'98 ZJ Stalling While driving, now only starts after sitting long periods. - JeepForum.com
Search  
Sign Up   Today's Posts
User: Pass: Remember?
Advertise Here
Jeep Home Jeep Forum Jeep Classifieds Jeep Registry JeepSpace Jeep Reviews Jeep Gallery Jeep Clubs Jeep Groups Jeep Videos Jeep Events Jeep Articles
Go Back JeepForum.com > Models > Jeep Grand Cherokee & Commander Forums > ZJ Grand Cherokee Forum > '98 ZJ Stalling While driving, now only starts after sitting long periods.

Rough Country Deals at JeepHut.comSave at JeepHut on Smittybilt Soft topsUp to $75 Cash Back on Your ARB Fridge Freezer Purchase

Reply
Unread 04-21-2013, 08:08 PM   #1
EveryDayZeeJay
Registered User
1998 ZJ 
 
Join Date: Apr 2013
Location: American Fork, Utah
Posts: 17
'98 ZJ Stalling While driving, now only starts after sitting long periods.

Hey guys, new sign up but long time lurker.

My '98 ZJ with the 242 4.0 inline 6 has started stalling on me randomly while driving, it has done it at different speeds. (back roads, main roads, freeway.) I am a IT guy by trade but worked in a race shop in my teens (Lozano Bros Porting) Used to be in San Antonio Texas. But I've torn down and washed a few hundred v8's and I'm somewhat mechanically inclined, but super newb at automotive electrical.

The first time it happened was about 3 weeks ago, I was on the freeway using cruise control and the engine just shuts off, I still have power etc and coast to the break down lane. I cranked on it a few times and eventually got it to fire within a couple of minutes and went on my way. About 5 miles later and off the freeway it felt like it was going to cut out then came back, split second it seemed like. Drove it home no issues.

Next day I go to work and come home for lunch with no issues. I leave to go back to work (within a half hour) and the Jeep again stalls a few blocks from home. I crank and crank on it till the point the battery dies. (old battery 6 years out of warranty on a (N)EverStart.)

I have a mechanically inclined friend come help me move it, we don't hear the fuel pump, so we put a few spoonfuls of gas down the tb. With the aid of cables we jump it and it's starts and sound super rough. We get it back to his lumber yard and I shut it off, no start again. I let it sit for a few days and My buddy thinks it is the fuel pump, so I go to pepboy and get a Carter Fuel Pump Assy and we drop everything and replace it. Jeep runs strong and I drive it around town for a few and put a quart of oil in (constant leak, bay is messy is as hell)

Next morning I go to work and sitting in the lot sipping some coffee with it running and it dies on me, won't fire but cranks and cranks till battery is dead again. (still old battery.) At lunch I get a jump and it fires right up, (no gas needed in TB this time) I took it to Wally World and got a brand new battery.

Drove awesome for the next 4-5 days. Then it stalled out again..., far from my house, thankfully a friend came to assist. We tried jumping and no go, would crank really really strong being hooked up to his truck. I ended up leaving it to sit for about 2-3 hours and came back prepared to tow it, I got the crazy idea to try and jump again and it fired right up. I baby it to his house and leave it running to see if it will stall while idling for about 30 mins, I had him follow me home and no stall issues. Was good for about 2-3 days more with only short distances traveled before I parked it (work and home is less than 2 miles for both wife and I) It stalled again on my way back from lunch this past thursday. I let it sit for 2-3 hours walk back to it and it starts up second time.

I get it home and let it idle and it stalls again. The stalling is getting more and more frequent and once it stalls it will not start again until it sits for a several hours or more. It fires up every morning here it Utah and it's still mildly chilly in the mornings. So I drive it 2 more days just the quick trips to work and it stalls on my wife last night a block from the house, I let it sit for about 4 hours and it starts up after a few cranks, the gauges went all nucking futs on me and then went to normal. I put it in it's parking stall and it stalls right out, I can start it but it dies again immediately. I let it cool off until this morning and start it up first try, first crank, let it come to temperature and it stalls on me again. I have tried the on/off/on/off/on with the ignition but can not get it to pull any codes. I do see the CEL the first seconds when the key is turned to on, I think I may be able to rule out the PCM?

