Cleaned Tb, Now Has Funny Idle

[az'03Silverado]

Ok guys, on Saturday I went to work on my truck, an '03 Silverado ECSB with the 4.8L. I changed the coolant, hoses, serp belts and T-stat. I couldn't get the coolant hoses on the throttle body off so I just removed the three nuts and pulled the TB off the studs to get to the back side. This throttle body has the drive-by-wire system but the throttle plate opened pretty easily. I used some TB cleaner on a rag and wiped all the surfaces and got the thing really clean. I even sprayed the cleaner through the idle hole above the butterfly. Replaced the gasket with a new one and torqued the nuts. I notice, now, however, that when the A/C is on (as always in AZ) the idle goes up to about 1000 rpm's when I take my foot off the brake. It's not that noticeable except for when I'm doing the 'Jaws' thing looking for a parking space at Home Depot. With the fast idle it's kind of hard to keep the reins pulled in. Did I screw something up or is this normal with a clean throttle body? Do I need to disconnect the battery and do the 'relearn' thing? Like I said, it's ONLY WHEN THE A/C IS ON. It DOES idle really smooth however, just fast at times. Thanks!

 

BTW, the cooling system works really well. I even backflushed the fins on the radiator.

[Bish]

I'd guess you plugged the Idle Air Control. It is a plunger type thing that installs on top of the TB. If you cleaned the TB, you could have forced some crud into the IAC. It comes out with 2 bolts. I would pull it and clean it and try again.

[redvett]

Do not spray carb cleaner on the part that is on the outsides of the throttle body. Damage will occur, clean only the pintle and port in the throttle body.

[az'03Silverado]

BISH, Everything on this one is riveted onto the outside. There's just a black plastic casing with a big electrical plug for the drive-by-wire. Nothing is removable.

 

Redvett, I only sprayed the port inside the throttle bore. No cleaner went onto the outside. The actual throttle plate was cleaned with a rag soaked with TB cleaner. There's the main throttle bore where the butterfly sits and then there's a small by-pass bore up to the top (about 1/4 to 3/8 in. in diameter). This is the port that was sprayed.

 

Thanks a lot for your responses. I really hope I didn't mess anything up. I'll drive it for a few days and see if it clears up. But, if it doesn't, then what?

[z85violator]

BISH, Everything on this one is riveted onto the outside. There's just a black plastic casing with a big electrical plug for the drive-by-wire. Nothing is removable.

 

Redvett, I only sprayed the port inside the throttle bore. No cleaner went onto the outside. The actual throttle plate was cleaned with a rag soaked with TB cleaner. There's the main throttle bore where the butterfly sits and then there's a small by-pass bore up to the top (about 1/4 to 3/8 in. in diameter). This is the port that was sprayed.

 

Thanks a lot for your responses. I really hope I didn't mess anything up. I'll drive it for a few days and see if it clears up. But, if it doesn't, then what?

 

 

 

 

when your standing in frt of the truck looking under the hood there is 2 sensors mounted on the right of the tb with torx head screws, one is the iac and the other is ?, . redvett was saying that if you spray the inside of the tb some gunk could have landed in the sensor port. so take the two sensors off and clean them and the ports

[az'03Silverado]

Again, there is NOTHING on my TB that is removable. It's an '03 with drive-by-wire. The IAC is integrated. There is only one module and it is riveted permanently to the side.

 

However, after driving a couple of days and doing the idle relearn procedure it's all cleared up and drives perfectly.