Rare 1995 Jeep YJ sahara (stalling problem)

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codycoyote

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My 1995 Jeep Wrangler YJ Sahara Automatic 4.0l straight 6(to the numbers-it is the last one of its kind ever made in canada) its been in my family my whole life. it has around 360k kms but it has been taken excellent care of.
It has a random stalling issue. Ive gone through a dozen mechanics and no one can figure it out. Ive changed out as many parts as i can think of that could potentially be causing this issue. Its not showing any codes either. I have been trying to figure this out for coming up on 5 years now.

I feel like ive gone through all the forums out there.

So the jeep cold starts perfectly everytime, no issues... The jeep runs amazing aside from this problem. Especially because ive replaced so many things.

The Issue-
While driving, you can drive an hour... Or 15 minutes.., then randomly the engine will cut out.
No sputtering, no back firing, no loss of power... Just cuts out randomly?
So then you pull over on the side of the road. You can try starting it again right away, but it will just continue to crank till you kill your battery.
Or you wait 2-5 minutes and it will start up and drive again. The longer you wait, the further you can drive before it cuts out again.

After everything ive done, Im at the stage of thinking it sounds like an over heating issue, but the engine itself remains a normal temperature. Maybe there is a wire thats over heating or a sensor or something that could cut the engine some how.

NEW PARTS ADDED

-Before the problem happened-
Distributor
O.2. Sensor
Catalytic converter
Exhaust manifold
Radiator


1 year after that, a year of no issues. the first engine cut out happened

-After the problem happened-

Fuel filter
Fuel pump (twice, incase the first one was a dud)
Fuel pump relay
Ignition coil
Ignition module
Ignition switch
Oil pressure sensor
Throttle position sensor
MAP sensor
Engine coolant temp sensor
Distributor (incase the one 8yrs ago went bad)
Distributor wires
Spark plugs
ECM!
Auto shut off relay
Crankshaft position sensor
Camshaft position sensor
Battery
Battery wires.

Likely forgot some too
 
Ive already gone through the whole fuel system completely, each fuel system ground cleaned , and if it were a fuel problem... I would have other symptoms than random engine cut outs. No lack of power, no sputtering, no back firing,

I appreciate all inputs! Thank you.
There might be a comment that wont be the answer but could spark an idea or push me in the right direction?
So thank you!
 
Check the wiring harness for the crankshaft position sensor where it goes over the back of the intake manifold, the harness can chafe there and ground out at random.

But really what you're describing is a classic symptom of a bad sensor. When they get hot and the internal pieces expand the circuit opens up, when they cool the circuit closes again. Which means that checking something like the crank sensor with a multimeter can show a good sensor but it could be failing when hot.

I know you said you've replaced the Crank position sensor but if you used anything other than MOPAR, it's not unheard of for them to be bad out of the box. Even a MOPAR branded one has a possibility of being bad.
 
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codycoyote said:
My 1995 Jeep Wrangler YJ Sahara Automatic 4.0l straight 6(to the numbers-it is the last one of its kind ever made in canada) its been in my family my whole life. it has around 360k kms but it has been taken excellent care of.
It has a random stalling issue. Ive gone through a dozen mechanics and no one can figure it out. Ive changed out as many parts as i can think of that could potentially be causing this issue. Its not showing any codes either. I have been trying to figure this out for coming up on 5 years now.

I feel like ive gone through all the forums out there.

So the jeep cold starts perfectly everytime, no issues... The jeep runs amazing aside from this problem. Especially because ive replaced so many things.

The Issue-
While driving, you can drive an hour... Or 15 minutes.., then randomly the engine will cut out.
No sputtering, no back firing, no loss of power... Just cuts out randomly?
So then you pull over on the side of the road. You can try starting it again right away, but it will just continue to crank till you kill your battery.
Or you wait 2-5 minutes and it will start up and drive again. The longer you wait, the further you can drive before it cuts out again.

After everything ive done, Im at the stage of thinking it sounds like an over heating issue, but the engine itself remains a normal temperature. Maybe there is a wire thats over heating or a sensor or something that could cut the engine some how.

NEW PARTS ADDED

-Before the problem happened-
Distributor
O.2. Sensor
Catalytic converter
Exhaust manifold
Radiator


1 year after that, a year of no issues. the first engine cut out happened

-After the problem happened-

Fuel filter
Fuel pump (twice, incase the first one was a dud)
Fuel pump relay
Ignition coil
Ignition module
Ignition switch
Oil pressure sensor
Throttle position sensor
MAP sensor
Engine coolant temp sensor
Distributor (incase the one 8yrs ago went bad)
Distributor wires
Spark plugs
ECM!
Auto shut off relay
Crankshaft position sensor
Camshaft position sensor
Battery
Battery wires.

Likely forgot some too
Click to expand...
DANG!!! That's a lot to change out...
 
I Have the M/T stick shift version of yours.
and the time to diagnose any car that stalls. is when it stalls. hot.
there are many points of failure, on cars. lucky not so many 1995 only one COMPUTER here, and a huge blessing that.

