Occasional Bad Idle

[lesZ71]

I have a 2004 Z71 with just over 50k miles on it. Since January I have been experiencing an occasional low idle...almost to the point that the truck shuts off. This happens randomly, but when it happens it does it a few times in a row, then runs fine for a few days. This happens only when I am at a stop sign or red light and has happened when creeping along in stop and go traffic. The truck drives fine when running at highway speeds and I have not noticed any issues when accelerating. I cleaned the throttle body back in December so i am pretty sure that is not the problem. I tried searching for similar problems on this forum, but the posts I found refer to a potential problem with the Idle Air Control (IAC) valve. From what I understand, the IAC should be on the driver's side of the throttle body, but this location in my truck only has a empty spot there. I have a Hayne's manual for a 2002 Silverado and have referenced it for this issue. All of the symptoms point to a possible problem with the IAC...I just don't know where it is located on my engine! Can someone point me in the right direction? Thanks!

[nickvrebel]

your 2004 has an electronic throttle body so it has no Idle Air Control Valve like the cable controlled models. On the electronic throttle control models the computer activates the servo motor to crack the throttle as needed.

 

Most likely you need to do two things:

1. remove the throttle body and clean it thoroughly - front and back. It's only 3 nuts and a wiring harness disconnect to remove. (I know you said you did this, do it again ;))

2. Clean the Mass Air Flow meter - this is located next to the air filter in the intake tubing, ONLY use the specific MAF cleaner available from auto part stores and follow the directions, other cleaners will leave a residue and interfere with readings. Do not touch the sensor wires with your hands.