Hi guys, I am making great headway tuning my MAF tables and getting my cammed 327 to idle well and at the proper RPMS. One thing I can't get rid of are ~15 commanded IAC counts when the car is completely warmed up, in drive (the ALDL programs, both winaldl and Tunerpro, show that my manual park/drive toggle is working correctly). I zeroed out the "warm park IAC counts", and when I flip the toggle into park mode with the car warm, sure enough, I get zero counts and the car comes down to its target idle. As soon as I flip into drive mode, the car adds 15 IAC counts, which puts it around 150 rpms over target idle. I'd like to get rid of these in drive! I based my tune off a 1989 6E AYPY (corvette 6 sp manual) bin file. The only thing I can see that is slightly suspect is a "T/F" in gear IAC adder in the constants table (Tunerpro). What is T/F? (throttle follower?). I don't have a VSS, although I'm spending the 70 bucks to get the retrofit kit so I can run one with my Muncie 4 speed (I really want to be able to use the IAC as a throttle follower correctly, and have highway cruise mode active). Is this T/F IAC adder causing my problem at idle? The IAC jumps from 0 in park, hot, to 15 in drive, instantly when you toggle the switch, every time -- this isn't a random occurance.

 

Out of curiosity, see what is at hex address 52B. If it's 15, try changing it to 0. If it's not 15, then it's not the right number.

Edit: Oops, I mean 0f. I just checked APYP (not AYPY) and that isn't the right number. There are a few 0F's in that general area though. Maybe experiment with changing them one at a time?

 

This is being caused by a VSS error. To work around it until the VSS is installed zero out location $57A. That location is TF steps added when > x MPH and in drive. Because of the VSS malfunction the MPH value is being set to x+1.

RBob.