Very bad idle in cold weather, where to look at?

[JamesLinder]

You should buy the Don Maslic book for specific information on tuning a GM LS engine; I've only found this for sale on his website but it is the absolute best single book I have found the past 10 years I've been studying EFI. If you go to Amazon.com there is a fantastic book on Eng Mgmt Systems in general written by Jeff Hartman. Once you read and understand these two books you will be well on your way!

[JamesLinder]

See this post regarding what worked for me for cold start surging and the
engine dying. Took me a long time to figure this out trial and error.

http://www.hptuners.com/forum/showthread.php?t=41010

[Vetal]

James, I have Jeff Hartmann book already.
Unfortunately, from your post I cannot figure out what is so wrong with mine...

Guys if anyone have noticed, there is strange thing going on - sometimes IAC position keeps decreasing towards 0, where car usually dies or if I'm lucky idles at some 350rpm.
What could be the reason for IAC position to gradually go to 0???

[eficalibrator]

Guys if anyone have noticed, there is strange thing going on - sometimes IAC position keeps decreasing towards 0, where car usually dies or if I'm lucky idles at some 350rpm.
What could be the reason for IAC position to gradually go to 0???

The IAC is going down because the ECM is trying to decrease the idle air mass for idle. This is likely because whatever it's calculating for airflow at idle is not matching your actual airflow (See my injector data error post above!) and the resulting adjustment is WRONG. If the estimated airflow was really accurate, you would find that the ECM airflow adjustments for idle control would be a bit more realistic and plausible, perhaps avoiding the forced stall you are seeing.