Doesn't make sense...?

[Punisher]

I went to a buddy's house to pick him up and head out to Miami to serve court papers in the area and we decided to take the XJ instead of his V8 gas sucking car...
Drove out and stopped at the rest area about 60 miles from where we needed to go and we already drove 110 miles with the A/C on and all and everything seem to run great (no problems) then we left the rest area and got into town and go into some traffic and notice the jeep started to hesitate and I hit the gas and it stalled... and I was like now WTF?!...
I attemp to start it and it sounded like its starving for fuel and I try it 4 more time and finally started and drove right in to the gas station and popped the hood and look to see what it was... I reved the motor and it runs fine no problems and I put my finger on the releash cap of the fuel rail and gas shot out so I had good pressure... well we tried it again and left the gas station and headed to where we needed to go and it did it again stalled.... Now I'm getting a little pissed....
sat in the middle of the road again and finnally started so I got to where needed to go which was only 2 miles up the road and while my friend went in side to serve his first paper I looked under the hood and see nutin wrong good gas pressure and so for so I started up and let it idle and just watch to see what it would do then all of the sudden it started to lope and dies... I let it sit for a minute to cool off then my buddy came back out and we sat for a bit and started it up and went to the next place.... got on the high way and it drove just fine (high rpm) but then we got stuck in bumper to bumper traffic and (what happens?) it dies again!!! and I noticed it only dies at low idle but on the highway or doing at least 35MPH it runs fine... no overheating or nothing... but as soon as I had to stop or run as an idle it studders and dies and its take a bit to start up... so we pulled off the highway as the traffic was so bad and got to a safe place and looked on my phone for anybodies number on xjtalk to see WTF could be going wrong so I can get back home!! and the only number I had on me was weldmen (curt) but he thought it could be the TPS and I was thinking the same thing but didn't have any tools on me as my buddy called me so early to rush me out and I forgot to grab it just incase... well we went to a place to park the jeep and did our serveing on foot which was nice cause it was all within 5 blocks from each other and stopped at subway to grab a bite to eat to let the jeep kool down, so we got done and drove home without any trouble at all.... But I want to know what the HELL was causing all this trouble in the first place and get it fixed so I dont have this shit happen to me again....
So guys what should I look or fix first?... I was thinking 4 things TPS, coil, plugs and wires.... at they are the only thing I havn't replace on this
to remind you I'm working on a 1996 XJ w/ a 4.0
Thanks for any input :thumbsup:

[msmoorenburg]

Sounds like a crank trigger going bad (that's the issues with mine) see if its only during certain rpm's

[Mudderoy]

Sounds like a crank trigger going bad (that's the issues with mine) see if its only during certain rpm's

What is that? The CPS the ECU?

[Punisher]

What is that? The CPS the ECU?

Its the CPS...

[Punisher]

Sounds like a crank trigger going bad (that's the issues with mine) see if its only during certain rpm's

but if thats the case wouldn't it be noticable on all rpms?
It's only doing this on Idle but when I get on a higher rpm it drive great no misses...
And also when I had the guy at the auto part use the OBD II wouldn't it come up telling me its going bad?

[msmoorenburg]

but if thats the case wouldn't it be noticable on all rpms?
It's only doing this on Idle but when I get on a higher rpm it drive great no misses...
And also when I had the guy at the auto part use the OBD II wouldn't it come up telling me its going bad?



It may say miss fire. below is Autozone description of the symptoms of a bad trigger



Features & Benefits
Duralast products are engineered and manufactured by Wells Manufacturing, a leading global supplier of advanced vehicle electronics solutions for original equipment and replacement applications. Every component either matches or improves on the OE design to ensure fast, easy installation, superior performance and reliability. Wells offers extensive application information and technical support via its Tech Line at 1-800-558-9770, as well as in-depth product and repair videos at www.wellsVE.com and through the “Wellstech” channel at www.YouTube.com .

* The crankshaft position sensor identifies position of the crankshaft to the ignition control module (ICM), engine control module (ECM) or powertrain control module (PCM).
* When not replaced, vehicle could experience no- or hard start, long crank time, misfire, lack of power, excessive hydrocarbons in oil, spark plug fouling, catalytic converter failure, poor fuel economy, CEL/MIL illumination or intermittent shutdown.
* Designed to meet or exceed OE specifications in form, fit and function.
* Global coverage for import and/or domestic applications.

[Mudderoy]

My el-cheapo CPS I got from ebay ($40) I had to replace because it wasn't working correctly with the Firewire ignition system. I replaced the NEW CPS with my factory original.

I just called the local Chrysler Jeep dealership. They have 5 in stock and they are $114 each.

[LizardRunner]

My CPS was bad when I bought da lizard, it only goofed up at 1000 rpm, any other rpm level and all was good. I had the auto parts store test for any codes and nothing showed up as bad. The parts store guy told me that just because the CPS and TPS showed they were good, didn't really mean they were. I asked a couple of jeep guys I know about it and they both said "Replace the CPS".

I replaced the sucker and have not had any issues ever since. While I was dealing with the faulty CPS I noticed that the rpm's would drop to zero when the engine would die for no apparent reason.