I work at a service station with three mechanics; I am not one. I have had a 6th cylinder misfire for quite some time now. I have replaced the spark plugs, installed an Ignition Coil, and done a compression test; yet, it continues to misfire almost every time I drive more than 15-20 miles or so. Sometimes it misfires at random times but rarely. I love my Jeep, I have put almost a grand into it since I bought it. I have fixed everything except for this aggravating misfire. The mechanics at work all recommend that I do different things, but I would like to get the opinion of other Cherokee owners before I spend any more money.

 

Try swapping the injector with one from another cylinder, see if the misfire stays or follows.

Seems more than one oddball misfire problem with the newer 4.0's has been a bad valve spring too.

 

What year is your Jeep what motor does it have?

 

+1 to this advice. Definitely eliminate the usual suspects first (plug, plug wire, injector). Mine was due to the valve springs, as mentioned. The valve spring TSB applies to '96-'99 4.0 engines.

 

its pretty hard to give advice when you do not know that year or motor of the jeep.. sorry tp say... you can't always assume its a 4.0...

 

It says 2000 near his avatar.

Try this. Worked on my friend's 99 after everything else failed, including valve springs.


Pretty easy.
Get a cup of water, preferably something like a Dixie cup.
With the air cleaner off, hold the engine RPM at 2000 RPM or higher and dribble the water from the Dixie cup, which you've pinched to look like a spout on top, into the carb or throttle body. Go slowly and the engine will bog a bit. Stop and let it recover. Repeat until the cup is empty.

 

dang i miss that...

 

It's usually ME doing that. Thanks for the company.

 

Right, that's why I specified that it applies to '96-'99 4.0s.

 

It is a 2000 Jeep Cherokee Sport, straight 6, 4.0L

 

So,if it only applies to '96-'99 Jeeps, my 2000 shouldn't have a valve spring issue should it?

 

Maybe not. But, it could have the carbon under the valve issue and need the water treatment to remove it.

 

Ok, thanks