Try posting a link that works, thanks.

yeah you could have said something about it not working alittle nicer then that... if he knew it didnt work then im sure he would have fixed it... relax...

Hey no problem guys. I got this jeep and I'm in it for life! And in case the facebook photo didn't work here's a photobucket link.

http://s904.photobucket.com/albums/a...firesolved.jpg

Don't we all wish we could predict things... LMFAO

It wasn't meant to be sarcastic, but after reading it I guess it could have been taken that way.

no worries... typing doesnt tell the whole story...

XJ1997,

Here's a photo of my wiring harness:



Your discription matches my symptoms, yet in looking at the harness, I can't see any place for the nick your photo shows. Please look and comment.

Thanks, I've been chasing this for 2-years.

any engine codes?

I had a persistant problem with #3 misfire. Since it's a '97, Heat Soak probably isn't the problem (99+).

I replaced #3 injector and all of the O-Rings on the other injectors. During the install I noticed that the new injector slid in the recess of the manifold much easier (too easy) than the other injectors.

I haven't had any codes but recently I decided to replace my Bosch plugs with Champion Copper Plus and notice that #3 plug insulator was white and the others were as they should be (tan to light brown), this tells me that there is still a very lean mixture at the #3 cylinder. I believe that when the engine gets hot and the manifold expands it allow air to leak past the O-Ring at #3 causing the lean mixture.

You might want to pull #3 plug and see what it looks like and compare it to the other plug insulators. These engines are set to run lean for emissions and won't tolerate leaks very well...just a thought.

Turns out XJ1997's post got me on the right track. Today it was sunny and warm enough to back the Cherokee out of the garage and have a look. The valve cover had nothing to do with the problem, rather the fuel manifold was the source of the problem.

The fuel manifold is ~24" long x 3/4" Dia steel tube. The tube has welded caps at each end and six spigots, one for each cylinder injector. The welded cap ends are very sharp and if the cable harness gets wedged between the fuel manifold and the firewall, in time one or more wires will be grounded.

Here's my original photo and you can make out the manifold mushed into the wire harness:


This closeup makes it very clear:


Simply moving the wire harness from this pinched location eliminated my high speed misfire. However it did not eliminate the idle misfire. I suspect one or more spark plugs are badly fouled.

At least my Google search got me this far, very grateful. It's been several hundred dollars chasing idiot codes by "professional" jeep mechanics.

Thanks for coming back with the clear pic. It's not warm and sunny here now (-4 as we speak) but I will check mine soon. Although I'm not getting misfire codes I can still feel/hear a slight miss at idle. If you're thinking about changing plugs the general consensus that I’ve seen by monitoring four Jeep forums is that the 4.0L likes Champion Copper Plus plug (cheap) and their Truck Plugs. NGK V-Power is also high on the list and I believe that Chrysler recommended them as part of the fix for the 99+-heat soak issue.

I just put in Champion Copper Plus and indexed them. I noticed a slight improvement in drivability and idle over my Bosch single ground strap plugs. But, since I got a gift card for O’Reilly’s for Christmas I’m tempted to go with the NGK V-Power.

Ouch!!! It only gets below zero a few times a year here and I live at 8500 feet.

WOW!! WHo woulda Thunk it ??....Glad you got it !

However the first step in testing the injector is to listen to each one with a stetho or a Wooden stick held against the injector and the ear. You would likely have found that the #3 one would not have been "Clicking" like the others...Just an FYI /..

Glad you figured that out !

I just opened the hood to look at the spark plugs and the wiring harness was back snug against the fuel manifold. This was after a 10-mile drive for testing. So I wired the harness up and away from the manifold. It's possible this was the cause of my idle misfire. Next time I drive into town I'll know.

Sorry it took me a while to reply. You'll see the square black plastic sleeve that covers the injector wires and kinda acts like a loom just square. Where the wires come out of the back of that is where my entire problem spawned from.

There's a 3 or 4 inch ribbed loom over those wires and the head bolt actually did the rubbing... Specifically the white wire with yellow stripe that goes directly to the #3 cyl. Hope this helps...