked up, I used only MAF cleaner on that and I used throttle body cleaner on it. I had the battery disconnected the entire time as well. Reassembled and drove truck and it drove just fine it seemed until i pulled back in my driveway, now it will idle up to 3000 or more rpms, and just stay there. I took it back out for another drive and after a few miles it seems to be running fine, UNTIL you come to a stop sign, it doesnt want to stop, and if you take it out of gear, will idle up to 2500-3000 rpms again. Pulled back in the driveway and ran a scan on it, and it reports a B2AA code, I cannot find any such code anywhere, any ideas people? I know the maf is clean and the tb is spotless, I took the cover off and make sure I plugged in the breather tube,etc. I did the relearn procedure from the gm tech section, I did relearn procedure #4, then drove at speeds up to 50 mph for 5 minutes, according to the sheet it only had to be over 44 mph. Starts up idles fine, as soon as you put in gear it takes off on its on, and will run up to about 30-35 mph without ever touching the gas pedal. When you start it up it idles fine unless you touch the accelerator, it then jumps to 3000 and stays there until you turn it off and back on.

tanked_darren · April 2, 2012

Report the dealer to gm customer service. I have never had the "throttle body service" dealer used to try pushing all sorts of things you don't need on me. Unfortunatly service reps are the biggest problem at dealerships.

Try another dealer

Edited April 2, 2012 by tanked_darren

txab · April 2, 2012

I'd re-check all connections, air and electrical. Then disconnect the battery and try again

SeaDonkey45 · April 2, 2012

I have already left the battery disconnected for several hours again, did the relearn procedures AGAIN, its no better.

SeaDonkey45 · April 2, 2012

The weird thing is, it starts and idles perfectly now, where it used to fluctuate up and down even at idle. Its only when you put it in gear or rev the engine that it goes haywire now. I can go out and crank it right now and it will idle like a new top, put it in gear and its almost as if the accelerator pedal is partially pushed, it just takes off. Or if while idling you rev the engine, they it immediately goes to right at 3000 rpms and stays there

michigan2500hd · April 3, 2012

Wondering if the stepper motor on the throttle body is messed up. Happened to me when I took the TB of my 05 5.3L. I found out the hard way that you arnt supposed to manualy open and close it lol..glad it was covered under warrenty

BlackZ71Silverado · April 3, 2012

Opening and closing it manually should not hurt, you have to do it to completely clean it. I have done it several times without issue. Is it possible you sprayed something you shouldn't have? Dealer may need to do an idle re-learn with the Tech-II. If you don't want to do that, drive if for a while (like a few hundred miles) and it should re-learn the proper idle. When yo udid it the first time, probably didn't drive long enough. If the truck was out of warranty, it would cost you maybe $85.00 for the re-learn at the dealer.

The code you should be getting is P0507 = engine idle speed greater than desired (programmed)

You said the throttle body was really dirty. The ECM made an adjustment due to the carbon build up on the throttle body. When you cleaned it, you caused a sudden change to the throttle body function and confused the ECM. It should readjust after about 200 miles or so and be back to normal. You need to take a road trip.

txab · April 3, 2012

Wondering if the stepper motor on the throttle body is messed up. Happened to me when I took the TB of my 05 5.3L. I found out the hard way that you arnt supposed to manualy open and close it lol..glad it was covered under warrenty

You can fark 'em up sometimes

SeaDonkey45 · April 4, 2012

Ive cleaned several TB over the years, I always open and close them slowly and never force anthing, its running better today, I took a 60 mile trip, its still nowhere near good though, I may have to try the techII learn jobby, and yes truck is still under warranty until 48,000 miles.

oh and i used CRC throttle body cleaner in the red can from OReillys Auto Parts

4wd · April 4, 2012

There is a procedure to reset the program after cleaning throttle body.

SeaDonkey45 · April 9, 2012

I took it all apart and checked everything, put it all back together again, did the relearn procedure for at least the 5th time, its all back to normal and running fine now.....I dont know what was up, but I took it apart at least 5 times, I highly doubt, as easy as it is to disassemble that I messed up anything and was correct in my assumption, apparantly the computer was having troubles and now its fine....

4wd · April 9, 2012

I took it all apart and checked everything, put it all back together again, did the relearn procedure for at least the 5th time, its all back to normal and running fine now.....I dont know what was up, but I took it apart at least 5 times, I highly doubt, as easy as it is to disassemble that I messed up anything and was correct in my assumption, apparantly the computer was having troubles and now its fine....

Whatrelearn procedure you used

SeaDonkey45 · April 10, 2012

1 disconnect battery for about an hour,reconnect

2 turn on key for 60 secs and then turn off,remove key and open door to kill battery saver power

3 start truck, run for 3 minutes at whatever idle speed it chooses

4 kill engine for 3 minutes

5 start engine for 3 minutes and allow to idle

6 drive for at least 10 miles at speeds of over 44 mph

I found this on an obscure forum, and printed it out, I cannot for the life of me find the webpage now though, it listed most all gm vehicles, and you choose your relearn procedure by the chart

Frodellio · March 27, 2017

Seadonkey45,

the EXACT same thing has happened to my 2009 5.3 Sierra. Did you end up finding a resolution to this problem? Most worrying part of this problem is the braking when coming to a stop sign. Feels like I have to brake not only again momentum but seems like the transmission is 'Pushing' too. Hope you found the answer!

dan

njrorozco214 · September 19, 2017

My 2009 Avalanche just started doing this exact same thing. How long was it before it started to act normal again cause I pretty much did the exact same procedures that you did except the techII. I am new to the gallery and new truck owner always had cars before