hajenkadenkados

Recently the engine on my 2000 sport 4.0 has been shutting off while driving down the road. All of the electronics stay on and the first few times it started right back up. The last few times it happened it wouldn't start right away but after about 5-10 min it would start right up again. I've only been driving it back and forth to school and it seems to happen about 4 miles out from wherever I start from, once the engine is warm. There's no check engine light that comes on. Its not happening when I pull up to stop signs or light so I don't think it is the IAC. I'm not too experienced with working on my own stuff since I've been learning on my Jeep, which is my first vehicle. I have done a few thing on it so I'm not mechanically incompetent but I don't know where to start with this one. Any help is greatly appreciated.

MI_Offroad

I had the same problem after I changed my oil, filter, sparkplugs and cleaned everything down there. The engine would turn off and everything else would stay on while driving.

Found out the oil pressure sending unit casing cracked and opened up causing the three little wires inside to touch each other and kill the engine. With the engine running, reach down and wiggle the sending unit casing and see if the motor dies.

I was completely suprised that a little sending unit could be a kill switch.

RTorrez1

It sounds like your CPS is going out. When they start to go out at times when they heat up and shut the Jeep down. Are you getting a cel?

tjwalker

The most common cause of the engine intermittently shutting off on the Jeep 4.0 engine is a failing "crankshaft position sensor".

They can be tested, but testing of something that is intermittent often is of little value. Often they will fail without setting a check engine light or a code.

If you buy one, do yourself a favor and buy a Mopar unit directly from the Jeep dealer for best reliability and longevity. No lack of threads of issues with aftermarket crank sensors.

F1Addict

I will triple the vote for CPS (Crank Position Sensor) and will reiterate tj's recommendation that you avoid the Chinese made Duralast CPS available at Awful Zone. I know there's a fairly reliable testing procedure for RENIX era CPSs but I'm not sure about later models.

For the record, my agreement with tj regarding imported CPSs is based solely on what I've read, not personal experience. I installed a Duralast in mine a few months ago and have had ZERO problems with it, so far. I think it was $28, which is between 1/2 and 1/4 of what I've seen paid for an OEM unit. I've heard of the Duralasts failing out of the box, though so I probably just got lucky and since they're kind of a pain to replace, it's best to only have to do it once.

hajenkadenkados

Thanks for all the help. My dad has a buddy who works at the Jeep dealership in town so I'm having him take a look at it and hopefully if that's the case then he will be able to get me one for a bit cheaper than usual.

tjwalker

If you can wait for a few days for shipping, I generally buy my genuine Mopar parts from moparpartsonline. In fact, I just purchased a crank sensor for my 99 XJ for about $50; quite a bit cheaper than most dealerships.

https://www.moparonlineparts.com/

stev-o

I have haf a duralast cps for a few months now and it has worked great No complaints

jomps

I read it could be battery: load test it, or loose wires at ecu

hajenkadenkados

it was the CPS. had my dad's friend help me out with it and now she's running like a champ again. thanks for the help

RTorrez1

It's cool that it up and running again.

stev-o

It's always the cps