We've been running the Appalachian Byway and my 08 JKUR had been perfect. Coming off the trail, it suddenly began to run roughly and the check engine light flashed. We checked the code and it was one for a cylinder misfire. We drove it to Ashville, NC, and found a hotel across from Fields Jeep dealership. We went over to Autozone and I picked up new spark plugs and wires to install and eliminate them as the problem. Unfortunately. it did not work.

I'm not a mechanic, but I'd imagine it could be a bad injector, or a valve issue? Anyone have any guesses? Coil Pack? There appears to be a very slight tick, but it disapears with rpms. My gut tells me it is not a valve issue.

Anyone else have the coil pack fail? What did the symptoms feel/sound like?

I'm hoping it can be fixed in a reasonable amount of time. It is under the lifetime powertrain warranty, so that's good. Hopefully the dealership will get right to a transient customer. I had one in KC do that, replacing the slave cylinder and getting me on the road in about 2.5 hours.

If it is the coil pack, I'm guessing that probably is not under warranty. I'm wondering what they'll charge if that is the issue?

 

Sorry to hear that she's not running up to par. As I recall, you've got a few miles on her so the coil pack may be due. As as plugs and wires- I'm surprised that didn't cure it. With it going away at higher RPM's, have you tried putting a little higher grade fuel in it to see if that helps?

I think the price on the coil pack was $50-60 when I was looking not so long ago and labor is two screws and 6 wires....probably a plug as well for main power. I can't imagine they'd be too rough on you.

 

We did the plugs and wires last night. The old ones were in very good shape. The plugs only had about 40k on them, so I expected they'd be ok unless there was a big problem. I actually had a new set at home because I normally change them at 40k when the gaps start to widen a little and I would get a little ping. This set, however, wasn't pinging and it was running like new, so I left them in. I checked gaps on the old ones last night and they were almost perfect.

The only thing is I wish I'd done the coil last night. I'm betting that's it. But if it is an injector, they'll take care of that and I think it will be under warranty.

I'm really hoping it is the coil. I thought about getting the coil and doing it before going to the dealer, but I wanted to play it safe and be first in line. I'll kick myself a little if it is the coil. But I'll be happy because we'll be back on the trail.

I'll post up what they find.

 

Oh yeah, we also put a tank of Exxon premium and a bottle of Chevron Techron in there, just in case, LOL!

 

When I got P00300 and P00302 it was the fuel injectors went bad.

 

Good news. It was just the coil. The dealership took care of it and checked for any damage, as we had driven about 60 miles on the misfire. They said it was in good shape. So we're back on the trail tomorrow! My brother drove it back from the dealership and said that it felt great. I wish I'd thought of the coil pack last night, but oh well. I'm just glad it wasn't something worse due to time constraints and distance from home. It is also good that the plugs and wires are now new, so there's that, too. Lol!

 

That is awesome news. You'll have to have him check the mileage and see if it comes back up. I'm sure I'm due for a coil, I just haven't gotten there yet.

 

We'll know pretty quickly when we hit the road back to the trail tomorrow. It dropped to 13.7mpg with the misfire. I'll report back after the day on the trail.

 

I forgot to update you. The mileage came right back. I've been driving it to work this week and confirmed that it is at least as good as it was before on my regular commute. The engine continues to run like new!

 

Maybe I should bite the bullet and get the coil pack ordered then, I mean....this factory one has been with me for 260k miles now and they've not been easy miles. I could get that and the plugs/ wires swapped out at the same time.