Start IAC Pos. vs Coolant Temp.

[Eric Stage I]

I'm trying to figure out how this "should" be set up. Why would the IAC need to change with coolant temp. when you have enrichment? Or is it just a "head start" to keep the cold idle rpm higher.

Thanks,
Eric

 

[bruce]

Cold engine takes extra fuel and air to run when it's cold.

Starting at like 80dF strat ramping it up to like 120 by 0dF.
Then reduce the IAC openings as you get the mixture more right.

 

[Eric Stage I]

I experimented with it by setting it at 80 across all temps to see what would happen. I found that on a cold start (30F) it would stumble for about half a second until the IAC went up to achieve my idle setting (1500rpm), and the IAC ended up at about 120.

I used Bob Cunningham's procedure from another post by starting the car at various temperatures and then watching where the IAC wanted to go to maintain idle. I used those numbers to set up the IAC Start position. It worked great!

And Bruce, the curve ended up looking almost exactly as you recommended, with about 120 at 0 degrees ramping down to 80 at about 80 degrees.

Thanks guys,
Eric