XJowner96

Was driving my XJ last week and had a miss show up. No sign of problems before this, with a tune up done in April (plugs, wires, distributor cap, button, oil change). Ran good after this until last week. Almost like it is jumping spark. Worked through the wires, changed the plug thinking it fouled, but still no change. No service engine light, no codes when scanned (have a buddy who is a mechanic and has a garage-worthy scanner).

Did a compression test and all cylinders good except for #1 with 90, 150 in the rest. Tried the oil trick and no change. It only idles rough with hesitation/sputtering intermittently when driving. Any ideas? Burned valve? Bad distributor? Sensor? Also have noticed a clicking in the distributor? Never had this before or dealt with anything like that before.

This is my daily driver and I need to get it fixed, pronto! Driving the gas guzzler right now (V10 Ford) with really no other choice to until I get this one fixed. First Jeep and I love it, wanna keep it. Kinda frustrated since I am normally good about figuring this stuff out. Help!

wizardpc

Have you pulled off the distributor and checked the points on it and the rotor?

XJowner96

Yep. Went through all the things you think of first like that. Never know, sometimes you get a bad part, but like I said, everything was fine until that miss showed up. Changed the plug even, thinking it had fouled but was okay. Messed with the wiring and such for the injector and no change, messed with plug wires with still no change. Just do not know what to think right now or what else I can possibly look at.

Larry's XJ

Have you narrowed it down to one cylinder? Last time it had a full, complete tune-up? Can't remember what is on throttle body that needs cleaning. Check fuel pressure ??

Larry's XJ

What do you mean by points?? Automobiles stopped using points in the mid-late 70s

Larry's XJ

Throttle position sensor

wizardpc

I'm pretty sure he got my meaning.

XJowner96

Thank you for your replies. We have narrowed the misfire or issue down to cylinder 1. Have checked for vacuum leaks, worked through the parts used for tune-up. Looked under the dist cap and checked everything under that (you are right about points, I just did not put the reminder you did) and everything seems fine under there...no moisture, no issue that I can find. I had thought maybe cam or crank position sensors since they are common issues, maybe even a stuck valve or burned valve. Have never seen a picture like this before...and been working on or around cars since before 15 years old so seen my fair share, including a Mustang with points and condenser (1973).

With no DTCs and this mixed picture, I am at a loss as to where to start. Guess I will try cleaning the TPS and see where that gets me. Cant hurt, and honestly something that had not crossed my mind. Been busy as heck and running around like crazy!

XJowner96

Wizardpc, wrong hardware sweetie. I am not a he. And yes, I understood perfectly what you meant. No harm, no foul. Its all good.

teamarctic

You need a leak down gauage to figure out where your compression is going. 90 is to low. Easy check if you have an air compressor is, put it at top dead center #1, use your compression testor fitting and hook up the air fitting and listen to where the air is going. Throttle body or exhaust indicates valve issue, dipstick tube indicates ring/piston/bore issue.

Waynerd

Leak down test it for sure. Mine is at 120psi compression and still misfiring. Leak down tested it only gets to 10psi and won't go any higher. Not sure if it's valve spring or valve yet. Also one of my other jeeps had a bad spark plug and it skipped very bad almost not drivable. It somehow never even lit the CEL so just because the CEL isn't on doesn't mean much. I