Cylinder missfires need help

[riverrat62]

I have a 2005 Liberty. Check engine light came on, took it to Auto Zone had them hook up there code checker. Came up missfire cylinder 2. I had this problem 2 months ago and replaced spark plugs and it took care of problem, now its back. Guy at Auto Zone told me I needed to replace spark plugs or plug wires. My question is can I replace the wires, how hard is this? Or should I try replacing coil packs. Any other suggestions?
Thank you for any help.

 

[Snail Farmer]

Your Jeep doesn't have plug wires like he's referring to. It would be the coil pack itself. I would swap the #2 coil pack with another one, and see if the code follows the coil pack or not. And you don't need AutoZone to pull the codes for you, the Jeep will tell you the codes. Get in and close the driver's door. Turn the key to the on position without starting it. Then to the off position, then on, off, on. After the third time you switch it to the on position, any codes will be displayed where the odometer is.

 

[spideyrdr]

I had a similar misfire code last year after we rearended someone doing a U-turn on the interstate. Got it back from the repair shop and a few days later the code for misfire in cylinder 5 showed up (I have a cheap OBD scanner so knew what it was - but I didn't know about the on,off,on,off,on,off trick so thank for that).

Turned out there was a little moisture under the seal in the #5 coil pack. Check to see if you have some moisture in there - if it went away after changing the plugs, you might have dried it out during the change and now there is moisture again. The seal in the coil might be bad. Or the coil might be bad. Snail Farmer's right, you don't change the plug wires on these like you might on a non-coil setup, so hopefully that's not the problem.

Edit: Once I removed the coil and let everything dry overnight, it fixed my issue. Should have put that in the post, sorry.

 

[riverrat62]

Thanks guys. I never thought of switching coil packs, and I use similar technique to troubleshoot machines at work. I didn't think the wires were the problem with coil packs right on plugs, but this is my first vehicle with this setup. Will try it tomorrow and let you know what I come up with. Moisture deal makes sense too, will look into that also.
Thanks again for your help

 

[riverrat62]

Finally got some time off to work on my jeep. Switched coil packs between two cylinders. Check engine light went off, has not come back on. Hopefully that takes care of problem. Thanks for all your help.