Hey, I am new here, but have been browsing the forum for quite some time now. I finally have a problem I can't figure or find a clean answer on the forum.
95 YJ 4cyl lots of miles, fairly rough truck, bought it really cheap a year or so ago.
Ran okay, other than a lot of ticking common for these older engines. The oil pressure consistantly reads low and has for the last year I have owned this jeep. Low meaning just above the peg at the bottom end of the gauge.
The jeep began to stumble and lose power one day when my daugher was out in it, at first just at stops, then progressively worse. It got so bad, she called me and pulled it over.
We drug it home and have since done the following:
Tune-up - plugs, wires, cap & rotor, air filter
Timing chain and gears
It continues to run VERY rough from the minute you start it and it never smoothes, I suspect 1 or 2 cylinders are not firing. If you try to drive it, 35 mph max maybe if you work at it, gassy smell under the hood, traces of smoke occassionally out of the exhaust. I pulled the new plugs, and 2 of the 4 (# 2 & 3) were already black and fouled.
It is not throwing any check engine lights, but that may be because it does not work or exist on this truck.
I have dealt with rough running on other jeeps, such as replacing IAC etc, but this is much rougher, shakes the heck out of the jeep.
Any wisdom, I suspect perhaps the engine is shot, but hoping for something less expensive.
Are you leaking oil anywhere? What kind of oil are you using? How many miles are on it? How long where the plugs in till they fouled out. That could be because you're running to rich. Are they oily or gassy smelling when you checked them? There could be a leak letting too much oil/gas in. Are your firing orders right?
I got some ideas but need some more info from you.
Thanks for the any help!
-No serious oil leaks (down less than 1/4 quart in 3000miles)
-Using valvoline high milage synthetic blend oil
-Mileage is ~ 156000
-New plugs were put in for the tuneup when this problem started, I did not get it running well, and pulled them when I changed the timing chain and gears, #2 & 3 were fould by then, less than 5 minutes of running. they were gassy smelling and black, not oily though.
-Firing order is correct from what I can see from the haynes manual, and we changed the plugs and wires one by one to try to avoid any mixup.
i would double check the timing... try running it in the dark, mine was behaving like that not too long ago. i changed the plugs out after i realized one of the plugs were shorting on the block. I imagine you may have a short somewhere in the distributor. try running it in the dark and see if you see any light coming from in or around the ignition system.
choke stuck? I don't know how these particular engines control their choke but man, sure sounds like way to much gas and that would be one way to get it.
Or, obstruction in the air intake such as a mouse nest??? Pull your air cleaner hose off from the throttle body and try it. If it smooths out, something is choking your air intake. ...just an idea of the first places I would check.
I would compression test each cylinder. Pull valve cover and watch movement on the rockers. You may have rounded off a few lobes on the cam and valves aren't opening fully on the two cylinders giving you issues. Good luck. Mine just hit 205k so I feel your pain.
Here is the update on what I tried last night.
1) I ran it in the dark, no visible ignition system shorts
2) I double checked the timing, first by find TDC on 1, then checking it against the rotor cap, they match, it is not 180 degrees off
3) Next I double checked the timing with a timing light, I am about 8 degree off of 0, it does move slightly, but it is roughly about 8 degrees off.
4) I pulled the air cleaner hose from the throttle body, it seemed to help slightly.
5) Following the lead that it may be struggling for air, I removed the elbow and hose that goes to the back top of the valve cover, no difference.
6) I removed that small hose that goes on the front drivers side just below the valve cover, something similar to a PCV valve if I understand it right. that seemed to improve things more, it smoothed out a bit. When I put my finger over the hose it bogged down heavily.
Is there something else I should consider and test? Could a bad coil cause this?
You cannot turn the distributor to change the timing so what electronically controls the timing? I read that the 1995 4 cylinder models don't have an ECM. Is there something else I should check there?
I need to try the compression test, I have never done that before and don't have a good understanding of that process. I will read up on that.
it could... I had it happen in a ranger. I had to pull each spark plug wire off with a glove until I found a cylinder that did not change the way it was running. That was my bum cylinder. It was bone dry inside and on the plug.
When that one was running it felt like sitting in a helicopter. It was horrible... new injector and away she went! Although, these may only have a fuel injected throttle body. Not sure that you have an injector at each cylinder?