i have max 100 steps commanded in bin for IAC. using what i thought was stock bin open loop coolant/choke/open loop map values as well as the multiplier for time on.
surges badly 800rpms-12/1 AF to 1700 rpms-17/1 A/F.
i removed 25 steps at max(net 75) and tapered off the remainder to about 3 steps at higher coolant temps. i also enrichened the open loop/coolant, added more choke, did not touch map. increased the multiplier to .99 for more time on choke. i think net commanded in bin is about 9/1 A/F to about 11/1 A/F till choke times out per my calc. now surges 800-1400 rpms and 12/1 to 15/1. when temps hit about 140 deg F on coolant it gets much better. is plenum seeing heat? CL is an immediate smooth idle at 170F. air temps 40F on cold engine start. seems the ecu is seeing a potential stall and adding iac steps and that enleans it and revs . then choke enrichens rpms drop and back to the nasty cycle. is the cold plenum taking away the functionality of choke? should i give up on cold weather tuning as in barn in a couple days for winter storage?
tunercat says open loop coolant + OL map - choke value is net choke A/F. 7747.

 

On a cold engine, there is no fuel compensation for IAC movement (with the 42 code, as I remember). So if the engine starts to stall, the IAC may move enough to drastically lean the motor, but then as the motor crosses the high rpm threshold to exit anti-stall, it again moves, so you wind up with the RPM moving around, as the IAC tries to prevent a stall, and then exits the anit-stall strategy.

You just have to match the choke AFRs, commanded idle speed, and cold start timing, to what makes your engine happy. In cold start situations, calculated AFRs may be off from actual. An engine below temp., is no where near as effecient as one that's warm. With thick oil, and cold heads, a commanded AFR of 12:1 might be closer to 13:1 actual.

 

thanks. i guess i am on right tract. i will dump in more choke below 140F and see how it responds. tuning without wideband would be nearly impossible(for me).