I know, there are tons of these already, but hopefully I can add a little something.

99 f250 v10 has a rough idle, gets worse under load (low rpms) smooths out over 2k and still pulls fine once it gets past the rough patch. I knew I needed plugs (117000mi) but after all I've read on here I was a bit nervous to say the least. I've been wrenching a decent amount of time, 20years, and figured most of the worry was about the aluminium heads. Ive been messing with Datsuns (aluminium heads)for years so sunday I went for it.
Not saying it was fun, but 3.5hrs later (and 95deg out) I was done. It really wasnt that bad. No issues other than getting to the back passenger plug.

Now the truck runs a little better, but still has that bad miss. While the coils were off I ohm'd them all and they were within .01 of each other. Seems good. All the connectors look good. All the boots are good, no cracks and pliable. Springs all look like knew.
Still no codes either.

Yesterday I inspected all the egr system and its fine. I got a couple known good (and new) coils from a friend and started swapping them 2 at a time hopping something would at least act or sound different. No change, no codes. I was frustrated so i disconnected 3 coils and started it. That was very easy to hear and feel, plus instantly through a code for all three. Hooked them up, cleared the codes, went for a drive. Still running rough, still no codes.

When I pulled the plugs they were all worn, and looked like it was running lean. Tomorrow Im going to reinspect all the vac lines, and ohm out all the sensors I can scrounge up info on. Everything acts like all the other posters Ive read solved by knew coils. Im about ready to just buy a conplete set of the cheap ebay ones, then if it clears up get a nice set and keep them for spares.

Any other ideas? A friend was telling me to get a hold of a scanner, not code reader, that reads live data. I guess it would show intermittant misses that are enough to effect it, but not bad enough to trigger a code. Sounds like a good idea to me.

If anyone has ideas, suggestions, comments, questions, or mockery feel free to let me have it. If you know a particular thread with good info or troubleshooting links that would be great too. Thanks either way, Brian

 

Been there, no codes, sucks! I put a set of accell coils on my 99 when I bought it because it had a couple bad and they were cheap. Several of those have failed.... last couple times I just bought one new motorcraft coil and worked my way around till I found it.

 

I don't know if you've heard of an app for your phone called Torque. You buy a Bluetooth obd2 plug in and can scan and reset with your phone using the free version. A friend has the full $5 app and it can see live mode $6 data! I'm showing 3000 misses on #2 cyl. I'm downloading the full app and going for a drive later to see if I can get anything else to give out some info. Hopefully it narrows this down a bit! I'll post findings...

 

When you installed the Accel coils were they running well?
When they failed what actually failed - the coil, boot or spring?
When the Motorcraft coil fixed the problem was just the coil replaced or the entire COP?
Accel coils I've used in the past usually output higher voltage which would make it harder for the boot to contain the arc.
If entire COPs were changed did you try the Accel coil on another boot/spring?

 

Yep, I got that app and plug a while back, it's pretty useful.

Let us know what happens after your drive. I suspect you might have a bad injector on #2. Did you check the injector plugs yet?

 

I ran through everything and 1st thing is 2500+ misfires on #3, none on the rest. There's the 1st step. Also got a set of new boots/springs. Putting these on tonight and we'll see how it goes.

Thanks for the interest.

 

Fixed it! On the way home I picked up a coil and set of boots. Quick install and the truck is running great! Still need to do my exhaust studs/gaskets, but at least it's running right.

If you haven't checked out the torque app you need to. It was great seeing all the engine data, even without a CEL. Made t/s simple.

-Brian

 

I installed a whole set of 10, truck came to me with a mis-match of oe and aftermarket coils of various ages along with random misfires. New accell coils fixed that. First coil to fail was maybe 6mo in.... actually used the spring and boot off it on one of the newer of the old coils since the accell stuff was still practically new. Second was maybe at a year or so.... think that one actually finally threw a code.... tried swapping boot and spring from new coil to verify and was definitely the coil. Last one it was 100+ out and humid as hell.... no code.... worked my way around the motor swapping with a new motorcraft till I found it, boot and spring looked fine but didn't mess with further. Just happy it was fixed lol