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jeeper435 · 02-15-2010, 06:21 PM

i have a 97 ZJ with the 4.0l. i got the trouble code checked at Auto Zone they said the #1 and #3 cylinders are misfiring... any ideas of what might be causing that?

jeeper435 · 02-15-2010, 06:24 PM

i checked for vacuum leaks and checked the cap n rotor... i changed the spark plugs about 4000 miles ago.

**muddeprived** · 02-15-2010, 06:37 PM

How about the plug wires?

Brutalxj · 02-15-2010, 07:03 PM

Just guessing but if you can get it checked agean if not wiers or plugs maybe your coil is on its way out oh or check the connection once I lost that rubber thing and the connection was messed up.

jeeper435 · 02-15-2010, 08:29 PM

i changed the plug wires bout 20K miles ago.. jus before it started misfiring, i got stuck in the snow and i had to push the motor pretty hard to get unstuck. im wondering if there could be some mechanical damage to the motor. i tried listening for any knockin noises and stuff like that. the auto zone guys were saying it could be low/high fuel pressure too.

Brutalxj · 02-15-2010, 09:09 PM

I'm not sure I buy that mostly cause I have never had that prob. That's why I asked if you could get it re tested. If it is a prob with fuel press it shouldn't be consistent. A injector prob would be. A coil prob may or may not be. I would get it re tested and just play with it. See when it dose it idle full, throtle, drive only, ext. Oh at idle wiggle some wires mainly to the coil wire. Anything else should have come up on the test I would think.

jeeper435 · 02-15-2010, 09:44 PM

it seems to only misfire when at idle..

Brutalxj · 02-15-2010, 10:11 PM

Coil and or wire is still a big pos. But you may have gummed up an o2 senser but that test should have picked it out. You can most times pull them out spray them with brake cleaner shake them. That loosens the carbon and make them register fine. My axle hits mine from time to time along with my oil pan but I doubt that's you. If it. Is the print out would have said so. My best guess is still that coil or the input wires to it but this is a guess without seeing it.

jeeper435 · 02-15-2010, 10:43 PM

how can you tell if the coil is bad? should i jus replace it and hope for the best? this ZJ is my everyday driver. would it be ok to keep driving it the way it is? F.Y.I. its got 220k miles.

Brutalxj · 02-15-2010, 11:14 PM

The number of miles means nothing to an I 6 if properly manit. If you drive it and it is more serious it could get worse even if it is just the coil it could leave you on the side of the road. It has happened to me. I would get a used known as good part and try it out first. I'm lucky and have a good friend who is my locale used parts depo. But if you don't have that then. Buy new and worst case you have a spair. But if time allows spend some more time with it. It could be things I have never had prob with t p s, m a p, I'm just speaking from what I have delt with.

**jfxj67** · 02-16-2010, 12:36 AM

Just found this link, hope it helps!
2001 missfire problem - JeepForum.com

Moose · 02-16-2010, 01:01 AM

I had a similar issue with mine actually, and it was just the spark plugs. I could tell the difference right after they were changed so hopefully it could be that. Spark plugs are cheap anyway, it wouldn't hurt to replace them first and then see if that helps.

jeeper435 · 02-16-2010, 10:09 PM

i checked the compression and fuel pressure today. they're OK. so all i can think is wrong is the injectors.

Brutalxj · 02-16-2010, 10:14 PM

Switch them around see what happens

jeeper435 · 02-18-2010, 09:09 PM

i put new injectors in and still have the same ol' misfire! now what?any ideas?