Help please! 99 XJ cutting out/Dying

Hello everyone new to the group and having an issue with my 1999 Cherokee sport, 4.0L, auto. I'll try to do the short version. Had issue about a year ago and turned out it was the crankshaft position sensor, I replaced it with a oem sensor and no change... took it to a shop and they told me I had installed a position sensor for a 2.5L. Me not knowing any better said "ok put the correct one in"... so they did and problem solved... now I'm having the exact same issue and Ive replaced it yet again. only thing is it didn't not fix my problem... so what else I have done.

I've replaced the fuel pump (Bosch) csp sensor oem replacment, O2 sensor (Bosch) the ecm/pcm is only about a year old it and iac, map sensor and tps were replaced the last time I had this issue along with a completely new distributor/cap, rotor, wires and plugs The rig only has 120k miles on it. I've done a harnes shake test, checked all electrical connectors pulled and cleaned all grounds under the hood, checked relays as best as I know how, checked ignition under the column... I'm completely at a lose here and ripping my hair out! Please any info would be greatly appreciated

 

I'm not the best mechanic on this site but this might start a good conversation..lol....have you checked the timing or belt...there are a lot of great guys and gals on this site ..hopefully one will chime in

 

Hey Brian. Welcome to the forum.

I am not one of the members Drd88 mentioned. I am by no stretch of the imagination a mechanic. As I was reading your post. I had a similar issue with my 00 XJ. And it turned out to be the distributor. But as you replaced that. I'm at a loss honestly. Theres a couple really good XJ guys here that hopefully can help. Hang tight.

 

Hello there flexj99 what was the original problem with the jeep a year ago you said crank position sensor but was it a hard start loss of spark. Just trying to get all the info. Thanks

 

Thank you for the welcoming

No it would start up fine and run, the symptoms are almost identical to what I'm having now, violent missing, gauges dropping out and occasionally dying. Sometimes as I would sit at a light in gear the rpms would come up as if I was power breaking it to launch but that's the only symptom I'm not experiencing this time around. It will fire right back up and run again for moment then right back to the symptoms. The last time this happened it had been doing it for a while then one day I got off the freeway, stopped at a light the jeep reved up high had really hold the break to keep it from jumping on the car in front of me the it dropped out raced back up and finally died and would not start up again. It all happened so fast I hardly had time to react. That was when I took it to a shop. The shop charged me almost $500.00 to do what I'd already done... I'm really trying to avoid this again. Thank you very much for any info you might have to help.

 

I'll be honest I'm having a hard time following your symptoms here... if you are having a change in idle that makes the idle raise in rpms only a few things can cause this. Idle air control, vacuum leak or cruise control unit pulling the throttle open when it shouldn't. Somehow air is getting into the engine. I do know that these jeeps share the same 5v power from the ecm to just about ever sensor they have meaning that if you have an injector short out it can steal the voltage from other sensors and vice versa. If you could break down your symptoms for me maybe I can give you a better path.

 

So these are the current issues?

Any new developments on this issue Brian?

I would check the ground strap that goes from the rear of the engine to the firewall. It could have become loose.

 

Yes after days of ripping my hair out a friend of mine came over he isolated and tested the ignition coil and we came to figure the coil is bad. I have a MSD ignition box and from what he was explaining to me the MSD was taking what little spark the bad coil was sending amplifying it and send it through in turn making it seem as if the coil was good. I replaced the coil and she runs like a champ! Thank you all for your advice and information. It's greatly appreciated

 

Awesome dude. Good you found the issue. And a great post for any one running an MSD ignition, and has issues in the future.