Philippe L.

Hello everyone

I'm one of very few proud EU Cherokee XJ owners (4.0 92' - 271.000 km's). Drove it to Spain and back, both trips (1600km / 1000 miles each) in one separate day. Had some issues, but got home great.
So last weekend my girlfriend and I did a longer trip (150 km / 100 miles). After some time the oil indicator went all over the place, going from 40 psi to well over 80 psi.
I also had this issue coming back from Spain, which I found to be a hole in of the vacuum lines going to intake filter housing. When I found this, I had a very rough idle and the engine even stalled.

The current situation: good idle when hot, but sometimes suddenly almost dies. Engine does correct itself, so it doesn't actually stall this time. Oil pressure indicator all over the place when on a "long" trip (1 hour+).
At idle (sometimes when hot) I hear a rattle coming from under the car near transmission.
Any suggestions?

Spawn XJ

If the rattle goes away with throttle or when you put it in gear, personal experience says that you may have a cracked flex plate.
As far as the erratic oil pressure readings go, have you checked the sending unit itself? I didn't realize I had broken mine while replacing the oil filter, and then my gauge went wacky and I found the problem. This was on my 99 though....
I'm headed out to the garage and I will see what I can see on my 92 if I can visualize what could be a problem.

lawsoncl

A bad oil pressure sensor is much more likely than an actual oil pressure problem. A hole in a vacuum line, especially the one going to the MAP sensor needs to be fixed. For the rattle, also look at where the exhaust passes over the transmission support crossmember. If it's hitting there, you may need to look at the motor and transmission mounts.

Idunno

With my 96, if this is even relevant to your 92 configuration, my crankshaft position sensor went through a slow death cycle of causing the engine to shut down briefly while at speed, like a stumble, and then catch again. It did this over a period of months, actually, until one day it died and I was lucky enough to coast into an empty parking lot. Between stumbles and its final complete failure, it would kill the engine completely. While rolling I'd have to slip into neutral and restart with the key. That worked for a few episodes. Sometimes I'd have long crank times but it would catch. I replaced it with a $45.00 cheapo sensor (Rock Auto) and got exactly three miles down the road towards home when it failed. I bought the MOPAR sensor and haven't had trouble since.

cruiser54

While you're at it, clean the throttle body.
what do the plugs, wires, cap and rotor look like?

Philippe L.

It's the first car I've ever worked on myself. Great car to learn from!

I will check spark plugs & other suggestions tomorrow.
Where is the oil pressure sensor located?
Should I consider replacing the CPS?
I'll definitly look into the vaccum leaks another time but didn't find anything yesterday.

I did change the engine oil and filter(5W40) and ATF (Dex 3) last weekend. Could this have anything to do with these problems? The levels are fine.

Thanks guys

Philippe L.

I forgot to add I'm running on LPG since I own it (10.000 km's) which it actually does very good.
So I'm pretty sure it's not something fuel related.

Idunno

Agreed.
I would definitely change the CPS if the symptoms are similar to the ones I mentioned above. Sitting in the vehicle facing forward, it's located at the 11:00 position on the transmission bell housing just behind the engine and immediately beneath the firewall. It's mounted with 2 11mm bolts and has a rubber gasket surrounding it. The harness runs forward and is on a cable clamp on one of the head bolts, IIRC. Kind of a bugger to get to with big hands from the top side. It was easier changing it by coming from beneath with some long ratchet extensions and an 11mm socket on a u-joint. The oil sensor will be near the oil filter, or at least it is on my 96.

Philippe L.

Didn't have the time to have a look at it yet, drashing rain!!!
What I did have time for was picking up the right socket for the spark plugs and a gap measuring tool.

I'm wondering if a broken/cracked flexplate would be "hearable" at higher rpm's?
Also, I have the feeling that it's heat related. Can anyone point out where to look at this diagram (if one of them is ...)?

Philippe L.

So I found some time to change the spark plugs today:
The service manual said 0.035", which I read as 0.35mm. So after changing them, the engine ran even worse lol.
Got them out, changed to the correct gap and put them back. Runs fine now. I'll follow it up during the following days.

I had some time left which I spend by looking for the rattle noise. It's definitly comming from the catalytic converter.
There is no play in the mounting bracket. The sound seems to come from within or the heat shield (which also have no play).
Any tips?

Idunno

The cat has self-destructed internally and what you hear are the innards rattling around. Time to change it.

Philippe L.

So when revving the pieces get trapped, which is why you don't hear them anymore?

There are bolts on both sides mounting it in the exhaust system. Should I just remove it and have a look first?

Idunno

With power on, the loose pieces are basically held in place by the flowing gasses I guess. My 96 & 98 both had the same cat rattle. It was worse in the 96 (older) with acceleration than it was in the 98. I replaced them with the mufflers as a unit. No more rattle from either. There was a power range where they were mostly silent but ranging up and back through those bands (RPMs) got them rattling.

doublechaz

As a test, you could pull the cat out and dump the chunks out and put it back. But long term you should replace it since the chunks you dump out are the part that makes it do it's job.

Canadiantech

I had similar issue with mine, but mine got worse over a year, i did a bunch of part swapping, nothing seemed to help. I tore into the wiring and found the main wire from the ASD relay just hanging in by a thread, repaired the harness and have had zero issues since.