I have been having a problem with my car and cold idling since I installed the new motor. THe engine runs very rough and the rpm surges between 500 and 1000, up down, up down, etc. Once warmed up, even for a minute it all clears up and settles at about 800 in park. After this no problem. During the cold period if I go to put it in gear or turn on the A/C, the engine will bog and eventually stall. This seems to me to be fuel related, I think too rich. Any takers?

 

Oh yeah...sounds exactly like what mine used to do.

I set the IAC vs. Temp higher when cold.
IAC park to run delay set to 20 seconds.
Max Cold RPM in Kickdown mode set to 1400 rpm
Max RPM for Hot park/nuetral set to 1400 rpm
IAC bias for hot restart set to 15 (cut in half basically)
Time for hot restart enable set to 3 seconds
Start-up SA Decay multiplier turned down at low temps
Throttle follower was turned almost all the way up

This is for my 7747 ECM. You might not have the same things but I hope this gives you and idea. On a cold start my engine will idle around 1200 rpm for a while. High enuf that if I pop it in reverse it won't chug and die.

I also have ALOT of stuff done to the O/L AFR tables when cold. There seem to be alot of added tables to the AFR on different starting conditions, this includes the choke. I ended up turning alot of mine DOWN as it would always die and smell like gas. I have a very mild engine combo and I think it was flooding out.

Here's my disclaimer: I may have my tuning theory all backwards but this worked for me.

 

Thanks for the advice. I do have the 730 ecm but I will look to see what tables I have that are similar. I agree with you about the engine be flooded during cold operation because I smell fuel from the exhaust.