Getting a FAST 92 to idle on cold starts...
 

Hey guys before I go into this I just want to throw out there that I have ported the IAC opening on my fast 92 tb out a good bit I can probably go more but i dont think I need to at this point.

Ok, when I start the car up on a cold start it will start but then either quickly drop down to 200rpm or so and surge until it eventually finds itself and levels out after about 5 secs. The tps reads .53v which is up from yesterday. When I first installed it I would have to hold the pedal open to get it to start, I turned the set screw a 1/4 turn and got it to this point but i cant go anymore due to tps voltage.

My Iac counts are around 20 hot and a cold start puts them in the 160's. To me at least this says that at cold idle the car isnt getting enough air and with the tb open as far as it can voltage wise I need to force the IAC open more to allow a stable start.

My issue is I dont really quite understand how to do this. I see the IAC effective area tables but even after reading threads and stickies I'm really not quite sure what to alter. Can anyone give some tips or lend a hand?

Below is a tuning log of a cold start this morning and a small drive to school along with my current tune.

Why did you port the IAC opening? The car should start and idle atleast halfway decent with that manifold. Check for vacuum leaks. Is it still a MAF car? I'll check your tune file a little later.

-Dave

the IAC port on the fast 92 tb's are known to be very small and cause issues. I just opened it up a bit to give the IAC more authority. And I dont think theres a vac leak anywhere. All new gaskets in the manifold, fuel trims on both banks are very close to 0 and if I unplug any of the vac lines the idle quickly speeds up. After it warms up for a min or two it idles fine at 825 just like I want it too.