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Discussion Starter #1
Ok, so the car runs fine most of the time. However, sometimes when it's idling, it sounds like it's skipping every once in awhile. Also, sometimes it just seriously stumbles, won't idle, backfires, and won't rev up.

My boss was convinced it was fuel related. But the last time it did it today (with a full tank of fuel, btw) I was able to get a fuel gauge on it with it barely running and the pressure was a steady 39-40 psi. I told him I thought it was spark related because of the backfiring.

We hooked the computer to it and was able to datalog while it was happening. Everything (almost) looked normal, except when I got down to the Cyl x Misfire Cnt sections:

Cylinder 1 0 misfires
Cylinder 2 0 misfires
Cylinder 3 0 misfires
Cylinder 4 4096 misfires
Cylinder 5 28796 misfires
Cylinder 6 0 misfires
Cylinder 7 0 misfires
Cylinder 8 0 misfires

At fire I thought maybe a coil pack, but 4 & 5 are on different coil packs, right? Boss thinks maybe crank sensor.

It runs normal most of the time, but each driving cycle, it usually acts up once, maybe twice. Do y'all think plugs and wires might fix this? Thanks in advance!
 

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Discussion Starter #4
Wires

Thanks guys! I was thinking the same thing, except I hadn't considered that me moving them around probably finished off an already "coming of age" problem. Boss man even said they look stock (although I highly doubt they are 15 year old plug wires!)

I'll let you know how it sounds tomorrow with new plugs & wires!
 

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Discussion Starter #6
Stand Up

Did I ever mention you should do Stand Up? Because you are soooooooooooooo funny. :zapyth:
 

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Discussion Starter #8
lol you have to admit, you're car's been on a decline lately :tongue:
Ok, you got me there, but it took 15 years for all these problems to surface. I took care of a bunch of problems when I first got it, and I've just been driving it with all these other problems until finally I did the intake swap and I'm trying to iron EVERY problem out (including the ones I've caused with my "changes") lol!
 

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Discussion Starter #9
New Wires

Ok, so I put on the new Spark Plug wires and I adjusted the TPS. Now it runs a lot smoother, even Daniela notices it. It hasn't acted up since, but time will tell! I also closed up the gaps on the spark plugs a little (they were only about a year old) rather than replace them.

GM, it would be much easier to say what HASN'T been replaced on this car rather than what has.....lol I'll be gone for a month, then I'll see what else I can tinker with / replace on the 'Bird!!! Hope everyone has a great weekend! :thumbsup:
 

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Discussion Starter #10
'Bird Saga Update

Ok, y'all. I'm home for a couple of weeks. Daniela said CEL came on again and the car will idle, but when you give it gas, it stalls. I checked it and it is running really bad. This is total deja vu, because a couple of years ago when it started running badly, computer reported a PO103 - Mass Air Flow High Input. I replaced the MAF and car run good for about an hour, then it left me stranded. I brought it to Ford, they had 3 techs running all sorts of tests and finally gave up and said computer. They replaced the ECM with a used one I brought them and my problems were solved.....until now.

I scanned the computer and PO103 is back. I've been having funny issues for awhile and I told y'all this is EXACTLY how it happened last time. So, I figure ECM again, but I am skeptical because WHY are these ECM's frying?

Therefore, my only conclusion is I am going to install the ECM this time, so I can check all grounds, hot leads, then circuit wires looking for shorts and/or opens. Thank you again Chris, for the paperwork/schematics you provided that I will use to check these. A few of you have mentioned that the 94/95 ECM's are prone to failure. Somebody recommended a more stable 96/97 computer that would require I change the wiring harness, but my thought is this: If a 94/95 computer harness has got issues because it's flat out old, the 96/97 is only a year or two younger. So if I disturb another old harness to change over to the newer style, I may be asking for (more) problems, right? I see only a few of the pin-outs are different on between the 94/95 and 96/97 ECM's. Wouldn't it be easier (and less chance of disturbing 15 year old wiring) just to swap those pins on the connector (yes, I have the special extractor to remove those pins)?
 

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Discussion Starter #11
Got 'Er Back!!!

Ok, so I replaced the computer in the 'Bird. Now, I've changed the computer before about a year ago. The part number on my original (and the replacement) is F5SF-12A650-CA with catch code A5W0. well, I found a couple of 94-95 'Birds at the local salvage yard and I pulled a computer out of one, but it was a different number: F4WF-12A650-AD catch code E4A3. Every yard I talked to said you have to use the same computer, but I just took the -AD E4A3 computer and put it in my 'Bird that had the -CA A5W0 computer originally.

I didn't check all the pin-outs on the ECM connector like I originally planned, because I simply didn't have the time. If another computer goes bad, I guess I will have to make time, lol. THE CAR RUNS GREAT!!! CEL is off, starts & runs cold correctly, starts & runs hot correctly. So what exactly is the difference between the -CA A5W0 and -DA E4A3 computers? Strategies? If they both run exactly the same platform, who cares? :zdunno:

After adjusting the base idle to 550-600 rpm with the MAF & IAC disconnected, I adjusted the TPS output to .98v at closed throttle (had to elongate the holes in the TPS). My thinking is everything is adjusted correctly at this point; any opinions?

So, for now, everything looks good. :thumbsup: Daniela is very happy to have her car back. She said it seems to shift smoother (doesn't have that shift-kit hard shift feel that it had). I figured maybe the different computers had slightly different shift points programmed. While I drove it to the city and back to test drive it, I noticed it shifted a little different, too! Nothing bad, just different. Now, on some cars, I've noticed the TPS adjustment affects the shifting of these computer-controlled trannys. Maybe that made a difference, too.

Share with me what y'all know about the different computers, please.....
Thank you!

BTW, as an afterthought, how could these computers sense misfires when they only have a SPOUT output line from the computer to adjust the timing of the EDIS system on these 94-95 'Birds?
 

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the difference is in the tune....technically this is called a "database"....the "strategy" is the master program that uses the numbers within the database to run the whole show

so a different catch code will have slightly different numbers in the database

the pcm uses the crank trigger wheel to detect misfires...it has nothing to do with the spout line for the timing.....each tooth on the trigger wheel registers a PIP (pickup-induction-profile) signal via the crank position sensor.....and since the pcm knows exactly when each cylinder is firing via the cam position sensor, if it doesn't see the corresponding PIP signal at the proper time, then that raises the red flag as a misfire
 

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Discussion Starter #13
the difference is in the tune....technically this is called a "database"....the "strategy" is the master program that uses the numbers within the database to run the whole show

so a different catch code will have slightly different numbers in the database

the pcm uses the crank trigger wheel to detect misfires...it has nothing to do with the spout line for the timing.....each tooth on the trigger wheel registers a PIP (pickup-induction-profile) signal via the crank position sensor.....and since the pcm knows exactly when each cylinder is firing via the cam position sensor, if it doesn't see the corresponding PIP signal at the proper time, then that raises the red flag as a misfire
So are you saying that a dirty trigger wheel and/or crank position sensor could record a misfire in the ECM? Because I left the scanner attached datalogging throughout the test drive and I noticed 4096 misfires recorded on Cylinder 4 again even after I've changed the plugs & wires. Notice the interesting number, 4096 - hmmmm.....
 

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Discussion Starter #15
traditional debris will not affect either the wheel nor the crank sensor....ferrous metal shavings however, will be problematic since it is magnetic-induction based
I gotcha. Thanks, and I'll check it out next time I get 'er on a lift.
 
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