Brandenfwee

Hey I'm new to the forum. Wanted to get started right away and see if I can get this problem taken care of. Ok, 98 Cherokee 4.0, started running a bit rough on me last week. Check engine light popped on so I had it read and it's a cylinder 1 misfire. I was On a budget so I just changed plugs first, still misfiring. Then wires, still misfiring. So then yesterday I changed distributor cap and rotor button. And again, still running rough. Took it back to advance auto parts to see if anymore codes had appeared and it's still just cylinder 1 misfire. So, I don't know if it'd be related or not but the radiator cracked and she overheated once about a month and a half ago She was shutdown and I replaced radiator and thermostat. I do know that the catalytic converter is rattling like crazy, has been for some time, but it's never really affected anything so I've been putting it off. Could anyone tell me what else can be done to get her running right again? She's fine once up to speed, but idling in park she's ehhh ok, but not good ya know? And once shifted into drive/reverse, she's very hesitant and violently shaking, and I can hear the cat underneath me through the floorboards it's so damn loud. Any advice would be greatly appreciated. Thanks.

tjwalker

Welcome to the forum!

For a single cylinder misfire, I always approach it in this order:

1. Plugs (you did that)
2. Plug wires (you did that)
3. Distributor cap (you did that)
4. Fuel injector.
5. Internal condition of that cylinder

So concentrate on the fuel injector circuit and the internal condition of that cylinder. I usually swap the injector on the suspect cylinder with a different cylinder to see if the misfire follows. If it does, you have smoking gun proof of a bad injector. You also should verify that you have an actual PULSE going TO the injector. Without that pulse, the injector will absolutely not fire. A "noid light" is a good tool for this job.

If fuel injector and fuel injector PULSE checks out, then it's time for you to perform a compression test on all cylinders and see how cylinder #1 matches up. For the 4.0, you're looking for a 120-150 psi, with no more than a 30 psi variation between cylinders.

Good luck and keep us updated!

Brandenfwee

Thanks, I'll definitely swap the injector with another tomorrow and post the results.

Brandenfwee

Ok. Someone got me a fuel injector for a fathers day gift (weird) so I thought it wouldn't hurt to just go ahead and replace cylinder 1 with it. Still misfiring. Going to get compression test done soon so I'll post again when I get results.

Brandenfwee

Ok, so had compression test done this morning. All cylinders were in the 140s except for cylinder one which was less than 10. So I suppose best thing to do from here is to check out the valves? She's running at the moment, pretty crappy, but getting me from a to b. so I don't want to get so far taking her apart the point that I can't drive her the next day. So I guess what I'm asking is, is what all do I need to check out the valves (if that's the problem)? What special tools would be required? Etc

tjwalker

Another thing you need to do. Introduce a tablespoon of oil into the cylinder with low compression.

Then re-run the compression test in that cylinder.

If the compression comes up with the oil in there, you likely have a ring problem. If compression stays the same, you likely have a head problem.