94 xj Died, knocked, now ok. Ideas?

I've gotten a lot of good info. from all of the posts I've read. I had planned on contributing a write up in the near future as my first post. You know, best laid plans... etc. just didn't work out that way. Sooo, Right now however, I've got a stumper.

I was on my way to get a haircut last week when all of a sudden the engine died, like I had turned the key off. Got gas? Yup. Alternator/battery ok? Yup. It normally starts right up. 1st crank: tries to start but doesn't. 2nd time: Starts but seems to only be running on 4 or 5 cylinders and has a low knock. I'm thinking rod knock... just great. I'm only a block away from supercuts so off I go, chug chug knock knock into the parking lot. Heck, at least I'll look good when the tow truck arrives! :thumbup:. Anyway, I come out after getting my ears lowered, and she fires right up, running on all 6. The knock is still there, but it's not quite so bad now, so I decide to drive it the 6 blocks back home. Long story short (er), over the last 3-4 days the knock has completely disapeared and the car is running as good as it ever has.

Now I'm leaning toward some sort of electrical problem, causing power loss and a pre-ignition knock? It's really bothering me since the last thing I need is to get stuck in the outback of Death Valley. Then again. it's hard to fix something that, right now, isn't broke. Any ideas as to where to start diagnosis-wise?
Cheers to you all! :cheers:

SC

Wow, you're lucky!
My best guess would be that you had a temporary, self fixing, fuel quality issue. Perhaps you had some water in the gas - was the tank very low, or have you had many drastic temp changes causes condensation build-up in your fuel tank? If that had happened to my, I would use a double dose of the Techron fuel system cleaner and then a strong dose of Heet, then change the fuel filter out after running this mix for a tank.
Good luck,
Adam

Gas was low. I had about an 1/8 of a tank. The night before I did an 80 mile round trip to LAX. Could have been water or condensation. We've had Santa Ana winds and lots of wild fires here lately.

I had similar issue years ago with a 2.5l '94 cherokee, except mine didn't clear up for quite some time. I parked it behind the shop i worked at and tinkered with it in my spare time over the course of 2 or 3 months. Several of the techs i worked with looked at it and none of us could agree on exactly what it was. Mine had a knocking noise from the top end. Thought it might be a cracked valve spring so i pulled all out and checked them-all fine. Only thing I found was abnormally high oil pressure-like 80 spi cold. Did a quick oil change on it and within 10 minutes of changing the oil it cleared up. Drove it for another 20k with no problems.

Did you check for codes? Not that that is always useful, but an electrical problem that bad should have set a code. Otherwise, I'd be inclined to think it was something mechanical or fuel related, which don't show up on OBD. Perhaps a piece of junk got into a lifter and caused it to collapse for a while, or an injector misbehaved, or as suggested above, maybe something in the fuel.

If you haven't yet, you probably should do an oil change just as a precaution.

All sounds like good advise. Will do an oil change and run some cleaner through the fuel system and do a filter change. No codes showed up and check engine light never came on. It's still running tip top. Just puzzled me.
Thanks for the help!

SC