I am having trouble with the idle. No matter what I change I can only get the idle to come down when I unplug the IAC. (500 rpm's)
I have lowered the IAC steps Vs. coolant temp about 20 steps in each box and set the target idle to 550 it ia a little lower but still at 775. I set the high idle (choke) at 1100 and that is working right.
Can anybody help?

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Chronologically challenged. But still kicking!
'92 CAMARO RS
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Are you using a VSS?.
If you're just running it in place, yes, you can confuse the ecm.

Do you have the min idle speed set right?.
IAC passageways clean?.

Target idle of 550 might be lower then the idle stall speed saver.

 

Also, there is an Idle Speed IAC Step Counts Vs Coolant, that is different than IAC Step Counts. The Table I mention is the one I had to play with to get my car to come to a steady idle.

It is not (or was not) defined in the 8D.TDF and I had to add it to my TDF via TunerCat's TDF Editor and help with a "hac" for the 8D. You may have to do a similar thing.

Also, there are constants for IAC Learn that are not defined but should be. They are controlled by Coolant Temperature and if you are running ANYTHING other than a 195*F T-stat, these table entries should have the coolant range changed to ensure that IAC Learn is working. Even a 180*F T-stat is too cold for the IAC Learn to work, unless you modify these constants.

And lastly, as Grumpy said, there are "constants" for the Stall Saver. These are a "fail safe" and may need to be tweaked too if you go beyond their settings. Again, I had to add these to my version of the 8D.TDF via TunerCat TDF Editor.

Look for a "hac" on your 746, and get TunerCat's TDF Editor (it has a 30 day free trial) to define those constants. There is a LOT MORE in these eproms than is often defined. And sometimes these must be tweaked.

 

Grumpy: Yes everything is set right. It idles at 500 with IAC unpluged.

Glenn: You may be on to something there, I have a 180 stat. I will look into that.

Thanks.
Don>>>

 

For the 8D ECM the following constants control IAC learning (at least this is how it reads):

IAC MIN MOTOR KEEP ALIVE LEARNING

HEX...Ex....DESCRIPTION
699...40....Default Keep Alive Motor Steps
69A...171...Learn When Cool > 86.7 C
69B...192...Learn When Cool < 103.3 C

ARG = (DEG C+40) x 256 / 192

This is on the hack sheet I have, if anyone has something different, please correct me.

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[This message has been edited by MadMax350 (edited July 08, 2001).]