Could it be the ECU? - Muscular Mustangs
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post #1 of 21 Old 07-14-2004, 06:18 PM Thread Starter
 
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Could it be the ECU?

We came across a dead cylinder on our 94 Cobra and by doing a full diagnosis, this is what we found:

On "pre-ignition", injectors 4 and 8 will maintain a constant voltage of 10v and remain on. The other injectors don't stay on, but voltage is at 3v?!? I've looked at the wiring harness and can't find anything in the middle that can influence voltage as described or is responsible for how the injectors fire.

I'm personally thinking it's the ECU, but that kinda seems unheard of..

Any ideas?
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post #2 of 21 Old 07-14-2004, 09:39 PM
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Have you checked all of the wiring, connectors, etc from those two injectors back?
At first i was going to say maybe it could be the injectors but i think it would pretty far fetched for two injectors to go bad at the same time. The only thing i can think of is that somehow they are wired "together", such as having the same ground or power source inside the ecu and that connection/wire has alot of resistance somewhere (such as its grounded) creating that constant voltage.
It's hard to say for sure because usually an ecu is either working or not, but i've seen weirder things happen.
If you've checked the wiring all of the way back to the ecu then i'd go with the ecu as the culprit.

Where are you located? If you are close to me i'll let you swap computers with my car to see if it works out otherwise maybe you can find somebody in your area with a 94-95 cobra that will let you do that swap to see if it is the computer.
Otherwise the worse that can happen is you buy a computer, see if that's the problem and if not you can always sell it on ebay/stangnet/corral again.

Oh well, i hope that helps a little



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post #3 of 21 Old 07-14-2004, 09:41 PM
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After posting that i saw under your name where you are from. I doubt you'll want to push the car all this way to swap computers, i'm in PA...LOL




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post #4 of 21 Old 07-14-2004, 10:08 PM Thread Starter
 
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Quote:
Originally Posted by quick5pnt0
Have you checked all of the wiring, connectors, etc from those two injectors back?
Yep sir.

Quote:
At first i was going to say maybe it could be the injectors but i think it would pretty far fetched for two injectors to go bad at the same time. The only thing i can think of is that somehow they are wired "together", such as having the same ground or power source inside the ecu and that connection/wire has alot of resistance somewhere (such as its grounded) creating that constant voltage.
yeah.. that's something I didn't think about..

Quote:
It's hard to say for sure because usually an ecu is either working or not, but i've seen weirder things happen.
If you've checked the wiring all of the way back to the ecu then i'd go with the ecu as the culprit.
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post #5 of 21 Old 07-14-2004, 10:10 PM Thread Starter
 
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Quote:
Originally Posted by quick5pnt0
After posting that i saw under your name where you are from. I doubt you'll want to push the car all this way to swap computers, i'm in PA...LOL

We live in an apartment complex upstairs and I have trouble breathing when I go to my car for work in the morning.
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post #6 of 21 Old 07-14-2004, 10:12 PM
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LOL, been there



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post #7 of 21 Old 07-14-2004, 10:14 PM
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Off topic:
How did you get your production number for your Cobra? Call SVT?



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post #8 of 21 Old 07-14-2004, 10:32 PM Thread Starter
 
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Haha, a lot of people ask me that..

It's a pretty sweet deal, I was reading the site for scoa.org and came across an option to acquire my SVT certificate. I just called 1-800-FORD-SVT and they asked for my VIN.. couple weeks later you get a real nice certificate and a letter from the president of SVT, not to mention it's free! <- Sounds just like a commercial.

I bought a frame for mine and hung it up.
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post #9 of 21 Old 07-15-2004, 12:10 AM
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That's it, i'm calling tomorrow.



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post #10 of 21 Old 07-28-2004, 07:05 PM
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Tough one

Its tough to diagnose this one sitting here in front of the computer. However, I would say your injector driver is going.

Swapping out the computer would help. Any 5.0 Cobra computer could at least idle the car, I would think. Wish I could be of more help.
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