So it stalls hot and fails to restart right>? and as it stalls a fast right foot does not allow you to keep it going.
step 1 is, it stalls and you then test for spark, as we did now for 100 years. Henry Ford and on.

see this 13 year old video of scotty, and checking spark. watch him then do the same on any car that stalls.
and fails to start,.

https://www.youtube.com/watch?v=064Ilsz8Fzg

I presume i can post a video. after all why repeat the same test here, as we did for 100 year, again. I have nothing to sell ever. !

no loss of power..??? no sure what means,, a dead engine is 100% loss off power so you meant I guess, no loss of main 12vdc POWER.



next question,at dead engine.
key ON the CEL lamp must glow or PCM is dead or 12dc power to it or PCM ground is bad,, does it?
then do the key on 3 times trick. make sure code for no DTC errors happens.

crank the dead engine for 5 full seconds
then do this,....
if you get nothing from the PCM (flash codes) the PCM CAPS are bad. (electrolytic caps) or all power pins/grounds to PCM are bad.
also if you think PCM is dead the why not cause a gross error. to force a DTC code to happen.

unplug map conn. and crank /?
if spark is dead we fix that first. cant burn gasoline lacking spark.
the fuel but of PCM see spark dead it cuts fuel hard. hard logic in PCM does that and the ASD drops out.
The PCM ASD drops of for 02 shorts or any device on output of ASD that overloads the ASD the PCM seen that and shuts the ASD down.
that is enough for now.

check spark first. ok? and if spark is dead we work just that to the logicial conclusion every time (not once have I failed to find it)

DTC checks. flash codes.
my personal 95cheat sheet TDC how

PROCEDURES 1995 (below) pasted.
ACCESSING DIAGNOSTIC TROUBLE CODES
A stored Diagnostic Trouble Code (DTC) can be dis-
played by cycling the ignition key On-Off-On-Off-On
within three seconds and observing the malfunction
indicator lamp. This lamp is displayed on the instru-
ment panel as the CHECK ENGINE lamp (Figs. 5 or
6).
They can also be displayed through the use of the
Diagnostic Readout Box (DRB) scan tool. The DRB
connects to the data link connector in the engine
compartment (Figs. 7 or 8). For operation of the
DRB, refer to the appropriate Powertrain Diagnostic
Procedures service manual.

CODES
DTC
12- BATTERY FAILED, OR REMOVED./
55- EOC END OF CODES. FLAG
List of codes/standard meanings:
the CEL must not blink in random fashion ever, or PCM is sick (power bad to it or caps dried out)


11: No ignition reference signal detected during cranking (bad hall effect) OR timing belt?(none) skipped one or more teeth; or intermittent loss of either camshaft or crankshaft position sensor
12: Memory Standby power lost (Battery or computer recently disconnected)
13: No change in Manifold Absolute Pressure sensor (MAP) from start to run
14: MAP sensor circuit open or shorted; voltage too low
15: No speed/distance sensor signal
16: Loss of battery voltage detected with engine running
17: Engine stays cold too long (bad thermostat)
21: Oxygen sensor signal out of range, possibly shorted
22: Coolant sensor signal out of range (or disconnected to set timing)
23: Intake air temperature signal out of range
24: Throttle position circuit out of range
25: Automatic Idle Speed (AIS) motor driver circuit shorted or target idle not reached, vacuum leak found
26: Peak injector circuit voltage has not been reached
27: Logic module fuel circuit internal problem or TBI injector does not respond properly to control signal
31: Evaporator Purge solenoid circuit open or shorted or Evaporator solenoid circuit
32: EGR system failure or Power loss lamp open or shorted (ENDED 1991)
33: Air conditioning clutch relay circuit open or shorted ( Also will show up for rigs without AC)
34: Speed control vacuum or vent solenoid circuits open or shorted(CRUISE)
35: Cooling fan relay circuit open or shorted
36: Wastegate control circuit open or shorted,TURBO. DREAMS
37: Shift indicator light failure, 5-speed (blown bulb) OR Park/neutral switch failure OR Torque converter unlock circuit open or shorted, A-413 4-speed auto
41: Alternator field control circuit open or shorted
42: Automatic shutdown relay circuit open or shorted(OR OVERLOADED)
42: Fuel pump relay control circuit
42: Fuel level unit - no change over miles OR Z1 voltage missing when auto shut-down circuit energized
43: Peak primary IGNITION coil current not achieved with max dwell time OR Cylinder misfire
43: Problem in power module to logic module interface
44: No FJ2 voltage present at logic board OR Logic module self-diagnostics indicate problem OR Battery temperature out of range
45: Turbo boost limit exceeded (engine was shut down by logic module)
46: Battery voltage too high during charging or charging system voltage too low
47: Battery voltage too low and alternator output too low
51: Oxygen sensor stuck at lean position OR Internal logic module fault ('84 turbo only)
52: Oxygen sensor stuck at rich position OR Internal logic module fault ('84 turbo only)
53: Logic module internal problem
54: No sync pickup signal during engine rotation (turbo only) OR Internal logic module fault ('1984 turbo only)
55: End of codes
61: "Baro" sensor open or shorted
62: EMR mileage cannot be stored in EEPROM
62: PCM failure SRI mile not stored
63: Controller cannot write to EEPROM
64: Catalytic converter efficiency failure
65: Power steering switch failure
 
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