1996 ZJ stalling and dying problem

[starskieandgut]

So I have a 1996 ZJ 4.0 I6, couple weeks ago I noticed it starting to "bog" down randomly for a week or 2 and now it will die randomly. I've been told possible Crank sensor (don't think it is because, it doesn't have the same symptoms has it had 3 years prior when I had it swapped), ignition coil, or fuel filter could be causing it. Now another buddy was looking at it and noticed this thing "ticking" after the Jeep warmed up for a few seconds, and he believes I might be losing pressure somewhere. So my question is what is this exactly, is it normal for it to "tick" and any other suggestions would be very much appreciated.

https://imgur.com/a/vkFoIWt

Thanks in advance

 

[macgyvr]

It's not a crank sensor, it wouldn't run at all if that wasn't working.

The IAC can get dirty and or worn out, and cause it to die at idle.

4.0's are notorious for a tick, but if it gets worse it could be a loose or broken flex plate and at worst a broken piston skirt.

I would check/clean/replace the IAC. You could also do a compression check to see if there's anything going on with the cylinders as far a losing pressure.

I've had more fuel pumps go out with the pump loosing pressure between starts and taking a couple of times to start rather than it quit while running...but anything is possible. I believe that the "fuel filter" is internal to the fuel pump.

mac 'let us know what you find out' gyvr

 

[Ralph77]

That is not entirely true of the CPS. They can experience thermal failure.
In my '00 XJ it would start right up but then stall when it reached operating temperature.
And stall like you shut the key off. No codes or pending codes either.
When it first started doing it the Jeep would start right back up. Might stall again or maybe I would get to where I was going. But after about a week it got worse.

As far as the ticking goes that picture you showed is your purge solenoid. It is supposed to tick so.........

 

[starskieandgut]

So here's and update: Changed the fuel filter, and nothing changed, cleaned out the throttle body and cleaned the IAC as well. After cleaning, and changing the fuel filter, driving it felt a lot better. After I cleaned the throttle body, it ran great while i let it idle in the driveway for 30 min, drove it 2 miles around and nothing. Later that night went to the store about 5 mile away, still nothing until I returned to my Jeep and it cranked over, started and died instantly, crank again, started and died instantly. Give it 5 min, started it up and made it home, while it bogged on me a few times...

 

[Eddy_AL]

4.0’s are notorious for cooking the coil mounted to the engine block. When they go, no codes, just won’t crank. You might be in the leading edge of its death.

Also, how old is your catalytic converter? You could be seeing enough bad stuff come through that the O2 sensor is cutting the fuel back too lean.

Have also seen weird O2 failures that didn’t throw codes but shut down the XJ.

I’d start with a new coil.


Sent from my iPhone using Tapatalk Pro

 

[OverlandZJ]

ZJ's are also notorious for stalling with loose connection at the ECU. Start it up and just wiggle it a little bit to test.. bumps on the road can cause this stalling if loose. Cheap fix is remove, dielectric grease and a few zip ties pulling connector tight.

I'd second the cat recommendation also.

My 98 had a stalling issue once, turned out to be ground to body at inner fender by battery.

 

[DZABYK]

Hi Jeepers!

VEEERY SIMILAR ISSUE..

All of this concerns a 1998 GC 4.0 LTD, about 83,000 miles.

BTW I've owned this Jeep for eight yrs and, except for a regular maintenance, never had any problems with it.
Love the car..

NOW I'm really STUCK.. as it comes to the stalling issues I'm having these days.

Believe me, I have gone through various threads on this forum (and YTB) but must say I'm still not sure what the problem is.

For about a month now the Jeep has been randomly stalling on me, particularly at low RPM (stop, red light.., NEVER at full speed!),
then the RPM drops down to about 500 RPM.. and I know it's going to shut off in a few seconds.! And it IS!
And.. after a few seconds (usually) starts right back up.. like nothing has happened!! And goes and goes.. until the same happens again..
NO CHECK ENGINE or other warning light!
Tried the OBD check.. no code.

There's NO regular pattern to it.. engine cold, warm, hot.. Just happens.

