Originally Posted by
ramjudd
The solution is likely simple, but I keep missing the mark but **this** much.
the symptom: upon start-up, engine RPM initially runs up to 1500rpm (normal) then drops down very low, almost (or does) stall. Rich AFR for the first 60-90 seconds of idle time, then smoothes out to Open Loop FA setting (if in SD mode with O2s off) or to stoic (if O2s on).
All the vehicle's Ive tuned in SD (6) have varying degree's of this hard start issue when warm. The bigger the cam and/or TB, the worse it is. My wideband does show a very rich condition upon start up and on through about the first 60 sec of idle time of about 11:1. I have tried many things to include RAF, IAC Park, StartUpInitial, BAse timing tables, Cranking VE, Main VE down low, etc. The only thing that seems to affect this AFR is adjusting the main VE down low around the idle rpms and MAP. The RAF seems to help a little with the start-up idle dropping too low. But I am still not happy or convinced I am tuning the right tables for this condition. Help me out, gang!!
Robert