I posted this earlier today in another area. Thought this area might be more appropriate.

Got a problem. My 06 v10 has 41000 miles on it. It started missing under load when it had ~34000 miles on it. the dealership has tried to figure out my problem and keep coming up with "fuel quality". The codes sent back say "random missfire". The thing is, when this first started I had the filter changed, the tank flushed, and the injectors cleaned and after every time, it would do the same thing. I buy fuel from reputable name brands just to make sure. The last time, they put 10 new spark plugs in it and the miss went away. I filled up with fuel, $75.00 worth, at Sunoco (good enough for Nascar, should be good enough for Ford) and it ran good for ~280 miles. Then it started back missing under load (merging into traffic on the thruway). Ford tells me it has to be fuel related. They changed the plugs again and its OK. Because its "fuel related" they want me to pay some of the cost. They have 20 hrs in diagnostic time, have been on the phone with Ford Hotline, and still I think it will happen again.

Has anyone had this kind on problem?

Also, truck has Banks exhaust on it. The Fuel pressure and sensors seem to be OK.

 

Your dealer is full of it.

Fuel problems are almost always a lack of power, not a miss or back fire

The fact that they replaced the spark plugs and it went away for a little while. Tells me your miss fire may either be a bad Coil or Coil boot. Have they checked them yet?

 

Never heard of that kind of problem on a newer motor... but I agree, the dealer really doesn't know what is going on and is trying to dance around that fact.

COPs and/or boots shouldn't cause a "random missfire". Has the fuel pressure been checked? Sounds to me like a bad pump is a possibility.

Since your problems began while the truck was still under warranty, I would hound Ford to fix the damn thing until it's done, or they buy it back under the lemon law. Try a different dealer maybe?

I would fight them tooth and nail on the "bad fuel" B.S., especially if you've tried a few different brands. If it were simply a fuel issue, there would be far more than just one complaint.

EDIT: Actually, I used to have an '04 F-150 5.4 that exhibited some very similar symptoms... took it in and the fuel pump was replaced under warranty. Had 30,000 miles on that at the time.

 

I very seldom disagree with anyone in here, Scott, but I gotta take a shot at just one of your statements: The random misfire of a COP.

If a COP spikes high or low it will not give the plug the proper power to fire. This usually happens under load. I don't understand the High-Side power failure, but the Low-Side failure goes without saying.

A COP on the verge of failure has casued many a good tech to take a nip now and then. Sometimes it takes dedication on the part of the tech, while he's in-cabin, going down the road with a load on the truck.

But - after all that typing - it could be an injector or its connector; a COP or its connector; or a boot that was manufactured with a flaw.
I just can't see bad fuel being the culprit.

 

This is the second dealer I have worked with. The first, a light and medium duty dealership was sold out, so I brought it back to the dealer I bought it and my mercury from. The fuel pressure was checked and good. The tank has been cleaned out as well as new fuel filter. This problem has been going on since beginning of November. All coils and such are supposed to be OK. The "random" missfire is the puzzle.

 

There is a difference in "supposed" and "is"....and there's a way to make sure. Make 'em re-lick that calf.

 

Gotcha Big Orn... I'm all for an "edjumication"!

Still doesn't make sense though - if a SINGLE COP, boot, or connection were causing the missfire, wouldn't the PCM be able to tell which cylinder it is? When it's spitting out a "random" missfire, my first assumption would be to look elsewhere - something that controls firing on all cylinders. If I'm wrong, please elaborate.

 

Big Orn, That was something of what I asked the service manager. I looked at the plugs that they replaced with only 280 miles them. They did not look bad to me but when they were replaced the misses went away. I put a bottle of fuel addative in but I don't think that woudl cause the problem, though. I wondered how they could tell if the coils were "hot" enough for the plugs.
Denny

 

When they changed the plugs, they had to remove the COPs and boots. If the boots were flawed and had cracks or pinholes in one or more of them, they could have closed them just long enough to let it run right for awhile.

I would take my mind off the plugs and "bad fuel" problem and focus on whether or not they are willing to hook it back up to a WDS (worldwide diagnostic system) and take the truck for a drive. Might help if you load it with something or pull a heavy trailer so the problem will magnify.

 

That's why I read all y'alls posts...

Random could mean anything - even one randomly misfiring. I see your point and it is puzzling, but I can't see how it's bad fuel causing it.

Also, the PCM won't register it unless it's a dead misfire for a certain length of time.

The "under load" part has something to do with the firing, IMHO.

 

I brought the trailer up to show them, the tech road with me while I pulled and the problem was obvious. I do not believe it is the fuel, I have used several different brands and stations and the problem persists. The thing is, I don't think they have any more ideas and was hoping someone here has had the same problem. They have checked everything their books and hotline tells them but I don't think the problem will be solved with another set of plugs.

 

You're talking to one.
That's why I've posted those comments.

1st dealer - North Central Ford - Dallas TX - no help
2nd dealer - Orr Ford - Atlanta TX - changed boots - no help
Logged onto FTE - discussed problem - got good replies.
Took back to Atlanta - No help
3rd dealer - Johnston Ford - New Boston TX - hooked up to heavy trailer - they hooked up to WDS - found problem, fixed it same day.
6 months of problems and was one bad COP, diagnosed in 45 minutes by a good tech that knew how to operate WDS

 

I agree.

Makes sense. I do seem to remember it requiring a set number of consecutive mis-fires, or a percentage overall... but if it's that bad under load, you would think that eventually a code would pop up identifying it? I could be wrong, no direct experience here. Just thinking logically and squeezing as much as I can out of you experienced guys.

I agree again.

Big Orn is experienced and is known for giving great advice on this forum... you won't find much better here!

 

I did have the exact same problem with mine (06 v-10) summer of '06. Went on a 7000km trip to Michigan and back, and developed a random miss fire on the return trip home. My truck only had about 20000miles on it at the time. I managed to get it all the way home, and a new set of plugs fixed the problem.
I know for a fact I had bad fuel that caused it in my case.
These 3 Valve spark plugs are very sensative to fouling. Especially when putting any kind of additives in or octane booster or anything like that.
I also have an 05 Mustang (3 Valve Head) Superchargered and heavily modified, and lots of experience with failed 3-v spark plugs. I've seen many guys on the Mustang forum I frequent have similar problems after bad fuel, additives, or octane boosters etc...
Your problem is in all cylinders thats why the random misfire code. A bad coil or boot would/should indicate a cylinder number.

I know from experience that these particular plugs can be bad, even though they look good. Going back a couple of years when the 3 Valve heads first came out I knew of a few cases where guys had new plugs bad right out of the box. Until just recently there has only been 1 manufacturer for them (autolite which makes them for Ford also) as well, which limits your options.

I would question how they "flushed" your tank, and what did they do to clean your injectors. The injector cleaner itself could have fouled up a new set of plugs.

 

Thanks Dirty Dog and all of you. I think this has helped. The dealership covered everything. BTW, who else makes plugs for this v10.
RD