So, I figured let's start with the usual culprits:

1. Took off the thottle body, cleaned it thorougly (not much carbon deposits anyway..), perfect condition..
2. Replaced all the three sensors, MAP, IAC, TPS..
3. New distributor cap + rotor
4. New spark plugs + wires
5. Cleaned/checked all relays and possible connectors, fuel pump, ASD..
6. Checked the battery terminals/ charge/ OK

Removed the ECM (PCM) computer.. just to check for any visible damage etc. Everything seems to be OK.
No loose connections, oxidations.. etc./ sprayed w contact cleaner
BTW mine doesn't come apart with just unscrewing a few TX bolts like in some previous PCMs. Totally sealed.
Have tried to wiggle the PCM connectors while the engine running.. Nope, didn't die..

After the last stall (about a week ago).. Tried to crank it over and over, spraying carb cleaner (all I had) to the intake.. and nothing.. DEAD.
One weird situation happened. At one point ALL relays started to click like crazy!! Then never again.

I had it towed to my place.
Recharged the battery over night, put in in..
AND.. the Jeep started right up, steady idle, smooth...

Every day I come by to start the Jeep up.. NO PROBLEM!! Purrs like kitten.. Steady RPM, no hick ups..

The next thing that comes to my mind is obviously the fuel pump/filter.
I can hear the fuel pump engage/prime the fuel rail.
I'm gonna check the fuel pressure asap..

As I expect, I should probably replace TPS, CMS, the coil..
and about a hundred of various components until I have found a loose ground wire, right??!!

If you are one of the Jeep (ZJ 4.0) owners experiencing the same issues, please share.

We love our Jeeps and want them keep running as long as possible..!)

Thank you.

dzaby is offline
https://www.jeepforum.com/forum/newreply.php?do=newreply&p=41101487

 

[Anak]

Reminds me of the battle I had with my GTA. I would drive it somewhere, park, come back and it wouldn't start. Get it towed home and it would start just fine. Drove me up the wall because I couldn't diagnose a problem that wouldn't present itself when I had the resources at hand to chase it down.

Finally it got bad enough that it misbehaved at home. It was when I was playing with a Noid light, going through injector by injector that I discovered it would start and run if I disconnected a certain injector. Somehow one injector managed to pull off an intermittent short that would pull down an entire bank of injectors (batch fire system).

That isn't likely to be the issue you are facing, but the type is worth considering. Figure some windings in a coil of some form (could be a relay, or an injector, or the ignition coil) that are on the verge of fully shorting out, but for now are only doing so when there is a bit of heat/resistance to compromise that bit of shellac that counts as insulation, but once the windings cool off the insulation works again.

 

[Anak]

Another thought: The instance of all the relays acting up at once could be a valuable clue. I would look into both the positive and negative supply leads for the PDC. Could be their common ground that is in poor condition, or it could be something like the fusible link to the alternator. The wiring schematics in the FSM might be useful here, but if you don't have those you can still probably track the large conductors visually. They shouldn't be very long. Everything should be up in that front corner.

 

[DZABYK]

Hi Anak

I TRULY appreciate you trying to help me w my issue (driving me NUTS!).
I have ordered the usual stuff (new coil, crank/cam sensors..), it should arrive shortly.
Just to eliminate possible culprits and for peace of mind that these parts are brand new.

As you suggest (thank you!), I'm also going to check all the leads for PCM. Loose/corroded/oxidized.. etc ground can be a real bitch!

UPDATE: Also, today I decided to do a little test. I let the Jeep idle for awhile just to see if the problem occurs without the car moving, running over bumps, simply rule out any vibrations..

Guess what! It started right up, no problem there. However, when the engine reached the operating temp.

I noticed some slight misfiring.. THEN the RPM needle started to flutter.. and the engine just DIED!

And after a little longer than usual cranking.. started right back up.. like everything was absolutely normal..

I'm no expert but "logically" my problem might be related to temperature. Some say that the coil is mounted onto the block.. therefore it gets a lot of "beating" from extreme temp. changes and eventually the insulation gives up..


What are your thoughts on this??

Many thanks in advance,


DZABYK

 

[DZABYK]

Hi Anak

I TRULY appreciate you trying to help me w my issue (driving me NUTS!).
I have ordered the usual stuff (new coil, crank/cam sensors..), it should arrive shortly.
Just to eliminate possible culprits and for peace of mind that these parts are brand new.

As you suggest (thank you!), I'm also going to check all the leads for PCM. Loose/corroded/oxidized.. etc ground can be a real bitch!

UPDATE: Also, today I decided to do a little test. I let the Jeep idle for awhile just to see if the problem occurs without the car moving, running over bumps, simply rule out any vibrations..

