XFI guru's, help with idle

[jjump59]

Car runs great at anything over 1400 rpm. Will not idle when cold or hot, way to rich and i'm not sure where the adjustment is for the cold idle. Any and all suggestions welcome. I can provide any numbers you need to know but i havn't run it in a week or two (other pressing issues) and don't remember them right now. i'll start it up and get whatever you guys need when you tell me what would help most. Thanks.

[parsonsj]

JJ:

I had similar problems which turned out to be IAC-related. We diagnosed the problem by pulling the IAC valve all the way out (so it didn't pass any air) and disconnecting it.

You should definitely eliminate it from being the problem first.

jp

[jjump59]

i'll give that a shot. will probably be this weekend now as i just got race car engine back and need to get it installed for this weekends race. thanks

[Blown353]

Way too rich at idle?

Once it's warmed up the cold start enrichment should be out of the picture (check anyways-- enrichment vs. coolant temp) and then change the VE table in the idle cells to try and lean it out.

If it's still too rich even after you lean the affected cells on the VE table there's a chance you are getting MAP AE fuel at idle-- check for that on the dashboard, MAP AE happens real quick so you may have to datalog at the highest rate to see it.

I had an IR setup on a Mustang that was pig rich at idle. I struggled with it for one day then the next day the lightbulb turned on... the computer was adding MAP AE fuel at idle making it go super rich. I had to tweak the MAP AE table and the parameters for the MAP AE to make it less sensitive to manifold vacuum fluctuations, problem solved.

[PTAddict]

JJ:

I had similar problems which turned out to be IAC-related. We diagnosed the problem by pulling the IAC valve all the way out (so it didn't pass any air) and disconnecting it.

You should definitely eliminate it from being the problem first.

jp

I had the same problem with the older FAST and a Holley 4-barrel throttle body. Turns out the Holley IAC has a different pinout scheme than a GM IAC - it's a Mopar equivalent - and the FAST assumes you're using GM. Using the wiring schematics in the Holley and FAST manuals, I repinned the IAC connector and it worked fine.