I recently purchased a 2002 Ford F250 SD with the famous/infamous V10. The truck was owned by a woman who used it to pull her horse trailer on occasion, the truck is in great shape with a tad over 161K. The truck was running fine when I got it, the only problems were a shudder in OD and an exhaust leak. I was aware of these problems and the price was adjusted accordingly. I had all of the manifold bolts replaced at a local muffler shop, which took care of the exhaust leak. The next step was to have the plugs changed and the transmission serviced, I also had the air/fuel filters changed along with the EGR valve. I had a local shop do this for me, using Napa parts and Bosch Iridium plugs. I picked up the truck last Thursday and it was smooth as butter, ran better than when I took it up there and the transmission shifted like a new one with zero shudder in OD, but it didn't last long. I drove it a short way, turned it off for a few minutes then when I started it back up, I noticed a miss, not a bad one and barely noticeable. It doesn't miss at idle, only after I put it in drive. Took it back to the shop and put a code reader on it, came up with a misfire on #4 cylinder. The shop manager, whom I've know for years, said it was a COP. He had the delivery guy bring a new one from Napa, installed it, but it was still had the small miss. I wasn't in a hurry to get the truck back and he was pretty covered up, so they didn't get a chance to look at it until today. I just got off of the phone with him and he said something about the code not resetting and it might need to be driven for a while before it would reset. I really don't think that is the problem, I believe it is one of the aftermarket boots that were installed. Any ideas? Suggestions? I may be wrong, but I am inclined to believe that the miss is the result of something that was installed, in that there was no miss when I took it up there. The spark plugs that were removed were burnt pretty bad, I'm not sure if they had ever been replaced. Any help/suggestions would be greatly appreciated!

 

Replace them with Motorcrafts. The modular engines tend to be pretty picky about their plugs.

Still there? Swap #4 COP with another one that's easy to access.
Still there? swap #4 injector "" "".
Still there, investigate base engine (compression, etc).

All he has to do is disconnect the negative battery cable while he's changing the plugs again. The computer will completely reset in about 5 minutes or so. There are more elegant ways of doing it, but that one is completely and 100% effective.

 

Thanks for the quick reply. Dang, could have sworn that I read somewhere that the Bosch plugs were a good alternate to the Motorcraft. But looking at the old plugs that came out of it, they were burnt pretty bad and the truck wasn't missing. I guess I should have left the plugs/boots alone, it wasn't missing. Live an learn I guess. Thanks for the info, I will pass it along to my mechanic.

 

check your cat converter, i just got mine out of the shop they said the partially plugged CAT was chewing up the plugs,,,, he said the same thing, use only motorcraft,,, i put others in and still getting a stumble on the passenger side as well.

 

It's definitely not the cat, I had that taken care of when I had the manifold bolts replaced. I passed along the info to my mechanic, he assured me that he would take care of it, whatever it turns out to be. Thanks for the suggestion, hopefully I will get the truck back tomorrow.

 

Well, that turned out to be a lot easier that I was expecting. A set of Motorcraft plugs and a new COP on #4 cylinder and the truck runs great. Actually, I am amazed at how good it runs. When I bought the truck it wasn't 100%, had an exhaust leak and the dreaded shudder in OD, now it is as smooth as butter and I am a happy camper! Thanks a lot for the great advice! My mechanic didn't say it but I know he was skeptical about changing the plugs, but it worked. Again, thanks for the info!!

 

A replaced COP always requires a new plug. Keep an eye on your grounds, particularly corrosion on the - battery clamp.

 

A replaced COP always requires a new plug


That is good to know, but I can't get my feeble mind wrapped around the why of it. So, are you saying that if I had just replaced that one plug on #4, then more than likely I would have achieved the same results?

 

That has been my experience. I didn't see the why in it either, so I tried not replacing the plug when I replaced the coil. It still had the miss, and the miss went away when I replaced the plug. I remember asking this question when I was in the throes of my COP problems. I never cured my chronic COP problems until I fixed my ground issue.

 

https://www.ford-trucks.com/forums/1...-not-plug.html

 

Well, thanks for the heads up on the corrosion issues. They use a lot of salt on the roads in the winter around here, so I will need to keep an eye on the cables and such. I'm a little hesitant to brag on how well the truck runs now, afraid that I might jinx myself But, dang, it is running really good! Thanks for all of the replies!

 

I just bought a 99 250 v10 116k
literally 1 mile out of the hole pooped a plug. private sale seller rigged it to sell it.prior to that it seemed smooth
fast forward $400 something later shop did the heli coil like repair 1 plug and coil. It still has a sort of stumble with little load at low rpm
I changed all 10 plugs myself and its still there (motorcraft plugs)
I would have had shop do it but they wanted $1000!!!!
I was looking at some aftermarket COP set ups for like $60 for all 10
Am I wasting my money on them? I figure A shop would get
me $100 just to look at it so it could be a good gamble if a coil is a coil
Have any of you ever used global automotive parts ? E BAY
any suggestions? is there a way i can figure out my issue?

 

^^^^ While I appreciate trying to save a buck or two keep away from eBay COP's unless they're Motorcraft. Sure they're more money but from personal experience there's nothing advantageous about cheap COP's. I use NAPA's better brand and pay only $50 each---considering I'm driving a van with a few OEM original COP's with over 275K miles I'd say the better brands make a lot of sense.

If your engine has a misfire due ignition issues the CEL should be lit up---if so get the codes read and share them with us.

As a side note its better to start your own thread rather than tacking another issue onto an existing one---too often it gets lost and the situation never really addressed.

 

It would need to be a SEVERE misfire before any CEL comes on, if at all, if it's an OBDI system.

 

Thanks I will start a new thread next time
I have no CEL
I am going to throw 10 COP's at it
at 116k it wont hurt I just did the plugs so I'm sure they are original