Gmt900 Rough Idle

vdubmurray · July 9, 2009

Hi all,

I just traded in my 07 GMT900 RC Silverado for a new 09 EC Silverado, but everytime I come to a stop, or sitting in park, the idle is rough. I have the 5.3, same as my old truck, and this never happened before. Is this normal? Has anyone else experienced this with the 09s?

Thanks,

Brian

jrrod2004 · July 9, 2009

Hi all,

I just traded in my 07 GMT900 RC Silverado for a new 09 EC Silverado, but everytime I come to a stop, or sitting in park, the idle is rough. I have the 5.3, same as my old truck, and this never happened before. Is this normal? Has anyone else experienced this with the 09s?

Thanks,

Brian

check the gas quality and fill up a few tankfuls and see if it goes away...if not it is time for a trip to the dealership....

vdubmurray · July 10, 2009

Thanks, I'll give that a try first before taking it back. Dealer put the first full tank in so it'll be at least a week before I hit empty.

700 sportsman · July 10, 2009

You could try some Sea Foam and see if it will help that tank of gas out at all

mr_bots · July 10, 2009

I don't think that's normal. Its not just a little rough, the rpm shouldn't be bouncing around that much. I wouldn't try to mess with it any, it's under warranty let the dealer worry about it.

Wires · July 10, 2009

Hi all,

I just traded in my 07 GMT900 RC Silverado for a new 09 EC Silverado, but everytime I come to a stop, or sitting in park, the idle is rough. I have the 5.3, same as my old truck, and this never happened before. Is this normal? Has anyone else experienced this with the 09s?

Thanks,

Brian

If you added a CAI, check if it's connected to the throttle body still. If it's all stock, I'd take it in. It's normal for it to "stumble" a bit when idling (due to the low idle), but having it oscillate on the revs like that isn't normal. My 08 will idle low, and then might stumble and the revs drop 100 RPM, and it shutters a bit, and back up, but not constantly.

ColoradoSkiCountry · July 10, 2009

Take it back to the dealership right away. It is NOT supposed to do that and even if it were bad gas, it would not do that either. Get the Dealer to look at it or at least document it to begin a history.

vdubmurray · July 11, 2009

Hi all,

I just traded in my 07 GMT900 RC Silverado for a new 09 EC Silverado, but everytime I come to a stop, or sitting in park, the idle is rough. I have the 5.3, same as my old truck, and this never happened before. Is this normal? Has anyone else experienced this with the 09s?

Thanks,

Brian

If you added a CAI, check if it's connected to the throttle body still. If it's all stock, I'd take it in. It's normal for it to "stumble" a bit when idling (due to the low idle), but having it oscillate on the revs like that isn't normal. My 08 will idle low, and then might stumble and the revs drop 100 RPM, and it shutters a bit, and back up, but not constantly.

No modifications. Truck only has 190 miles on it. I'm going to call the dealer on Monday. Seems worse today.

vdubmurray · July 14, 2009

Update:

Took the truck into the dealer yesterday. Bad throttle body sensor from the factory. Service manager tells me the whole throttle body has to be replaced, can't do just the sensor? 3-4 days till it gets here.

Zembonez · July 14, 2009

Update:

Took the truck into the dealer yesterday. Bad throttle body sensor from the factory. Service manager tells me the whole throttle body has to be replaced, can't do just the sensor? 3-4 days till it gets here.

Well... at least they found the problem! (hopefully)

ColoradoSkiCountry · July 20, 2009

That sucks. But glad you got it taken care of now. Have they at least given you a decent loaner?

07.5_Z71 · July 20, 2009

I had the same complaint, rough idling, when at a stop sign or red light can feel the shutter in the seat. I look at my rpm gauge and see it fluctuate up and down about 1/2 an rpm, very noticeable. Went to my dealer and was told it was normal for that truck due to the 8 to 4 or 4 to 8 cylinder swap.. I called bull shit, but didn't want my temper to get the best of me that day so I left. I haven't returned for round 2 yet, but will be soon. Have a couple issues since then that it needs to be brought back in for so, hopefully goes better this time. Anyways good luck with your issue, hopefully your dealer is correct on the fix and I can inform mine to check this also...

vdubmurray · July 21, 2009

No loaner vehicle, they said its ok to drive as is until the throttle body comes in.

Typical local service: The dealer said the part would be in last Friday. I called today since I haven't heard from them, and the parts department said they never ordered it yet.

C. Charles Hahn · July 21, 2009

I had the same complaint, rough idling, when at a stop sign or red light can feel the shutter in the seat. I look at my rpm gauge and see it fluctuate up and down about 1/2 an rpm, very noticeable. Went to my dealer and was told it was normal for that truck due to the 8 to 4 or 4 to 8 cylinder swap.. I called bull shit, but didn't want my temper to get the best of me that day so I left. I haven't returned for round 2 yet, but will be soon. Have a couple issues since then that it needs to be brought back in for so, hopefully goes better this time. Anyways good luck with your issue, hopefully your dealer is correct on the fix and I can inform mine to check this also...

The truck won't switch between 4 and 8 cylinders at idle.... it only activates AFM while the truck is rolling and in 3rd or 4th gear. At idle, it's a pure V8 at all times. So yeah, that's BS from the dealer.

C. Charles Hahn · July 21, 2009

No loaner vehicle, they said its ok to drive as is until the throttle body comes in.

Typical local service: The dealer said the part would be in last Friday. I called today since I haven't heard from them, and the parts department said they never ordered it yet.

If it were me, I'd have demanded my old truck back to drive until the new one's fixed, unless they already sold or traded that to another dealer or something.