RANDOM STALLS: My son’s 2000 XJ — 4.0, auto, 140k, has started stalling at random. Last time was at a stop, and caused him to be rear-ended. Idles fine, temp is fine, doesn’t sound rough, tons of power, starts easy, no tailpipe smoke, no CEL. Jeep cuts out, won’t start for a minute, then starts and runs fine.

There MAY be an oil pressure issue. Gauge reads low once it reaches operating temp, and on a warm day it can read 0 and throw the CHECK GAUGE light. I’ve changed the sender twice, no change. But I read many places that a false low is common on these. We’ve been driving it that way for a year with none of the effects you’d expect of the pressure was low.

And even IF the pressure was low, would that cause it to stall and then come back find a minute later? Electrical seems more likely to me.

The distributorless ignition thingy was acting up and replaced maybe six months ago.

Any ideas? Was thinking about dropping the pan and cleaning the screen.

Thanks

 

How did you install the sender? They should only be hand tight plus another half turn or so.

The random stalls I had for my 94 Cherokee were the ignition coil, worn spark plugs, bad cap and rotor terminals inside, and crank position sensor.

 

Fuel pump test perhaps? Connector refresh would not be a bad idea.

 

1. For oil pressure issue, time to verify. Get a mechanical oil pressure gauge, remove the oil pressure sending unit and screw in the mechanical gauge. Then you'll know. The oil pressure spec for the 4.0 engine is 37-75 psi over 1600 rpms with a minimum pressure of 13 psi at idle. If your oil pressure truly was near zero, you would normally hear some concerning noise coming from the engine.

2. For the stalling engine, if the engine starts cleanly a minute after stalling, it could be a crankshaft position sensor starting to fail. What you describe is not uncommon when this sensor starts to fail. The crank sensor can fail without setting a check engine light or storing a code. If you can find a genuine MOPAR sensor, although I've heard they can be difficult to find. Aftermarket crank sensor are very "hit and miss" with a lot of miss. When I was wrenching on Jeeps, I wouldn't install anything but a MOPAR crank sensor.

3. As for dropping the pan and cleaning the screen, likely not necessary. Drain and fill with DexIII/Merc transmission fluid. Do it 2 or 3 times with short driving intervals inbetween if it hasn't been done before.

Good luck and keep us posted!

 

I can't see how the issue you are having could in any way be oil pressure related. If it was, it certainly wouldn't be starting up a minute later.

Drop what pan and clean the screen? The trans? While a drain and fill would be a good idea, I can't see the trans causing the issue either.

Over the summer, I had a similar issue where my Jeep would randomly stall and be tough to restart. It kept happening and I would not get a CEL. Eventually however it did, and it was for the TPS. Replaced and all is good.

Sounds like you have a sensor about to fail. You can wait until it throws a CEL. Arbitrarily replacing sensors would get costly quick, so I would not recommend that path.