Hugger

iTrader: (21)

I installed a hotcam in my 99 Z28 A4 w/ a 3500 stall. I have got the car to where I can just reach in through the window and start it with a bump of the key, no coaxing with the gas pedal. The problem is when the car is completely cold the idle surges up and down by about 200-300 rpms. I have to let the car settle down before I can go anywhere in it. The hot starts are not an issue at all, even with the AC on. The cold start surging is the only issue I can't get resolved. My IACs are in the 30-50 range when warm in park with the AC off. Here are the current changes I have made with LS1edit. So far none have cured the 3-8 minutes of surging that occurs when I cold crank the car.
-Throttle body hole drilled to 7/32 (not going any higher than this!)
-idle set to 875 in park AC off
-VE tables 400rpm x 60%
800-1200 rpm scaled by 79% (calculated value for MAP 50-55)
-Reset IAC park position set to 210
-7 degrees timing added to Base Spark in drive/park tablesup to 1200 rpm - 0.4gm/cyl (this cut down on the tendency for the car to die when maneuvering through parking lots)
-I have also been playing with the P/N airflow decay tables a little
-RAF table values have been slightly increased above 60C

Can anyone think of anything in Edit that could resolve my cold idle surge? I know that I may never get it to completely go away but I would like to try to make it better. Any input appreciated.
-Josh

Cal

iTrader: (1)

Mine does the same thing. I logged the situation with EFILive, and I found that the cold surging goes away at about 100 *F when the system goes into closed loop. What I do is just sit there with my foot on the gas until it does this. I figure it's better for my 918 valve springs anyway to not take off until after some warm up time.

sammysls1

I am pretty sure you have changed your mass air sensor. I had a 99 m6 with a hotcam and never drilled the butterfly, just changed the mass air to an 85mm form slp. it worked on mine.