joes99xj

It seems like this jeep is cursed with repeat codes for miss fires evap fuel you name it Im always chasing codes. But its the crap that dosent throw a code and engine dosent want to start or runs rough for a while. I have replaced single coil pack but it seems like another needs replacing. So are there any good options.

lualchro

I own a 2000 XJ 4.0 with coil pack as well.
In my case I was able to feel or listen to a misfire in idle, and the lack of power on the jeep was noticeable.
Pulled the Coil pack from the head, installed spark plugs on the air and lean the threads of the spark plugs towards the valve cover, while had an assistant trying to start the Jeep, one of the spark plugs never got spark, change them around and same thing.
After searching for information I was able to see that the coil pack is made from three different coils, and it is what they called "Waste Spark System" meaning the coils are set to send spark to two plugs at the time, one in the compresion stroke and the other one on the exhaust stroke, one of the lines from the coil to cylinder 5 was broken inside the coil pack.
In short, I looked online for a replacement, and found on ebay a good deal, backed up from a reputable seller with 10 years warranty on the part, no need to look forward, ordered it and the Jeep has been running strong since.
Also I did have the code for the missfire
not sure if this is your case but you can follow the method for testing that you have good spark on all cylinders