So with a entire fuel pump assy and a brand new battery installed, from my reading, it could be the crankshaft position sensor, an o2 sensor's harness near the drive line, the PCM and/or it's connections/harness.

What else could I be looking at, I'm a limited income and taking it to a mechanic is likely out of the question unless money falls from the sky.

My engine bay and engine is filthy as hell because of some oil leaks that I have probably ignored for for too long instead of just keeping it topped off.

I am hoping one of you wizards has a sure fire way to troubleshoot this or point to the most likely cause with the details I have provided.

I apologize for the very long read but wanted to give as much info as possible on my issue occurrences once it started.

Thanks in Advance Guys!


Last edited by EveryDayZeeJay; 04-21-2013 at 09:27 PM..
EveryDayZeeJay is offline   Reply With Quote
Unread 04-21-2013, 10:17 PM   #2
surprise_rice
Registered User
1996 ZJ 
 
Join Date: Feb 2013
Location: long beach, ms
Posts: 7
http://www.jeepforum.com/forum/f13/1...talls-1407423/

"The Dirty Dozen"

Goin through the same mess down here in the south. Got mine running well enuff to limp me back and forth to work until I get another paycheck to JEEP. Lol. She's runnin like a dog, but thats better than the last 4 days. Replaced the fuel pump due to prior issues with piss poor fuel pressure and replaced the whole distributor because there was (IMO) excessive play in the drive. My no-start was all along CPS though with a busted wire from my tranny shift cable rubbing on it (where there should be a shield I learned from the junk yard today).

Still having terrible idle, gonna have to get new plugs on the way home from work tomorrow. I'm pretty sure my low side o2 sensor playing havoc as well. Not to mention the fact that now I have a swollen muffler and cat from all of the fuel. I may get one of the welders I work with to rig me up a stepped down 2 foot section of tail pipe with a turn down on it... just to eliminate the choke hold my cat and muffler are so kindly providing right now
surprise_rice is offline   Reply With Quote
Unread 04-21-2013, 11:08 PM   #3
angry_trucker
Registered User
1998 FSJ Cherokee 
 
Join Date: Feb 2013
Location: kitchener, ontario
Posts: 115
Just a guess here, but based on the info I came across on these forums and others it looks like your PCM or the connecting harness is acting up....
One simple way of finding out, is to move the harness around and tap the PCM in different spots, while the engine is running...if the engine changes the way it is running, you have found your problem...

The PCM's and the PCM connections in Grand Cherokees are prone to failure and should be the first to be checked....

If it turns out to be a bad PCM, from what I understand it is better to stay away from the re-manufactured units and you are better off spending the extra $ for the genuine MOPAR replacement PCM....
The PCM is mounted to firewall behind your coolant overflow tank.
__________________
98 Jeep Grand Cherokee Laredo 4.0
Selec-Trac
Everything stock.
angry_trucker is offline   Reply With Quote
Unread 04-21-2013, 11:12 PM   #4
EveryDayZeeJay
Registered User
1998 ZJ 
 
Join Date: Apr 2013
Location: American Fork, Utah
Posts: 17
Yep, look at that.

I'm leaning towards a thermal failure of the crankshaft position sensor, but I hate throwing money at items that will likely not fix the issue. I'm hoping more jeep guys can throw their experience in the mix.

I've read probably hundreds of posts now on the issue both here and some other places.

First time I've had an issue with a Vehicle and no CEL or codes to go off yet. I am under the impression that the on/off/on/off/on should get it to show atleast maybe a 12 or 55 but I get nothing on my rig.

The CEL does show up for the 3 or so seconds like it should, so it's "booting" when it's stalling/won't start which leads me to believe the PCM is okay and pointing more towards the CPS.

