Misfire Cylinder #5

New to the site and Jeep world and looking for some input. I recently picked up a 99 XJ with the 4.0l in it. Approximately 155,000 miles on it. I bought it knowing it had the CEL on and misfire on cylinder 5. Plugs, cap, wires all did nothing. Ohm check on the injector was good as well as the fuel pressure. So today I pulled off the valve cover and the rocker/pushrod on #5 intake is loose. I can move them maybe a half inch up and down by hand. And when the engine is started it is not operational. Is this definitely a bad lifter? Could it just be hung up or is the head going to have to be removed and replace lifters? Is there something else causing the problem that I could be overlooking? Hoping its not too major. Thanks for any insight.

You could have a bad lifter or the cam lobe could be rounded off. That can be determined by forcing the lifter down, while turning the cam and measuring how much lift is there. If the lift is fine, then the problem is the lifter.

Maybe this is a dumb question, but if there was a lobe worn on the cam would I still see movement on the push rod, just not as much as needed? A bit of a novice so I'm just trying to understand a bit better. I did, with the engine running, slightly pushed down on the rocker on the lifter side. It was making contact with something, lifter not traveling as far as it should? I also noticed there wasnt nearly as much oil traveling up on that rocker as the rest of them. Again, just a noob trying to understand the whole process. Thanks!

Yes, cam lobe can be partially worn.

Like old man said, you can hold the rocker down toward the cam and have someone rotate the engine. If rocker moves as far as the other rockers, the lifter is the problem (or maybe weird wear on the pushrod).

The lifter is supposed to pump up and remove the gap.

Either way, you have to pull the head. Just for jollies, pull the pushrod and look at it first. But odds on WAG is with a bad lifter, more than just one bad cam lobe.

Just to follow up ... I took of the head and pulled the lifters. The lifter was worn to the point that it had a hole in the bottom of it. With the lifter out, I was able to see some wear on the cam lobe as well. So, a new cam, new timing set, new lifters and a gasket set and cam break in additive as well. Everything seems good at this point, passed emissions and we are about a 1,000 miles in with no major problems to report. Thanks for the insight -ers. :cheers: