Cold Start Idle Surging [Archive] - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum

: Cold Start Idle Surging

02-19-2013, 11:09 PM
I have a 2006 TB EXT. Since temperatures outside have gone down to the teens I Havel
seeing following on startup. Engine turns over fine then immediately rpm drops from initial 1000 rpm idle to half that then surges up again repeatedly until idle steadies out. No check engine light. Have the ability to read some engine data with Torque free app with Bluetooth on Android. Any suggestions or ideas what to look for?

02-20-2013, 07:34 PM
Well for whatever it's worth, I had the same thing happen to my car. Mine is 2004 with under 30k miles on it (very lightly used). It turns out my fuel pump went bad (only because I left the car sitting unused for almost a year so a few other things went wrong too haha :x ).

A couple years ago when I started the car, the engine used to drop well below 500 rpm then back up to 1000 rpm until it steadied out. After the mechanic replaced the fuel pump, no more weird idling! Might even be a resistor or bad fuse, I'd have a mechanic look into it. I'm not sure if mine had to do with cold weather; it just happened to be winter at the time. :D