hey guys, Im the 6th owner of my XJ and from the way it looks no one ever properly maintained it so i recently replaced my spark plugs, wires, distributer cap and router, i made sure that all wires were in the correct spot on the cap, then i went ahead and started replacing the plugs and i found that none were gapped the same, they ranged from .040-.055, i made sure i gapped all mine at .035, so anyways after everything was properly installed i went to start her up and the whole jeep started shaking, when i rev the engine it smoothes out a little but still can tell its not running right,

my only thought was that maybe the computer was compensating for the old plugs that weren't properly gapped and once i replaced them, the computer compensations were causing the shake...

 

What year is your XJ and what types of plugs did you get? From what I've read on this site, it seems like the 4.0 can get very finnicky when it comes to plugs.

 

i have a 99 sport and i put Autolite copper core plugs in,

 

Is the firing order right?

 

Best plugs to get are Champion Coppers. For some reason the 4.0's tend to like them the best. Make sure all the plugs are fully set as well as the wires. Also, make sure you've got all your wires are plugged to the cap correctly as well as to the proper wires. Never hurts to double check.

 

i made sure all the wires went right where they were on the old cap so i would assume so

 

Are they torqued down correctly? And are all your wires on tight on both the cap and the plugs?

 

i had my grandfather helping me and he's a mechanic and he double checked if they were all torqued down properly and i just double checked the wires

 

153624, clockwise from 5:00 viewed from the side. Worth double checking..anyway.

 

ok we just checked the wires and started it again and now the check engine light is flashing on and off

 

ok ill check that

 

Did you check to see of any of the plugs are cracked? Sounds stupid but I have seen it happen. Look under your hood, it should tell you the Champion spark plug number. Use the champions. One last thing. You said the previous owners did not maintain the vehicle, did you blow out the spark plug hole area with the spark plugs still in the motor? If you got dirt, mud, and what ever stuff which can accumulate around the spark plug holes in the motor that could explain your issues as well.

 

no we didnt blow out the holes and all the plugs looked fine but ill check in a few

 

You said the CEL was flashing on and off do you have a computer handy to check out the codes?

 

no i currently dont my dad has a freind coming over tomorow and he owns one, he could probably bring his