It was about 30 degrees (F) out this morning when I tried to start the jeep. (2000 XJ stock. Bought used in August. No known issues, regular maintenance. 1 prior owner.)

Jeep had sat overnight...and when I went to start it and let it warm up, engine light came on and really rough idle. I turned it off, went back inside and waited on Advance Auto to open. I got it to Advance...the CEL was blinking...not solid. (Yes I read the scary meaning of this.) They said Cyl 3 Misfire (No I didn't get the code. I'm new to this. Don't yell. )

So got new spark plugs...trying to get TO the spark plugs now...but cannot for the LIFE of me (or dad or fiance) get the coil rail off. Will. Not. Budge. Yes the bolts are off, came off pretty easy...but this sucker is STUCK in there. It will wiggle, but can't even get it to come up an inch.

So...I don't know if the new spark plug will help...will try coil packs after that...but I've read a lot about it being a heat soak misfire...I highly doubt that in below freezing temps I'm having that issue?

Battery is recently replaced, nothing else since I've had it though. (Ok a headlight but that's not important...)

All thoughts on possible solutions to both the rough idle/misfire and how the heck to get the rail off would be much appreciated.

 

Check and see if the #3 injector has come unplugged?
Otherwise you are looking in the right direction, plug,wires,coil???

 

Well replaced all the spark plugs. No change. Coil packs next?

Can't detach the coil rail. Red tab is gone and it's almost impossible to see what is preventing it from coming apart even using a mirror.

Ugh. Can't decide if I should risk driving it back to advance to recheck computer codes or just replace more stuff and hope for the best. The flashing CEL scares the crap out of me. Plus she really doesn't like going over 45. Bad misfiring.

Any suggestions welcome. I've read a ton of threads about this issue but with it not being a heat issue I'm not sure.

 

OH!!! Forgot. When we finally got the rail loose the boot came detached from the spring in the #3 boot. Could the loose spring still be causing the misfire? It was pretty stretched out. Replace the whole rail maybe??

 

You have the 0331 head, which is notorious for cracking between the #3 and #4 cylinders.

Remove the oil filler cap and look in there in that area to see if you see anything. I hope not.

 

I recently had the same problem... except it was cylinder 2 for me.

I recently rebuilt the engine and put in Dodge Neon fuel injectors. I bought a repair kit (included pre-filters and new o-rings). Cleaned/flushed them out with carb & choke cleaner. Did everything I could do for my junkyard injectors.

Anyways, there was a strong smell of raw fuel when I got the blinking check engine light. But, no leaks. I pulled the plugs and #2 was wet with fuel. The fuel injector was stuck wide open. Replaced fuel injector, cleared the code, and all was good again.

The coil pack isn't cheap. You can test the resistance between the towers. If you need to replace it I would look at getting a Dodge Viper Coil pack from RockAuto.com and a decent set of wires. Here's the post http://naxja.org/forum/showthread.php?t=1066869 It's on my list of things to do next. I hate the coil pack.

 

Same thing happened to me and it was the #3 and #4 fuel injectors. It took me forever to figure it out and it pretty much killed the pre-cat. Luckily, when I run on 89 octane fuel I dont get any codes for catalyst effiency. Check the wiring harnesses on the injectors. If you have the ability, remove them, clean them, and get new o-rings. Or just get a set of 784 injectors, people sell them all the time here or you can get them from the Dodge Neon and Stratus at the jy. I found out by accident that the Stratus has the 784 injectors, I went searching the jy for neons and didnt find a single one. So I decided to check the last dodge in the lot, it happened to be a Stratus and it had the same injectors.

 

Definitely check the oil for signs of coolant. It'll look like mud.

Right now your most obvious problem is ignition-related. I'd start by replacing the boots, the spring are included with the kit. Did you use OE-style copper spark plugs or fancy/useless make-a-Jeep-run-bad platinum stuff?

Flashing CEL is bad news. Considering the cost of the mini-cats I would avoid driving that thing as much as possible until you at least have a solid CEL . Basic code readers are pretty cheap, and very good to have for any OBD-II Jeep!