My aunts jeep demon
 

My aunt has a 98 cherokee with 4.0 I6. She claims it dies out on the highway and sometimes at idle but only when the engine is hot. I had the car for a whole day and was only able to get it to stall twice in the garage and thats it so i see no pattern. Ialso tested the fuel pressure on a long test drive and saw no issues.

I suspected the hall effect switch so i switched that out as well as replaced the over do plugs,wires,cap and rotor and the problem went away.

Oh and it threw two codes...
1. Primary ignition circuit
2. Crank sensor signal

I cleared the codes and did the tune up and neither codes came back after running the jeep for quite awhile.
I just gotta call today that its stalling again!
Any Ideas?!?!

Im in a real pinch hear thanks

crank position sensor is my guess. my buddies sentra does the same

wouldnt the code keep popping up?

i don't know what the conditions are to set the code. maybe a wire is pinched, broken, or rubbing. could be the sensor itself. could lie within the computer. had a dodge neon that showed all the signs of a bad crank sensor but the computer took a smack when it got into an accident and broke the wire within the computer.

thats what im thinkin but i wanna avoid the PCM if possible...

The 4.0 Jeeps are NOTORIOUS for having bad Crank Position Sensors. That's the one located on the back of the block, above the bellhousing. My mom had the same problem with her '99 4.0 Grand Cherokee, and a bunch of guys over on Jeepforum have experienced the same thing. Good luck with it!

Very often when crank sensors go bad they just skip count. The code will only show when it is actually f'ing up, not all the time while it is cruising along.

I would start there and see if it clears up the ignition circuit, the crank sensor can cause that, not the other way around.

if the crank sensor is messing up it will actually knock out the PCM, thus clearing any OBDII data like codes. get a crank sensor for it and it should be good to go.

oh yeah now i remember doing one of these. it was reading like 800mph or something retarded. yeah these guys are right.

alright cool thanks guys i'll let you know how it goes.

FYI, the crank sensor went on my '96 Cherokee a few weeks ago and never set a code.

- Justin

put the crank sensor in today....book labor time was 0.7 and it took me closer to an hour and a half due to my fat hands not being able to reach that far under the transmission

oh and when i first brought it in the garage i scanned it and it had another history code for primary ignition circuit

thanks for the info guys and fingers crossed..i'll post something if she calls me back lol

did it have the same stall issues that my story had or was it dead?

Nah, mine just died on the road and wouldn't restart. More of a glorious failure than an intermittent one. ECM never picked up any problems though....

- Justin

well the effing thing is stalling again! MERRY CHRISTMAS!

ive exhausted every idea so i dunno:-?

Search / post up here: http://www.jeepforum.com/forum/forumdisplay.php?f=11

- Justin

tried it....no dice

i'd start tracing wires. my buddy had something similar in his grand cherokee and i believe a wire rubbed through the insulation and would ground out on the body on ocassion.