I have a 2000 F250 V10 with ~120,000miles. The other night it started to run rough at idle. Sounds like a missfire- really sounds like the truck has a wicked Cam in it. Runs fine up and down the road except when I come to a stop- the miss goes away when you run the rpm up over ~1000-1200.

No codes. Ran a full diagnostic at a local shop and it only showed intermittent missfires, but could not pinpoint the problem.

I have cleaned the IAC, replaced the spark plugs and coils. Cleaned the MAF, reset computer... I am clueless. Any ideas?

2000 F250 V10 & auto

Since you replaced all the coils ($$$!!!), I've gotta lean toward it being the coil boots.

This happened to me on my '02 V10; I was changing my plugs and I thought I had a bad coil. I bought a new one, swapped it around the engine for each old coil but the miss was still there. Thought it was something more so I finished up the job, and installed new boots, siliconed the living shit out of everything. Miss was gone! This has happened to others too; it's the boots rather than the COPS.

I'm going over my head here, but I remember reading, the OBDII system on our trucks won't throw a code or check engine light for misfires.

Good luck, hope it helped!

I bought 4 new coils. 2 of the old coils had torn boots, so I replaced those first. Then switched the other 2 around the motor to see if any others were bad. I cleaned and siliconed all the stock boots while I was in there. still nothing.

I looked around for boots, but none of the local parts stores carry them, just the COPs... did you get the boots from a stealership?

Someone else suggested the PCV hose may have a leak. I replaced the PCV, but didn't check the hose- I guess that's next on the list too.

Yes you can get the boots at Ford dealer, funny you call it a stealership when they have the parts you need and can save you some $$ over buying the complete COP unit. There is a vacuum hose at the throttle body that will .get oil soaked and this will degrade the rubber causing a leak. I do know there are a lot of crappy dealerships out there but I get tired of all of them being called stealerships:mad3: The dealership I work at woud have charged you $100-$150 to diag the problem and then we would have fixed it with out the waste of throwing parts at the problem

x2 on the boots. We have a number of v-10's at work and when they start to run a little rough 9 times out of 10 it is a coil boot.

I do know there are a lot of crappy dealerships out there but I get tired of all of them being called stealerships:mad3: The dealership I work at woud have charged you $100-$150 to diag the problem and then we would have fixed it with out the waste of throwing parts at the problem

No offense, but many years of bad experience with dealers from Mass, to Florida and back!! I talked to the local Ford dealer about this- $180 to get me in next week and run a full diagnostic that a local shop did for free last night. No codes either way... only showed the intermittent missfire. Parts cost more $ and then minimum of 1 hour of labor to do any minor jobs. I have known and heard about alot of dealers throwing parts at problems too... thanks for the help just the same.

I figure right now I am out the 2 additional COPs ($100) as 2 of them looked to be in bad shape (corrosion on the connections, torn boots etc).

Got some new boots, $15 per pair at the local parts store- they call them spark plug wires for some stupid reason... I also plan to take a look at the PCV vacuum hose.

I just don't have time for this- I close on my new house in a week and need the truck to move my junk!

Thanks again!
TD

Sent you a PM about the boots before I read the post again...guess you found them! Good luck with the problem. :smokin:

I feel your pain, I'm trying to get a house ready to go on the market. Of course I'm taking a week long trip next week across death valley and the Mojave road, the wifes real imporessed about that:D

I'm going over my head here, but I remember reading, the OBDII system on our trucks won't throw a code or check engine light for misfires.

My '01 F150 with the 5.4 had problems with the coils. It never threw a code until a coil went completely dead...it just ran like shit. I finally got tired of messing with it and swapped out the remaining 7.

The chain shops were useless unless it threw a code.