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Discussion Starter #1
I haven't seen this discussed before and it's driving me nuts.

I'm running a bullitt intake manifold on my 95 Bird and I probably bought an iac for a 01 mustang when I did the swap. The car never idled since I did the intake swap. It would just die when I wasn't giving it gas. I ignored the problem because I upped the injector size and maf at the same time and figured I just needed a tune to get it to idle.

I bought an x-cal from Don L. and did the e-mail datalog thing with him back and forth a few times and the idle still wasn't working. I ended up just shimming my throttle body open with a piece of cardboard at the throttle stop in order to keep it from constantly dieing.

I recently made the pilgrimage to Soupercoupes Unlimited to get a dyno tune from XR7 Dave. While Dave was able to get my car running really well on the dyno, he told me that there wasn't much that he could do to fix my idle issue and that it was caused by me using too new of an iac. He said that newer iac's are controlled by a different electrical input and my 95 ecm wouldn't/ couldn't run a newer iac.

After relooking at the 96/97 intake swap write-ups, I didn't see this being an issue. I ordered an new Motorcraft iac that was correct for 96/97 engines (F6AZ-9F715-EB), swapped it out today, and I am having the exact same issue. The car just won't idle.

What am I doing wrong?
 

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Not sure what exactly the issue is. All I can say is when I dropped a 01 mustang longblock in my 95 and plugged my harness in I ran into the same issue. I never got around to getting the setup tuned correctly but had to adjust the TB stop screw to idle the engine. Ran fine like that however it is not the correct way to remedy the problem. You could look at a adapting an 95 IAC to the intake some how?
 

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I put a pi intake on my 95 and something kind of similar. If you start the car and you give it some gas it will die and take some time to start again. I have to start and not touch the gas pedal until its warmed up. Mine idles fine as long as you don,t touch the gas pedal
 

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When i put a pi intake on my 94 I had routed a few vacuum lines wrong and had a few broken hard lines from moving them around ...in 100% sure if it only stays running under load that's the problem..check your tps wiring also because I had to stretch mine to its limit and maybe yours slid out of the back of the connector ...but I'm almost positive its just a vacuum leak..
When I did my swap I also upped the injectors . mafs.3in intake with the pi.75Mm plenum and tbody and deleted the egr and without a tune it ran perfectly fine just a bit rich but it ran and idled just fine once I chased down the vacuum leaks..
 

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I second vacuum leaks. The BIG cams in your signature may be a key contributor as well, unless you're saying you had the issue with the intake alone?

In my experience the IACs used at least through 2004 work fine on these PCMs, I don't mean to contradict Dave on that but he does seem to specialize more in EEC IV SCs so perhaps their IACs work differently. The EEC V 4.6 ones all work the same though, I've used new edge sourced ones on every intake combination, with both my original 94 PCM and the 96 MBE3.
 

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Discussion Starter #7
If I had a vacuum leak, wouldn't that have made itself know and have caused an erratic a/f ratio during the dyno tune?

And as for my "big" cams; that was just me being a little cocky when I made my signature. I don't have the spec card in front of me, but they are either a stage 2 or 2.5 from mhs. They were basically the biggest cams that I could run without changing valve springs or notching pistons, but even then I don't think they are very radical by any means.
 

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If I had a vacuum leak, wouldn't that have made itself know and have caused an erratic a/f ratio during the dyno tune?

And as for my "big" cams; that was just me being a little cocky when I made my signature. I don't have the spec card in front of me, but they are either a stage 2 or 2.5 from mhs. They were basically the biggest cams that I could run without changing valve springs or notching pistons, but even then I don't think they are very radical by any means.
Possibly, I'm no tuner but did it say it was running lean during the tune then he adjusted the tune accordingly but the lean issue may have been just a vacuum leak..
It would t hurt to double check all your vacuum lines and routing ..I know the 94 intake upgrades involve a lot of rerouting of lines and capping of others . just eliminate the easiest 1st.
In sure you have it correct already buuuut is the tube from the iac running into the intake tube between the mafs and throttle body ?
 

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Discussion Starter #9 (Edited)
ATTENTION: To anyone reading this- I still am having issues. Keep reading beyond this post.

________________________________________________________________
Original post-

I pumbed in my original 95 iac valve and... my car idles again! It works.

