michiganman5

Ok, this thing has taken some weird turns, so I thought I would just repost and see if a fresh set of eyes might help.

To recap:

Car ran great! - Starter apparently went out. Installed new one, car started, but ran very rough, like a miss, played with it and finally car just died!

Played and played and finally changed fuel filter and car started, but still a miss. More than a bit of white smoke when taking off and starting, very sweet smell. Much less power.

Changed plugs,
Changed wires,

Tracked down miss to apparently cyl #2 (passenter middle plug). When I pull off all other plug wires, gets worse, this one stays the same. Plug appears to be wet when I pull it out. Put a lighter to it, and it WON'T burn, would have thought it would light up????

Checked spark to plug, good spark, replaced plug and wire, no dif.

Put a compression tester on three of the cylinders, all of them were between 155 and 165psi. #2 was around 155. The lowest of the three i tested, but could be the way i did it hand tight compared to screwing the others all the way in.

Car MAY be losing antifreeze, drivin it about a 100 miles since this started and haven't had to put any in. Although last night when sitting the temperature gauge went to about half way, but after going for a second it went down to less than 1/4. Does look a bit low, but could have been that way, don't know.

Now for the VERY WEIRD PART!.....

Since this started, I have gone from 21mpg on average (330 miles per tank) down dramatically. I have driven 86 miles since my last fill up and I am at about 1/4 tank!!!!!


Theory #1: The miss, dead cylinder even though there's spark would make me think head gasket. Although haven't overheated and NO water in oil. This would explain the dead cylinder and possible overheat that hasn't happened yet, but NOT the gas loss. Compression is good though????

Theory #2: Something with the fuel injection for that port, either too little fuel (would explain the dead cylinder), or too much (would explain the extra gas consumption).

Theory #3: computer is goofy and doing something to make it run rough???

Just a wierd set of circumstances since this went from Starter problem, to fuel filter, and finally to a dead cylinder....

Any idea's fellas/ladies? If you have a theory, please explain in detail how to TEST to confirm or to rule out a problem.


Just to make sure we are on the same page, I have done the following:
No water in oil,
NO codes popping up when I put a tester on it,
plugs have been changed
wires have been changed
there is spark to the effected cylinder
driven well over 100 miles, and not overheating
white smoke, mainly upon takeoff and a little all the time
changed fuel filter and starter
Compression tested and appears to be well above what would be concidered low
Seems to run absolutely fine when up in the 50-70 range, can't hear a problem at all


Thanks in advance,

Jay

a_penquin

Try pushing on the connector for the injector, might be loose, no fuel=dead cylinder but you should be popping a lean bank.

My money is on a blown gasket or cracked head

Testing the head gasket. Pull the radiator cap and see if any bubbles come up while the vehicle is running. Perform a leak down test on the cylinder. The white smoke and sweet smell is about a dead giveaway though.

michiganman5

On a whim, I replaced the Coil Pack, thinking maybe weak spark is causing the problem. No help!

I finally broke down and took the car to a mechanic. Put it on a machine that told him that two of the fuel injectors are completely open, as in the computer is telling it to put as much fuel in the cylinder as possible.

Soooooo, he said it's the computer.

Believe it or not, I think I have a new one at home, will swap and see if that helps.

That begs another question. If the old computer is from a v6 mustang (same), but from a 96, not a 94 like mine, will it work?

The one it came out of is a 96 coupe, and the one having problems is a 94 vert, both are v6 3.8l. Should just plug in and go right? Any procedure for doing this besides, turn the car off, pull it off and put the new one back on?

a_penquin

If you have two injectors open I would rather think its two clogged or failed ones instead of the ECU. Take your time with this, as you can already see your into parts swapping and it'll cost you more in the end. Test the injectors at the connector to see if you are receiving the signal from the computer, that will narrow it down to the computer/harness or injectors.

michiganman5

The mechanic guy said the Computer was ordering the injectors open. He is 100% positive this is at least a big part of my problem.

The question is, can another computer work out of another car, or do i have to order one programmed specifically for my car????

a_penquin

I normally stick to same year/same car, but you can try the newer one. Worse thing that happens is it dosent work.

393strokervert

sounds like a Ground problem to me. if I understand correctly, the car ran fine until the starter went out, after you replaced the starter these problems appeared,correct??? if this is correct,check all of the main ground straps & battery cables. just my .02

michiganman5

I don't doubt the change in the starter caused the problem, maybe a short or something. But I doubt the computer would instruct the valve to stay open at all times because of a ground.

Am I wrong?

393strokervert

a bad ground can be a nightmare, especially in computer controlled cars . been there done that.

michiganman5

Hey all,

Thanks for the help.

The problem WAS the computer.

My computer was F4ZF-CC (A4X2). I found a F4ZF-CD (A4X3) for a resonable price ($80 bucks at local junk yard). Told 100% they are the same with the exception of a newer year (new firmware).

Plugged it in and BAM, worked great, purred like a kitten.

Sooooooo glad it wasn't as some had suggested a bad head gasket.

Thanks again,

Jay