Hi everyone, i’m a new poster but frequent viewer.. have used this forum to fix a bunch of small things on my 1996 xj but after today i am at a loss. the symptoms align with many different fixes and i’m not sure which one is most logical. i’m sorry if i sound uneducated, i’m new and learning more about my xj everyday

so first a little background, i have a 1996 cherokee classic 4.0l i6 and just hit 187k miles. i took her off road a few days ago and as i was heading out of the park it just stalled. didn’t want to start back up, gave it a minute or two and then started up like a charm and drove all the way home no issues. as i pulled into my neighborhood and stopped at a stop sign it stalled again and didn’t want to start, same situation as before.

thought all was well, drove it to the market and no problems no symptoms. but on my way to work today (about 6 miles) when i was pulling into my jobs lot it stalled after a stop sign. didn’t want to start, and after a minute got a rough start but just enough to get me to my parking lot. i was about to pull into a spot and she stalled again, i ended up having to push it back to a spot and worry about it after my shift.

when i went back out it started up with no hesitation and within 30 seconds it died. in 30 minutes or so (while waiting for a tow truck) i started it again and it sat fine but the second i tried to rev the engine a bit to see if i could make the drive home it instantly died on me. ended up having to get it towed home and at this point have heard 20 different problems i could have.

i was initially thinking the CPS after some research, or that i had gotten some water in my distributor cap from some river crossings, but i’ve also been told it could be fuel pump problems, coils, etc. i know many have much more knowledge and experience than i do so i’m calling for some help!! any input is appreciated i just want her to drive again (my daily!!)

EDIT: no CEL, just removed and cleaned NSS a week ago when it wouldn’t start in park, replaced TPS and ignition coil a little less than a month ago

 

try and separate it into a fuel or spark issue

a "spark plug tester" is a super cheap, but handy tool, and the fuel pressure can be tested with a gauge

 

The major problem with diagnosing a crank sensor is that without it's signal, both the ignition and injectors shut off, as well as the fuel pump. This is why when it fails, the engine shuts off abruptly, just like you turned off the key. No stumbling like it's running out of fuel or bucking like it's misfiring.

For your edification, this is how the system functions; when you turn on the key to ignition, the PCM wakes up and primes the fuel rail with pressure, then shuts off. It waits to receive a signal from the crank sensor that the engine is being cranked. If it receives this signal, it energizes the ASD relay, controlling ignition and injector circuits, and the fuel pump relay to start delivering fuel pressure. When the engine starts running, The PCM begins controlling fuel mixture and ignition timing. When anything happens to cause the loss of the crank signal, the PCM shuts everything down. This can also happen if the security system is set. It will start, then shut off after just a couple of seconds.

Your rig demonstrates the common symptoms of a failing crank sensor, probably caused by heat. It get steadily worse over time until it totally dies. It usually doesn't set a trouble code until it has totally failed. You can check the sensor by back-probing it's connector by inserting a pin into the back side of it where the wires come out and attaching an analog meter to each wire to see if you're getting a signal while the engine is running or cranking. The wire color codes on my 2000 XJ are this;

3) 5v supply, orange wire
1) signal, grey wire with black tracer. When the crank is turning, it will be a pulsing output shown better with a meter with a needle, not digital. OR small 5v LED.
2) ground, brown wire with yellow tracer.

Check it out and get back to us please. My advise is replace it with only a Mopar sensor. A little pricey, but it will last longer than any other aftermarket one.

 

will do thank you! i ordered a mopar so i will have it if tests say it is the CPS, and will check out the CPS today to see if that’s the problem. i’ll post updates when i know more

 

Okay, just a word about terminology. We have called the crank sensor the CPS for years, ever since I joined in 2010. Lately it's being referred to as the CkPS to differentiate it from the cam sensor, which now is the CPS. I'm having a little trouble remembering this, so I generally call them the crank or cam sensor outright.

Another point. The cam sensor controls the injector timing and has nothing to do with ignition, even though it's in the distributor on older models. This is hard for people to understand. It doesn't replace the point system that most people assume it does. Ignition timing is determined by the crank sensor and other data by the PCM such as rpm, vacuum, throttle opening, 02 sensors, and engine temperature to name a few.

 

I would vote heavily on the cam sensor, which I think is called the distributor switchplate on your year and make. I had very, very similar symptoms when mine went out on the zj. Stalling at stops, hard starting, and no code. Finally it did throw the ckps or cps code. Mopar only on this, I initially replaced it with one from AZ which worked for about a week.
On the flip side, in my experience when the crank sensor fails, it just won't start.

 

The one thing that made electronic fuel injection work efficiently was the introduction of the crank position sensor. All vehicles with this system use one. It is the beating heart that makes everything work. Remember that.

 

thanks for the input!! i’ve ordered a mopar crank sensor that i’ll be putting in today and hopefully solve my problem, if not i’ll have more research to do lol

 

i’ll be putting in my new crank position sensor today. if it still doesn’t want to start up correctly would i need to look at the cam sensor next or could it be a fuel pump issue? i’ve read a lot of people having similar problems and it being a fuel system problem but i’m not the most experienced so i have no idea

 

Im lucky if I can remember to eat my donuts in the morning now I have to remember this.

 

Sucks to be you. LOL.

 

On a good day like today I do 4 of the wegmans donuts and then go auger drill some joists and run a lot of wire all day to burn it off.

 

so i’ve replaced the crank sensor and now it has no problem turning on, no more crank no start. i let it sit in the driveway to see if it would turn off again and once it got to operating temp it just died (as if i turned the car off) no sputtering or anything. any suggestions on what could be causing this? thanks in advance!

 

spoke too soon, went back out to make sure it would still fire up every time and it’s just cranking and cranking again. i’m so stuck 😕

 

No codes? Maybe try reading posts #2. 3, 5 & 6.