Originally Posted by itscakes
Just make sure everything sits perfect if the coils aren't inserted 100% correctly it will cause a misfire or rough idle. Pretty simple to do. I would add a little bit of electrical grease to the plugs as well when installing.
ITSCAKES - Ditto "100%". My TJ was throwing codes for cylinder 1 and 2 and multiple cylinders and I could tell it was misfiring. I swapped back to OEM plugs and it wouldn't even run. I simply took the ignition rail off and reset it and it runs perfectly and no codes for a month now.