I am about to give up

[rubydist]

Also, be aware that the Ford pcm's have an annoying habit of not always reporting the correct cylinder as misfiring.

When you say it runs a little rough all the time, does it act rich or lean? Does it act like its missing? or just not quite smooth?

As was mentioned earlier, one of those codes could be the result of the other - a little more detail will help direct you.

 

[Bob Gervais]

OK, a few things to think about, and questions.

-Do you know how to get the intake runners off to do the coils? Not sure if you did this yourself or not.

-What brand of plugs are you running?

-Do you have a digital volt meter? Somewhere, I think on v8sho.com, there's info on how to test them with a volt meter. New doesn't always mean good, so it's helpful to check them.

-Inspect the plugs, particularly the porcelain insulation for cracks. They're kinda easy to crack putting them in, maybe one or more plugs has a hairline crack, which would cause a misfire.

 

[SHOZ123]

The coils are almost impossible to test electrically. You can tell when it is dead. But they don't usually fail electrically other than the insulation cracking and the coil shorting out. Look for small cracks under the plug connector.

Are you using new coils or used ones? New ones seem to be relatively problem free.

 

[Eastcoast SHO]

i know how to take the runners off and did this myself, the rear coils are new. i used autolite sparkplugs and did not over tighten them

 

[1995mtxsho]

I will look into that....just one question what exactly should i do? what am i looking for? pictures of what i have to fix would be super cool

It apears kinda like he used tinfoil on his, the heat wrap tape I linked to is thicker and has a fiber weave through it and was bought at Autozone in their "Performance" aisle.

The thread I found the picture in can be found here.

The idea is to take all of the original looming and tape off of the coil wiring harness. inspect the wires, separate them if they are melted together, reinsulate them from eachother (I used the highest heat resistant electrical tape that I could find), and then reloom them together, and then insulate them from the heat.

 

[SHOZ123]

Just get some more loom to go over what is there now. High temp black loom has a gray stripe on it. No way would I use a metal product.

 

[stephen newberg]

I also do not think aluminum foil or some form of metal tape makes any sense in this application.

pax, smn

 

[Eastcoast SHO]

ok here is an update.

today i took the sho for a ride, of course here and there i got on it hard, still idle problem.

after i got off the highway i hit a red light, the car dies, i start it back up, then dies again. at this point the light turned green, started car back up rev it and put it in drive and made it home.

pulled out code reader, read codes, now only one code is showing p0171.

to me this doesnt make sense there is definetly still a misfire or something to make that idle go screwy and make it die after driving hard.

first i get code: p0303, p0171, p017?(this one was the rear bank running lean, dont remember last number)

then it disapears

then i get code p0171

disapears

then codes po302, p0171

disapears

now code p0171

wtf?

 

[three50one]

It's painful, but you need to check out the wiring harness for bad grounds/chaffed wiring.

This may be a stupid question as well, but have you checked for cracks in the manifold to FPR hose? I threw codes for running lean then rich then lean like you have been getting when it wasn't properly secured before.

I've also had the problem that you're describing with it shutting off though not at a light like that. It wanted to stall once warm and restarted if I didn't give it a bit of gas. Once in gear it would be fine. It threw NO codes for this, but it ended up being cut wiring coming from the Rear banks upstream O2 sensor. Have you changed any of them yet? I didn't need the special tool to do it though. Just a normal open ended wrench.

 

[Eastcoast SHO]

i am going to change the o2 sensors this weekend, but i am a little skeptical to think that all this is being cause by the o2 sensors alone, there has to be something else

btw what is the easiest way to get to the front bank o2 sensor, would it be from the top or bottom? by the top i mean i am gonna pull the runners and surge tank again to check the coil wires while that is off, is it easy to get to the o2 sensor that way, i never noticed or was looking for it at the time i had it off before? thanks

 

[Eastcoast SHO]

This may be a stupid question as well, but have you checked for cracks in the manifold to FPR hose?

I have no idea what this is

 

[three50one]

Do you smell gas in the oil?



on the passenger side of the engine. What you're looking for is #1. Chances are you've touched it a good deal lately. It's small and gets brittle.

I don't know which would be easier. I got to it fine from the bottom, but I haven't tried with the surge tank removed.

If the car has any hesitation at all it could be a cut o-ring on a fuel injector. If no hesitation disregard that.

I'd run up there and give you a hand, but that's a damn far drive my man.

Your plugs don't look fouled by fuel, but then again neither did mine.

 

[SHODWN]

Pete, Cut back the insulation on each CP wiring, follow it back 6-8 inches and make sure that the wires are not burnt though. this is what happened to mine and why I started doing to protection on the harness for people back in 03.

More than likely its a engine harness, the older these cars get the more we see of this, I think we have 10 in the shop for this just this year. Dont know exactly where the problem is, but a simple swap always fixes it.

AS for the guy said Ford was bad at listing the wrong Cyl for misfires, that might be true but not in V8SHO's. 100% of the time what the computer says is correct.

 

[Eastcoast SHO]

thanks kirk, i will check it tomorrow since my wife has the jeep now, so i can take my time with this and get it done right the first time

three50one, now i know which one you are talking about, not that hose is just fine, and i remember that i could even pull that hose off at either end

 

[Eastcoast SHO]

another question, would a misfire cause the tranny to shift improperly, or erractly?

 

[SHOZ123]

The misfire it self would not unless it was severely affecting load. But what ever is causing the misfire may be a sensor that is give skewed data to the PCM. This would affect the tranny.

 

[SHOMEX]

If you get a misfire at cylinder 8 it could cause some funny things with the tranny and some other electronics. (this I know for experience)

 

[genob2]

p0171 is a vacuum leak on the front bank. Start the engine and spray brake cleaner around all the intake manifold gaskets you can get to. Get one of those stethoscope looking things and try to find a vacuum leak by listening for it. I've had numerous front and rear bank lean codes over the years with cheap intake gaskets. Your cylinder miss fire code with probably go away when you fix your vacuum leaks. Your car probably runs better when the engine is cold then when it is warm. This is because, once the engine warms up, the metal in the intake manifold expands and makes your "leak" even worse. Stop throwing parts at this problem and start "listening" for it.

 

[Eastcoast SHO]

The misfire it self would not unless it was severely affecting load. But what ever is causing the misfire may be a sensor that is give skewed data to the PCM. This would affect the tranny.

The tranny seems to be shifting at the wrong times but i will wait until this misfire is fix before i make any assumptions

If you get a misfire at cylinder 8 it could cause some funny things with the tranny and some other electronics. (this I know for experience)

unfortunately the misfires have only been #3 then #2

I looked and listened i could not find any vaccum leaks, i am gonna try what kirk and a few of you suggested about the cp wires and see if they are melted together, then i will take it from there and see what happens

 

[SHOZ123]

I would add too this is assuming the coils are not the problem. It is know that the coils shorting out will affect the sensors particularly the MAF.