[Murago]

Newbie question here. I have an '89 gt, built from a car stripped for drag racing. Mods/details are as follows: 302 virgin block, .200 dome pistons, Edelbrock Performer RPM heads, B303 cam, GT40 intake, 24lb injectors, 190lph fuel pump, 72mm mass air, 65mm T.B., cold air intake, BBK shorty equal length headers, 3.55 rear gears, aluminumn drive shaft, MSD ignition, 240amp alternator, T5 tranny, Centerforce II clutch, bla bla bla.
My question is, I have an '88 GT wiring harness with a manual mass air computer and mass air conversion kit. The baby runs great (when the key works - read my other post..), but when I push in the clutch, the RPM's hang at 1200 rpm until I come to a completed stop.. My buddy says his doesn't do this - drops to idle when he pushes in the clutch, whatever the speed. What have I missed?

[Screemin3o2]

Sounds like the IAC to me. Does it stumble at all on deceleration or do you notice any difference in divrability when you are on deceleration? I have heard that you can clean them but I can't verify whether or not you are harming anything if you do.

[dcraig8]

it does sound like an i.a.c. those babies go out at 70,000 miles....guaranteed

[99mustang232]

see if your buddy with let you swap for testing?

[Murago]

There is no stumble on deceleration. The IAC is brand new and the idle has done this from the first time I started it up. I read something a time ago in the letters section of a MMFF magazine that there is a resistor missing or damaged in a wire loom somewhere, but I cannot find the issue, however I may have read it wrong.
Maybe I have gotten a bum IAC?

[dcraig8]

you could have gotten a bum i.a.c. but not likely, you may want to try another one and clean out your throttle body, check your vacuum lines and make sure your egr valve is working properly by putting vacuum on it and watching it open and close

[militarygt]

my 94 gt does this also. ive just learned to deal with it but would love for it to stop.

[Murago]

One thing I did forget to mention is that my T5 is an older unit, hence the absense of a neutral sense switch. I believe I wired the unit to show in gear (at least I think) all of the time for fear that the computer would not run the right map during driving; not sure if that input even does that.
I don't think that is the problem though.

My EGR valve is disconnected, I have plugged the vacuum line going to it, but have left the signal wire connected so that the computer knows it is not working. What would the EGR valve have to do with a hanging idle?

[Screemin3o2]

I think you have a normal symptom of driving and it isn't going to go away. Did you get the new IAC from Ford? If you got it from advanced or something then it might not work as good as an OEM part but it isn't anything to worry about.

[Murago]

Really not worried, not a daily driver. Built this car from frame-up, my hobby. I have lived with it for three years; just something on my mental list to try to remedy.

[JBIGBOOTSY]

that is not a real problem there are two Idle settings on when the car is stopped and on when the car is rolling. to change the rolling idle you need an eeciv management unit of some kind, I know the "tweecker" piggyback system lets you change that.