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Senior Charter Member
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Discussion Starter · #1 ·
OK what is going on? I’ve got a stock ’92 drive train (5-speed donor) with 55,000 miles on it. I have all new wiring, new coil, distributor, and plug wires, etc. No matter what I try (including advancing the timing) the car sputters and the tac drops off around 4,000 rpm’s (under load or not). Feels/acts almost like a rev limiter. Considering new valve springs but think maybe the computer needs to be re-programmed (if possible).
I changed the rear to 3:73's but this problem was happening before the change.
Have swapped out all the sensors, computer, etc. and nothing seems to make any difference. Anyone else have this problem?
 

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I lifted the quote below from Ford Muscle. Your problem sounds similar.

"After a couple weeks Wade Chamberlain, who goes by the handle FFR Cobra on the Corral.net and other forums posted a response which looked to us as being the key to unleash this engine. He suggested that we likely had one of the wires to the distributor TFI module connected to a full-time 12V source, when in fact it should only receive 12V during cranking. He explained that this circuit in the EFI wiring serves to retard timing while engine cranking for faster starting. If the circuit is seeing 12V while the engine is running in effect the timing is being retarded. This made perfect sense, since in fact the 3500rpm break up felt more like a rev limiter then it did a misfire or fuel starvation issue. Wade also added that this is a common mistake when guys convert older vehicles to fuel injection because it is easy to assume that the only connection ever requiring 12V during cranking only is the starter."

the link: http://www.fordmuscle.com/archives/2006/10/DIYEFI/index.php
 

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You could verify the above possibility by doing a total timing check. About 34-36* at full advance is good.

You could also have a bad pick-up coil in the distributor. Hard to test, but swapping in a known-good dist is pretty simple.

HTH
Bruce

Also- the PIP signal (from pick-up coil) is what eventually becomes your tach signal, so if your tach is dropping out, that could be another clue.
 

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You can have strange things happen with these high voltage systems.

I had a situation where my ffr with MSD box was extremely hard to start. Infact, it would not start until the battery was almost run down. THEN MISTERIOUSLY, it would crank.

Also OCCASIONALLY, under hard excelleration, it would fall flat on its face.

ALSO... Some times it would go dead at a stop light and Repeat the not wanting to start until the battery was almost dead.

What I had was a carbon trail up the inside of the coil and back down the outside of the coil... When the battery was fully charged, the high voltage coming out of the coil would take the path of least resistance back to the positive wire on the coil. When the battery was about exhausted, It would quit doing this and go ahead and crank.

We would have never found this except we were diagnosing it in a dimmly lit garage and saw the arch off the coil.

BIZZARE, but true.

lots of luck.

cobraearl
 

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Drew will it rev beyond 4000 or is that as far as it will go? Please refresh my memory, did we use an aftermarket EFI harness? You might want to try swapping a known good Mas Air Meter as well.
Mike
 

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Discussion Starter · #8 ·
Guys, thanks for the suggestions. I will try every one.
Mike we used a painless wiring kit, and a new EFI harness. We have already swapped out the MAS AIR Meter, TPS, and every other sensor.. that waht is making this so weird.
 

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section 8
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Get a noid lite or test lite and connect it to an injector to see if the pulse goes away when the problem occurs .Do the same with an inline spark tester see if the spark goes away . Many times the module goes away. Also " just because it's new doesn't make it any good just new" Remember Fiats they were new once , were they any good, no! Good luck , bob
 
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