Cold start 3rd gen 3sgte issue, RPM and A/F bouncing on cold starts (vids) Options

[mgnt232]

Hey so just now starting to get cold here (30-40 degrees F during morning starts). and my car is going nuts lol. its only on cold starts too, so maybe there is a fix, or someones had the problem.
Anyhow i have vids of whats happening on the cold start, and then like 3 mins later when it warms up just a tad and its fine.
Only at idle as well, if i gas it even a little bit it just holds around 2k and doesn't jump. Maybe i can just tighten up the throttle cable a little for the winter months?
It's fine when warm and driving too, no differences i can notice

Cold start up vid



Warmed up (fine)





This post has been edited by mgnt232: Nov 13, 2013 - 5:48 PM

[Hafkai]

The bouncing idle seems to be caused by the deceleration fuel cut off, with the engine warmed up it cuts fuel till ~1100rpm i think, on a cold start this point could be at ~2000rpm. A vac leak could be enough to raise the idle over this point and it will start to bounce as long as you don´t give it some throttle.