I already know I need to do plugs/wires cap and rotor and probably an ignition coil as these have never been done since I bought the jeep in '09.

My cat converter rattles like crazy too, but always has and never affected the way it runs or starts.

I don't have a trusted mechanic as I never really needed to have one and I don't have many friends who know much about jeeps. That leaves forums and google as my best sources unless I save up for a shop visit, highly unlikely though.
EveryDayZeeJay is offline   Reply With Quote
Unread 04-21-2013, 11:16 PM   #5
EveryDayZeeJay
Registered User
1998 ZJ 
 
Join Date: Apr 2013
Location: American Fork, Utah
Posts: 17
Quote:
Originally Posted by angry_trucker View Post
Just a guess here, but based on the info I came across on these forums and others it looks like your PCM or the connecting harness is acting up....
One simple way of finding out, is to move the harness around and tap the PCM in different spots, while the engine is running...if the engine changes the way it is running, you have found your problem...
When I have got it to run, I've tried playing with the harness and pressing the connectors into the PCM more, this had no effect.

It's only stalling when warm it seems. From a cold start it fires right up, runs a little rough, could be misfiring as well, don't know how to check or what it feels like. Once up to temp it will just kill the engine. I just checked a few minutes ago and it fired right up again.
EveryDayZeeJay is offline   Reply With Quote
Unread 04-22-2013, 04:57 AM   #6
ratmonkey
R.I.P.
 
ratmonkey's Avatar
1997 ZJ 
 
Join Date: Dec 2006
Location: , Pennsylvania
Posts: 19,805
Key trick does not work on 1998 jeep vehicles.

Sounds like you've got a handle on trouble shooting.
I'd use a heat gun, on very low, to heat up suspect components individually to test them.
__________________
'97 zj 5.2, some stuff, some other suff, and some things that even work sometimes.

ratmonkey is offline   Reply With Quote
Unread 04-22-2013, 06:32 AM   #7
EveryDayZeeJay
Registered User
1998 ZJ 
 
Join Date: Apr 2013
Location: American Fork, Utah
Posts: 17
What would you heat up? What else could be heat related that would cause the engine to straight stall, the stall doesn't sputter or buck either, it just acts as if someone turned the key to the off position while driving.

Another question, when I have gotten it to start and it's running rough, almost feels as if it is misfiring. If the engine misses on any cylinder it should throw a CEL? Or could this be the timing being funky that I'm feeling due to a faulty crankshaft position sensor?
EveryDayZeeJay is offline   Reply With Quote
Unread 04-22-2013, 09:07 AM   #8
angry_trucker
Registered User
1998 FSJ Cherokee 
 
Join Date: Feb 2013
Location: kitchener, ontario
Posts: 115
I have bookmarked the testing procedure for the crankshaft position sensor...it is my understanding that they go bad very often:
http://www.jeepforum.com/forum/f13/h...57/index3.html

Also, I don't think that the PCM can be ruled out just yet...i think I have read a while ago, that someone was experiencing the very same problem you describe.....
Some joints inside the PCM expanded from the heat and once the vehicle hit certain temperature they would lose contact....Im thinking maybe you can try to put up some sort of heat insulation in front of the PCM to see if that would have any effect?
__________________
98 Jeep Grand Cherokee Laredo 4.0
Selec-Trac
Everything stock.
angry_trucker is offline   Reply With Quote
Unread 04-22-2013, 09:18 AM   #9
EveryDayZeeJay
Registered User
1998 ZJ 
 
Join Date: Apr 2013
Location: American Fork, Utah
Posts: 17
Quote:
Originally Posted by angry_trucker View Post
I have bookmarked the testing procedure for the crankshaft position sensor...it is my understanding that they go bad very often:
http://www.jeepforum.com/forum/f13/h...57/index3.html
As for taking the connector apart is there a good write up or how to on how to make sure you disconnect them properly? I don't wanna break anything trying to get the connectors apart incorrectly.

