[rysess20]

I have a 2002 Jeep Wrangler Sahara 4.0, AUTO, 118,000 miles to give you vehicle info. I have had the vehicle since April and have only put about 2200 miles on it. It sat most of the summer due to awesome weather in Upstate NY. Anyways I started driving it a little so it did not sit any longer and I developed a little skip only at idle. As soon as you hit the gas it was smooth and fine. I went through a couple tanks of gas and the check engine light came on. I head to Autozone and they got a Cyl 2 misfire. I read many posts and decided to go to Walmart and grab the APP985 as they seemed to have the best result and now when I gas it and get up to speed it pops every so often and the skip at idle is worse? The plugs must have been new when I purchased it because they had almost no sign of wear. I have put a thing of fuel injection cleaner through at every tank hoping the little skip would go away and it didn't. Any suggestions?

Thanks

Ryan

[FedEazel]

Maybe check the other little things, air and fuel filters, etc.

The 4.0 isn't the smoothest idling engine on the planet, though.

[Imped]

How's the throttle body? If's probably all nasty so clean it out. If that doesn't do, it I'd suggest going out on the highway and running the jeep through its revs a bit. Letting it sit and driving it easy isn't the best thing to do. Go beat the piss out of it for a while and see what happens.

[rysess20]

The 4.0 is def not the smoothest engine going but its throwing a code and I am trying to sell it due to lack of use. I hate to spend 130 bucks on a coil pack, I looked into the throttle body and there was only a very small amount of black but I will go back and try cleaning that. Thanks I hope there are some more responses but beating the hell out of it at this point seems like a fun one to try, lol.

[KilgoreTrout]

Did you check your spark plug gapping? Don't know what the FSM says off hand, but I believe it's .035 to .040. If the only thing you changed was the spark plugs and the symptom got worse, chances are it has something to do with the spark plugs. Double check the gaps, their seating, torque, and the top rail. If you still have the old spark plugs, try reading them to help diagnose the problem. NGK Spark Plugs USA

[Bubba3200]

Try taking out the sensor's out of the throttle body and cleaning them also???????

[Zen]

Also... I haven't used the Autolites, but check to see if the ends of the plugs are screwed on tight and add some dielectric grease.

TSB 18-31-97 calls for the use of Mopar Combustion Chamber Cleaner to help alievieate misfire DTCs on the Jeep 4.0L

Mopar Combustion Chamber Cleaner/Conditioner is really good for removing
carbon deposits...The following directions outline the way that professional
mechanics have been using the cleaner for years -- they were finally
published in TSB 18-31-97 for 1996-98 Jeep 4.0 Liter misfire conditions:

1.. Operate the vehicle until the vehicle reaches operating temperature.
2.. Remove the air tube from the throttle body.
3.. With the engine at an idle, spray the entire contents of Mopar
Combustion Cleaner, p/n 04318001, directly into the throttle body. Allow the
vehicle to load up with the cleaner to the point of almost stalling out.
4.. Shut the engine OFF after the entire can is ingested.
5.. With the hood closed and the vehicle parked inside the garage, allow
the vehicle to soak for two to three hours. This will ensure that the engine
will maintain its temperature and will allow proper solvent penetration.
6.. Drive the vehicle on a highway/freeway that will allow the vehicle to
be driven safely at the posted speed limit. Upon entering the
highway/freeway, accelerate hard to the posted speed limit and maintain
speed. Slow down and then perform 5 to 10 Wide Open Throttle (WOT) upshifts.
Continue driving at the maximum speed limit for 1-2 miles (if conditions
allow).

[-dirt-]

Be sure to confirm that you picked up the double platinum APP985 plugs, not the AP985 plugs.

My local Walmarts only carry the single-platinum (AP985) plugs...

[93jeepyj]

I'd try running a regular champion copper truck plug in it, if the plugs made it worse thats what id change first. My fathers 01 xj had a misfire issue for a year before we realized it didnt like platinum plugs. The misfire isue went completely away after putting in plain old truck plugs.

[gmaus]

How about you check the plug wires. Then check the Coil pack for the cylinder. If it is one cylinder and the plugs don't look worn or fowled it probably isn't the plugs.

[mrblaine]

Originally Posted by gmaus

How about you check the plug wires. Then check the Coil pack for the cylinder. If it is one cylinder and the plugs don't look worn or fowled it probably isn't the plugs.

I've never heard of birds getting to your plugs before. Must be a regional thing.

[Jerry Bransford]

Check that you got the coil rail reinstalled properly. If the plugs you installed are the APP985 and not the AP985, that's an excellent plug choice and would not be the source of this problem.

[gmaus]

I've never heard of birds getting to your plugs before. Must be a regional thing.

Sorry mrblain I just can't spell I guess. I was just trying to get the op to look at the rest of the ignition system not the plugs. I don't believe bad coils throw and code besides a missfire.

[TheBoogieman]

Originally Posted by gmaus

How about you check the plug wires. Then check the Coil pack for the cylinder. If it is one cylinder and the plugs don't look worn or fowled it probably isn't the plugs.

What are plug wires?

[TheBoogieman]

Originally Posted by gmaus

Sorry mrblain I just can't spell I guess. I was just trying to get the op to look at the rest of the ignition system not the plugs. I don't believe bad coils throw and code besides a missfire.

It's mrblaine and fouled and misfire.