1995 Mustang Gt new pcm wont start

bigdumogre375

New Member
Mar 20, 2010
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Ive had this car broke down for awhile now would like to get it goin. It died and was told it was pcm. It had no spark or injector pulse. You could tap the computer and get it to run for short periods of time. When u shook the old computer it rattled loudly inside. I bought a new one from napa. Put it in, and it hasnt start since. The best thing of all is that if you charge the battery fully it will start and run perfect for 40 sec or so then will not restart. I just put a new battery in it from napa as well as told by last mechanic that worked on it. I have had 2 mobile mechanics and one family friend mechanic look at it, getting very frustrated. Does this pcm need flashed? or anything done to it before installing? Im lost thanks
 
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Ive had this car broke down for awhile now would like to get it goin. It died and was told it was pcm. It had no spark or injector pulse. You could tap the computer and get it to run for short periods of time. When u shook the old computer it rattled loudly inside. I bought a new one from napa. Put it in, and it hasnt start since. The best thing of all is that if you charge the battery fully it will start and run perfect for 40 sec or so then will not restart. I just put a new battery in it from napa as well as told by last mechanic that worked on it. I have had 2 mobile mechanics and one family friend mechanic look at it, getting very frustrated. Does this pcm need flashed? or anything done to it before installing? Im lost thanks

The PCM can't be flashed. I would disconnect the PCM harness and check the pins to make sure one isn't loose or bent such that a connection is lost.
 
Cool, I did that, and they all seem fine. The wires themselves felt tight, but I have not done a pin out yet to even see what I have and dont have. Is it possible to have the wrong computer or would that not result in my symptoms? They didnt know which computer mine had nor anything else about it at the store, neither do I. Thanks for the advice so far
 
You may be able to carefully remove or peel back the sticker that the re-manufacturer put on the computer to see what the Ford code is...

T4M0 would be for a T5
U4P0 would be for an AODE
J4J1 is a Cobra

Now, your original post is a bit confusing...

I bought a new one from napa. Put it in, and it hasnt start since. The best thing of all is that if you charge the battery fully it will start and run perfect for 40 sec or so then will not restart.

That seems a bit contradictory to me...

I suspect that this is a wiring issue, but I can't even begin to tell you where to start looking...
 
So the car starts... then the ECU is good.

I would look else where like the CCRM unit, or even a coil, loose engine ground...May be even a starter.... Does it crank at all when you try to restart it?

If it cranks may be it has something to do with fuel

I am just throwing it out there, How long has the car sat? If it has been a long time then i would give it a full tune up.

Good luck man :)
 
No spark or injector pulsing would lead me to think the stator inside the distributor is bad. Those are it's primary functions.... but then you say if you charge it, it runs for a period of time... And be wary in the future of PCM replacement. They very rarely go bad under noirmal operating conditions. My 88 had a cracked windshield and water was leaking onto the PCM for many months before i realized it and it never had a problem. They're not invincible but they are pretty durable. A lot of people that arent real familiar with modern OBD1 and OBD2 computers often mistakenly replace them when the fault lies elsewhere. LIke has been stated, I would verify the comp you have now is compatible for your car. There should be a number on it.
 
I could just be a coincidence it will start with a fully charged battery.PIP's are notorious for doing what they want,when they want,when they fail. I would start with the PIP.