Guess what! It started right up, no problem there. However, when the engine reached the operating temp.

I noticed some slight misfiring.. THEN the RPM needle started to flutter.. and the engine just DIED!

And after a little longer than usual cranking.. started right back up.. like everything was absolutely normal..

I'm no expert but "logically" my problem might be related to temperature. Some say that the coil is mounted onto the block.. therefore it gets a lot of "beating" from extreme temp. changes and eventually the insulation gives up..
What are your thoughts on this??

Many thanks in advance,

DZABYK

 

[Ralph77]

Reread Post #3.

 

[DZABYK]

Thanks for yr prompt reply, Ralph77.


Sure, I've read ALL the posts here.
So you bet on CPS then.. Good to know.


See, even though I think I'm mechanically inclined.. I simply HATE electrical issues (can't see them, right?). I'd rather have a broken a-arm or something.. that I can see and fix..


Anyway, as I mentioned in my post, as soon as the parts arrive, I'm gonna replace all of them.. and we'll see how the Jeep behaves then!


THX again


Dzabyk

 

[DZABYK]

UPDATE: Today i borrowed some cheap OBD2 scanner just to see if there are any stored codes.


This is what I got:


P0340 - Camshaft Position Sensor "A" Circuit
- Vehicle Area: Powertrain (P)
- Area of Vehicle System: Ignition System or Misfire
- Controlled by: ISO/SAE Controlled Code (Core DTC)
- Controll Unit: $D1 - Reserved for manufacturer-specific tasks

P0320 - Ignition/Distributor Engine Speed Input Circuit
- Vehicle Area: Powertrain (P)
- Area of Vehicle System: Ignition System or Misfire
- Controlled by: ISO/SAE Controlled Code (Core DTC)
- Controll Unit: $D1 - Reserved for manufacturer-specific tasks


NO Pending Diagnostic Trouble Codes (DTC) (Mode 07)
NO Permanent Diagnostic Trouble Codes (DTC) (Mode 0A)



I should be getting the sensors on MON but I have a feeling that just replacing the CAM sensor won't do. I think it's time to inspect all the related wiring..


Thanks for any advice from all of you more experienced in these wiring issues!


DZABYK

 

[Anak]

Hi Anak

As you suggest (thank you!), I'm also going to check all the leads for PCM. Loose/corroded/oxidized.. etc ground can be a real bitch!

Just to be clear, the connections I am suggesting you pursue are not the ones for the computer (ECM--engine control module) but rather for the PDC (Power Distribution Center). The PDC is the box containing the underhood fuses and relays. I expect it is over on the passenger side fenderwell near the battery.

My thinking is that if all those relays went off and back on all at once they must have all lost power simultaneously. I think the simplest path to that scenario is to either lose positive power or ground. So those are the two leads I would be trying to follow.

Now, that said, I find it a bit unlikely that those would be temperature related. There may be more than one issue at play here. From your description of what occured today I would be more focused on such things as the CPS and the ignition coil. Both of those could have failure modes that match your symptoms.

As a side note I have found that life is much simpler if you slot the holes for the CPS and carry a spare that also has slotted holes. Access to the bolts for the CPS is less than ideal, and some folks have had the misfortune of dropping one of the bolts down into the bellhousing. If you slot the CPS you no longer need to fully remove the bolts and thus are not likely to drop one of them and create a new problem. And you no longer have the challenge of trying to start the bolts in their poorly accessed location. Of course this only really works if you also carry a slotted spare. Just a tip.

 

[DZABYK]

Thank you again, Anak


I'm working on the car as time allows.. step by step.


So far I have replaced the coil, inspected and cleaned the leads to PDC, checked all fuses and relays.. Thoroughly cleaned the ground next to the box and visually (I know..) checked all critical harness points for possible exposed shorting wires..


The next task will be replacing the cam sensor (easy) and the crank sensor (hassle).

Most people do it from underneath but I have found a video where the guy does it from the engine compartment (pass. side) by temporarily removing some stuff in order to get access to this sensor here:


https://www.youtube.com/watch?v=yX0ljCBydsU


He is working on a '95 GC. I'm affraid, I have a slightly different setup ('98 GC). Don't know anybody with a GC that I could compare it with.
Since I have no access to hoist nor have a 50" ratchet multi-extension, I'm considering this option.


Any suggestion??


Thanks in advance.. and have a great day!


Dzabyk