I am new to DIY PROM , but I have a question that I have yet to find a straight answer on by searching.

Has anyone run across anything in their tuning that would add a set number of IAC steps when the car is rolling? The car is stock 89 LB9, stock 5 speed bin.

I have a manual car that idles at 1000-1200 rpm when the car is rolling. If it comes to a complete stop, after a few seconds, the idle drops to a comfortable 700 or so. The datalog shows about 20 or so IAC counts being taken out after being at 0mph for several seconds. It is annoying when you pull up to a light to have such a high idle, then finally drop.

I want to reduce the number of IAC steps that are added when MPH <> 0.

I have searched and found info on the “throttle follower”, but I think the idle issue is a different. This high idle when rolling issue has been observed before in old posts, but I did not find a definitive answer on how to tune it out.

Somewhere in the code, if the MPH is non-zero, 20 or more steps are added to the IAC.

Any idea how to tune these added IAC steps out? I would love to fix this aspect of the stock tune. I have looked at the $6E hac, but I am an ME, and my programming knowledge stopped with FORTRAN 77, so I have a long way to go.

Any insight here is appreciated.

 

On are on the right track with the throttle follower (TF). At location $57A is the minimum TF steps while moving. Reduce it a bit at a time until it returns to idle OK. You don't want to go too far as that can cause RPM dips and possible stalling.

RBob.

 

I had the same issue with my AXXD tune. I manged to fix it by decreasin the throttle follower settings until it acted the way I wanted it too.

I just put the car back to stock, and now have to do it again. It is very annoying to say the least.

I am not familiar with the 6E stuff, so I can't give you specifics other than messing with the throttle follower.

-jason

 

Thank you for the reply RBob, that is the exact information I was looking for. I will report back with results when I get to run the car with the changes to the bin.

 

You are right about reducing it a little at a time. My stock bin had "07" at $57A, and just changing it to "05" seems to have fixed the high idle when rolling problem. Thank you very much for your help. After 10 years of driving the car with that issue, I was finally able to fix it the right way!