Sorry for being so noob

Also do I want to check the CPS while it's in the middle of a stalling fit or when I can fire it up on the first try from a dead cold start?
EveryDayZeeJay is offline   Reply With Quote
Unread 04-22-2013, 06:23 PM   #10
EveryDayZeeJay
Registered User
1998 ZJ 
 
Join Date: Apr 2013
Location: American Fork, Utah
Posts: 17
Anyone take this one on?
Quote:
Originally Posted by EveryDayZeeJay View Post
Also do I want to check the CPS while it's in the middle of a stalling fit or when I can fire it up on the first try from a dead cold start?
EveryDayZeeJay is offline   Reply With Quote
Unread 04-22-2013, 06:52 PM   #11
98ZJLaredo
Registered User
1998 ZJ 
 
Join Date: Apr 2013
Location: sanford, Florida
Posts: 3
A bad or incorrectly adjusted crankshaft position sensor will cause a lot of different problems. A bad sensor will cause rough idle, misfiring, stalling, and no start. A sensor that is too close (not enough air gap) will cause rough idle, backfiring at low RPM. A sensor that is too far (too much air gap) will cause high RPM backfiring/stumbling, misfiring. The correct air gap should be 0.032".
98ZJLaredo is offline   Reply With Quote
Unread 04-22-2013, 08:11 PM   #12
EveryDayZeeJay
Registered User
1998 ZJ 
 
Join Date: Apr 2013
Location: American Fork, Utah
Posts: 17
Quote:
Originally Posted by 98ZJLaredo View Post
A bad or incorrectly adjusted crankshaft position sensor will cause a lot of different problems. A bad sensor will cause rough idle, misfiring, stalling, and no start. A sensor that is too close (not enough air gap) will cause rough idle, backfiring at low RPM. A sensor that is too far (too much air gap) will cause high RPM backfiring/stumbling, misfiring. The correct air gap should be 0.032".
How would I go about adjusting the new CPS when installed, what's the best way to ensure the gap you're stating?

I have no experience with this particular part, I know where it is, where it plugs into the harness and that it's going to be hell to get at it.

Any further guidance is appreciated, I'm feeling confident with all the advice I'm getting here and over at rme4x4
EveryDayZeeJay is offline   Reply With Quote
Unread 04-22-2013, 09:24 PM   #13
ratmonkey
R.I.P.
 
ratmonkey's Avatar
1997 ZJ 
 
Join Date: Dec 2006
Location: , Pennsylvania
Posts: 19,805
there is no adjustment for the cps, it's either right(and mopar) or wrong. bwd and other aftermarket brands are often wrong.
__________________
'97 zj 5.2, some stuff, some other suff, and some things that even work sometimes.

ratmonkey is offline   Reply With Quote
Unread 04-22-2013, 09:29 PM   #14
EveryDayZeeJay
Registered User
1998 ZJ 
 
Join Date: Apr 2013
Location: American Fork, Utah
Posts: 17
Is there some kind of spacer or "gasket" for it. I think I read a few places about something a long these lines. Just don't want to put a new one in wrong, installation looks easy, but what often looks easy sometimes isn't at all.
EveryDayZeeJay is offline   Reply With Quote
Unread 04-23-2013, 11:23 AM   #15
EveryDayZeeJay
Registered User
1998 ZJ 
 
Join Date: Apr 2013
Location: American Fork, Utah
Posts: 17
Quote:
Originally Posted by EveryDayZeeJay View Post
Is there some kind of spacer or "gasket" for it. I think I read a few places about something a long these lines. Just don't want to put a new one in wrong, installation looks easy, but what often looks easy sometimes isn't at all.
Can anyone answer this? Going to test the CPS's resistance today with my DMM, will also order the CPS today if it has any.
EveryDayZeeJay is offline   Reply With Quote




Jeep, Wrangler, Cherokee, Grand Cherokee, and other models are copyrighted and trademarked to Jeep/Chrysler Corporation. JeepForum.com is not in any way associated with Jeep or the Chrysler Corp.