pbeck1979

So a buddy of mine who is not too technical has a 95 Thunderbird with an '03 Mustang GT 4.6 in it... He has recently developed the typical rev-holding and foghorn sound of a bad IAC... The shop he brought it to has put several different IACs on the car with no result. The last of which being a motorcraft unit for the '03 GT... He and the shop both do not remember if it is the same as what originally was on the car when they started. My question is, being that the car has the '95 Bird computer with a custom tune in it, should it have the IAC for the bird?... Or for the Stang being that that's the motor that's in it? I'm not sure if it makes any difference myself... Hoping someone knows something I don't so I can help him fix this annoying issue. Thanks much...

pbeck1979

No takers, huh?... Ok, if I could just ask then if anyone may have any idea of where else I may post this question where I might find out the info needed? I appreciate the help. Thanks guys...

AzPete

I always was told to swap the computer so it matched the engine....but since you say it is the Birds computer, I would guess it is needing the Birds IAC so the computer can read it right. Do you get any check engine lights? Any codes being read?

Derf00

Yeah 95 and 03 are totally different years, match the replacement electronics to the ECU it has in it.

AZ Pete is right though, normally when you swap an engine (especially with a newer one) you WANT the ECU that matches the newer motor. If your friend didn't do this and simply swapped the engine block, then the correct IAC to use would be from a 95 T-bird.

pbeck1979

Hi, thanks for replying... funny we're both named Pete and from Florida, too... Ironic... If it were my car, I would have swapped the computer also, but unfortunately what is done is done. As far as a CEL, there is surprisingly none, and no codes stored... at least none to do with that. I think there was an old code for a speed sensor or something, but that was it. The car runs really well for what it is, but this high idle thing developed recently, and has us both puzzled... and a few weeks later the foghorn sound from the air box started. For some reason, when the car is idling high(in neutral or in drive), if you switch the A/C off and back on again the car idles right down to normal... most of the time, not every single time. The honking sound comes and goes, as it normally does in the "bad IAC" situation... I'm just a bit stumped that the Motorcraft one didn't make it go right away. I know the aftermarket ones for the most part, are junk, and that people mostly say to stay away from them. I just wish I knew what was on the car before his mechanic started dic*ing with it. My buddy doesn't want to buy a bunch of different parts(IACs, etc.) just to narrow it down... and I don't really blame him. I just can't seem to think of a logical way to determine it without going that route

pbeck1979

Awesome. That's what I was waiting to hear. Thanks so much guys for the help. I'll let him know and hopefully he'll be on his way to getting 'er running as she should

pbeck1979

Ok so I just talked to my buddy, and he had a point that has me a little more stumped now. I didn't realize it was that long since it was done, but he was telling me that the '03 motor has been in the car for 3 years now... and it was running fine all this time until the hanging idle issue developed recently... and that the '03 motor he had put in came with its' original IAC, which it what it had been running with this whole time. Knowing that, now what do you think??? Thanks again....

pbeck1979

Problem fixed... Beer can mod did the trick. Idles normal, returns to idle as normal, and no more foghorn :-)