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XJ shuts off at cruzzing speeds? help!

alcobejo

NAXJA Forum User
Location
Chino Hills, CA
:repair::exclamatiplease help my xj will shut off at cruzzing speeds usually when it is at a low rpm or sometimes at a high rpm. but the engine would shut off and rairly it would start up again.. when i start the xj it cranks i have changed my fuel pump and filter and i tested my altanator and battery everything looks rite. if you have any clue of what this problem is please reply!! i am a newb but im gessing it is a sensor that is on the throttle boddy due to my intake and tbs it sounds like it is bogging out ... if u have any ideas please tell cuz this seems very dangerious on the streets.
 
im sorry i no the basics of a car i meen im not a mechanic but i no a good amount.. what exactly is my tps? and what does the crank position sensor or tps have anything to do with it and would i have to replace them? if thay are the cause of
 
The TPS is the Throttle Position Sensor it tells the computer how wide open the throttle is so it can know how much fuel to put in the engine. The Crank Position Sensor tells the computer exactly where the crank shaft is in its rotation helps the computer make its calculations on timing and other various figures. The computer for the engine is quite an amazing thing if you really sit down and examine what all it looks after. First thing that would help a lot of us out in answering your questions and helping you solve your problem is what year is your jeep, what motor does it have, automatic or manual transmission, and is it 4x4 or 2wd? Pretty much the basic information that you should give each time you post a problem like this. Not hating at all man since your a newb we all get the lecture some are mean about it and some are understanding like me. But one thing I had happen on my 97 is my temp. sensor went bad and it was giving me all kinds of hell like dieing in the middle of traffic, not always starting without having to give it some gas, high idle after initial start-up, just a whole bunch of crazy things that got cleared up once I replaced it. Not saying this is your problem but if your temp gauge isn't showing a reading its worth checking and replacing if necessary. But give us some of your vehicle info and we will be able to help you out better. The TPS is also a big problem causer as well as the CPS so either one of those could be it and I have had to replace both on my 97.
 
Alright now that can better help us solve your problem. Now if I am not mistaken on that year there should be two electrical connections on the back side of the throttle body one looks cylinder like and that is the Idle Air Control valve or sensor some refer to it differently but its known as the IAC which could also possibley be your problem but the other connection there is the TPS both are relatively inexpensive to replace but sometimes you get a wild car and a particular year may have an unusually expensive one but the only way to find out is go to local parts store like autozone etc. and price it up. I am not totally sure of the exact location of the CPS I know its on the back side of the block but I am not sure exactly where so maybe someone else can better help point that one out for ya. I would start with the TPS and then move to your IAC then try the CPS. Does it hesitate or stumble or surge high in RPM at all? We need all your symptoms.
 
the CPS is on the top side of the trans behind the block. change it last because its a pain in the a**

Crankshaft_Position_Sensor_diagram.jpg
 
I would replace the CPS. I picked up a Jeep last month, and when on the highway it started bucking and shutting off. Then I woudn't be able to start it again. Then I would, and it would just shut itself down every once and a while. Then it wouldn't start for long periods of time. Changed the CPS and haven't had a problem since. Same thing happened to my dad's TJ.
 
I didn't even know you could get those kind of symptoms with a bad CPS mine went bad and just flat out wouldn't start again had to have it towed to a shop since it was a long time ago when I didn't know all that much yet. Looks like it could be any one of these sensors but from what Bgester described it seems what he had is pretty similar to your situation so I say try replacing the CPS first and see what that does for ya.
 
the CPS is on the top side of the trans behind the block. change it last because its a pain in the a**

It can be a pain in the butt, but if you use a u-joint socket extension, then it does help.


I definitely think it is the CPS. As you said, it does it alot at low RPM. I would have to switch to nuetral and rev it up when I came up to a light so that it wouldn't shut off. If I could keep the RPMs up, it was usually alright, but it would die at high RPMs as well.

Also, if you have a multi-meter, you can unplug the CPS, and measure the resistance. If it reads a low to zero resistance, then it is shorted out. I compared it with my other Jeep that was running, and I came up with about 650ish Ohms for the good one, and around 220ish for the shorted CPS.
 
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