I have no idea why others haven't seem to run into this issue, but I'm glad that I figured it out. I'll be ordering a pair of remote iac adaptors from MMR and I should be all set.

I should also note the the plug on the 95 valve is different than the 96/97. I spliced in a newer style pigtail when trying to run the newer iac, and now I'll have to convert the plug back to the older style.

I hope this info helps anyone in the future dealing with this problem.
 

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Before running it all rigged like that have you confirmed your new style iac is functioning correctly? Just because its new means nothing . also when you spliced in the new plug connector for the newer iac were your wires correct?
When I bought my iac connector the wires were wrong and the grey not white wires went to the stock harnesses red wire..I say before you commit to that rigged setup try a 96-97 tbird iac and make sure the wires are correct..
I've used many diff year iacs on my 94 and 95 intake swaps and never had an issue and I've done 2 on my personal cars and one on a a buddies.
I will hand it to you..very clever how you rigged up the old style iac on that intake.
 

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I run an IAC for a 99 Mustang on my 95, no problems at all - been on the for over 10 years. It is an OEM Ford one though - most aftermarket are not that great. I agree on a vacuum leak.
 

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Discussion Starter #12
Still driving me nuts. I neatly plumbed in my original iac and- nothing. Still not working.

When I get the engine up to temp, it idles decent. I can adjust the idle rpm with the throttle body screw, and it will sit there just fine at eight hundred rpm. It's just the cold start and coming down from a quick rev that make it stumble and stall.

I can't find any source of a vacuum leak. No hissing. No reaction to starter fluid being sprayed around in the usual areas.

I experimented with flipping the two wires that go to the iac with no change. Does anyone know if it matters if the wires are flipped?

I verified that I am getting twelve volts at one of the wires, but I am not able to interpret or verify a signal coming from the second with just a basic multimeter. Could my pcm be at fault? Perhaps I shorted something when modifying my engine harness...

I am very near to bring it to a dealership and seeing if their diagnostic computers can give more information.
 

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Not sure if this helps but when I installed a '96 Cobra intake on my '96 Mark VIII, I had to tweak the IAC and TB to get it to idle properly.

The car would not run at idle without throttle input. What I did was adjust the TB screw to get it to start and run at a high idle, then started backing off the idle screw a bit at a time while unplugging/plugging the IACV harness connection. I kept adjusting to the point where the car started to stumble with the IACV unplugged but would regain idle with the IACV plugged in. Since you only get a couple minutes for a true cold start, I repeated this a couple times at a cold start and eventually was satisfied.

My thinking was the IACV has a finite window of airflow adjustment and there was not enough airflow with the different intake/throttle body. So the idea was to adjust the airflow at the TB to get into the range where the IACV would control the idle rpm.
 

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On another note. I noticed you Put stage 2 cams on the early heads. The early valve springs can have binding issues. I put comp stage 2s in my 95 engine which had about 90K on the clock. I think I made it maybe 40K miles with the cams. Started with a stumbling idle and acceleration and shortly I broke a spring and valve head snapped off crumbling a piston and destroying the block. The stage 2s were stock lift and had much more duration and closer lsa. I was told I would be fine with the cams as they were stock lift but no one at the time told me the early springs were different.
 

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try to find a iac air box for it I forgotten that part # when I got mine from ford. but that should help it is that little square box with two hoses connected to it and connects to the iac and the intake tube it should help. it looks like a little box
 

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Discussion Starter #16
try to find a iac air box for it I forgotten that part # when I got mine from ford. but that should help it is that little square box with two hoses connected to it and connects to the iac and the intake tube it should help. it looks like a little box
I did manage to plumb that box in with no change to the situation.

My transmission went out on this car, so I won’t be able focus on fixing this until the spring. Thanks for the thought though.
 

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Basic question - you hear no hissing but have you done a vacuum test?
The amount of vacuum you see at idle will go a long way towards definutively confirming if you have a leak or not.

-g
 

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Discussion Starter #18
Basic question - you hear no hissing but have you done a vacuum test?
The amount of vacuum you see at idle will go a long way towards definutively confirming if you have a leak or not.

-g
Good Question- I have not. It was something that I always intended to do, but have not as of yet.

What vacuum range should I be looking for?
 
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