97 Cherokee Oil Light??

[Isaac McShane]

I really appreciate all of your help, both Greg and Carnuck.

We did some trail riding last night, (about 4 hours worth). While driving into the trails, I lost my my power again, the engine started running real rough, and acted like it wanted to stall. This was before I went through any mud holes, and I left the a/c and blower off the entire time.

My buddy is now thinking it might have to do with the idle speed, perhaps injectors, and or computers :/

It never actually stalled out, and the power loss wasn't too bad. I kept on driving it, and aside from a few times when the engine sounded rough and the oil gauge was all over the place (a symptom of the primary issue) she ran really strong and mostly sounded good.

I'm not abandoning the idea of a siezing a/c pully, primarily due to the tin sound coming from it and the occasional belt squeal, but after last night when it happened without the a/c on I'm curious whether it's directly affecting the engine performance.

 

[greg92jeepxj]

Ok, let's not rush into a/c work just yet , I'm sure you want to diagnose once again after this power loss problem is solved. As long as the a/c is off , the compressor cannot engage .
It only engages , as you know in a/c mode and defrost. Even of the engine runs hot, the electric fan will not engage a/c. Wondering what state the idle air control motor is in but I'm thinking more now of the PCM . Not saying its bad but wondering if the plugs are secure. I guess so far your not getting DTC's ? It sounds like the engine is almost shutting down and maybe the drivetrain is keeping the engine rolling until the symptom disappears and runs strong again.
The loss of oil pressure is only because of the temporary stall. If it were auto trans , it probably would stall. This seems to be our problem more than a/c but we'll keep that on the back burner.
Dont want you to spend money on another PCM but wish there were one available to swap for diagnostic purposes. The connections ought to be checked as well. If idle speed and injectors are suspected , this would cause me to believe the fault is PCM related since they are driven by the PCM. But at this point I'm still not ready to condemn your PCM , the jeep runs well at least 90% of the time or even better. Loose connections or dirty grounds need to be checked. Computer and O2 grounds are usually found with the negative cable on the block but I cannot confirm on your year without seeing it or at least a diagram. My '92 does , maybe yours does to.
This is pointing toward electrical and that will be the next step in diagnostics , I feel.
Its safe to disconnect the battery when cleaning the PCM connections although some believe that's not necessary . I do it for safety sake. Any grounds and other connections you feel need cleaning that may contribute is worth a shot toward this and good practice in general .
Trry it when you can and see what effect it has. Once again , hoping for the best . Greg

 

[greg92jeepxj]

Something I forgot to mention , please check the wiring on the oil pressure sending unit switch again to ensure there is no short as that will cause fuel pump cut off . This is a safety feature if the truck were to be involved in an accident and the engine stalls but fuel pump is still running. Check this so it can be ruled out if ok.

 

[carnuck]

If the bearing in the AC clutch is going bad it can cause drag on the motor too. Maybe the noise you hear is a plug wire misfiring?

 

[Isaac McShane]

Well bad news, boys. My engine blew up. i was certain the problem earlier discussed was from the a/c compressor. I hadn't used it since earlier, and haven't had any more problems. I haven't even been doing much off roading lately. I was driving to the bank last week when I heard a long pop and a bunch of ticking, so I shut it off, we towed it home, I dropped the oil pan, and the piston rod was broken and missing. My buddy thinks now that the sound heard earlier was a bearing going out, and causing the engine to lag and affect multiple systems. I guess when the rod broke, it flew into the block, because there's a 4" whole in the block. It literally blew up.

I'm looking at engines right now to swap, and found a good one for a cheap price very close to me. My concern is that because it's from a 93, and mine is a 97, it won't be a cut and dry swap. I've checked the forums, and it seems that while it will fit, it might now line up just right without modifications. Any advice on that?

Thanks

 

[greg92jeepxj]

So sorry to hear your trusty 4.0 liter threw a rod . Yeah, an engine usually goes out in style when they do , the rod makes a grand exit. A friends 2.4 liter OHC just did before memorial day. Bummer. Wishing you best of luck on your next engine . Not real sure of the difference in years , have to research that myself if I needed to swap a '98 4.0 from a GC I have . Have to be sure since money is involved. It's my brothers engine. Will have to do the same . Research.