My 2000 XJ is miss firing cylinder 3&4. Just changed the plugs yesterday. Jeep has 186,000 miles on the motor.

Running a little rough prior to the new plugs, but now the check engine light is on.

Is there a way to test if the ignition pack is going bad? Or is this something that I should replace because it's getting old?

-going to check the gap tonight on the plugs

What else should I check?

Thanks,
Stitch

 

Are you sure the ignition wires are on correctly? If wire 3 is connected to plug 4 and wire 4 is connected to plug 3 it's not going to run smooth.

I'd check the firing order and make sure it is all connected right. FWIW, I made that mistake on my 82 Ford Granada straight 6, it ran but it ran like $hi+.

 

nvm

 

Update:

Removed spark plugs in the 3&4 cylinders. One of the plugs was bent like it was dropped. Should have caught this prior!

Then, I unplugged the coil and plugged it back in.
Placed it back onto the plugs and cleared the computer and fired it up. Engine light stayed off.

Good to go!
Thanks,
Stitch