02 liberty 3.7 dies intermittantly - HELP! I'm out of ideas...

Discussion in 'KJ General Discussion' started by LibertyCentral, Apr 14, 2019.

  1. LibertyCentral

    LibertyCentral New Member

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    I have an 02 liberty, with 3.7 and auto. I've rebuilt the motor, had the trans rebuilt and a lot of other replacements/repairs back in early 2018. It ran great for a year or so.

    This winter, around the time of severe cold, I had to replace the battery. I also ended up putting it on a charger/booster unit to get it started. I only mention this due to the approximation of the time the issues started. I can't say for certainty the battery replacement was the exact time this issue started but its near.

    What happens: I drive the jeep, no determined amount of time and suddenly it dies. Sometimes it starts right back up, other times it takes a few minutes of sitting before it starts up again. It will crank over fine just not fire.

    Things I have tried for isolation:
    -Fuel pressure - Good when it dies, stays consistent at about 50psi even when it has to sit.
    -I have a viper remote start/alarm system. Pulled the fuses for this in case it was defective. No change
    -replaced the PCM thinking maybe I fried it with the battery boost/replacement - no difference
    -had to replace the TPS, had thrown a code but I think it was a victim of when it failed and I pumped the pedal trying to get it to respond. I broke the old one trying to remove it for inspection.
    -wiggle test on various sensors/wires
    -replace the oil pressure sender, due to leakage (oil light does not come on prior to fail)
    -swapped the ASD relay - no change.
    -No codes are set by this event. I have had some codes in the past but these have been present when it ran ok.
    They are:
    P0442 - evap small leak
    P0445 - evap gross leak (hoses by tank need replaced)
    P0734 - gear4 incorrect ratio. no idea why this pops up, it runs fine
    I've had a code 18 and some other bus related error but that was a one off and not at the time of the issue.

    When it dies, it can be sitting at a light, driving highway speed, driving city speeds, basically no pattern to it. In all cases the engine was warmed up so it should be in closed loop.

    In desperation I took it to a shop for further diag and they put about 90 miles on it over 2 weeks. It ran perfect for them of course. I got it back, one trip to the store and it starts the dying issue again.

    Other times I can drive for hours and it never happens.

    I'm lost on this one, if anyone has ideas on what to try I'd love to hear them. I've debated replacing the cam and crank sensors but if they were faulty I'd expect a code logged to them as well. The other thought I had was to jumper the ASD relay to see if it will run through whatever issue it has and throw up a code.
     
  2. HoosierJeeper

    HoosierJeeper Gold Supporter/Admin Staff Member Administrator

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    Does it sputter out and die? Or just flat out abrupt die? I'm wondering if you have a bad ground that's just killing it.
     
  3. dillon

    dillon New Member

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    i have a hunch it's crank sensor but no codes doesn't back up my hunch unfortunately...
     
  4. LibertyCentral

    LibertyCentral New Member

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    Thanks for the feedback so far!

    It does not sputter, it flat out shuts off. Like a key off. One second running fine, the next nothing.

    I also considered the grounds, they look ok, and the shop also verified they were ok. But, its a good thought, I'll double check them again.

    Crank sensor came to mind for me as well, but due to lack of codes I'm not convinced thats it either. It may be worth just replacing it anyway to remove doubt but I hate to get into "throw parts at it" mode.
     
  5. Billwill

    Billwill Full Access Member

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    Could be the Cam or crank sensor or a wire shorting to chassis sometimes or a bad pin in a connector.

    It could be voltage related. Plug your multimeter into the front cigar lighter/power output so you can monitor the battery voltage while driving. I had several wiring problems that would cause the voltage to rise up to 17 volts at which time the engine cut out...2002 Export CRD!

    This was usually initiated by me doing something...switching on the front wipers would make the voltage slowly rise...switching on the aircon etc. By the time I ended a long trip on the open road my battery had boiled itself to destruction.

    Difficult to find such a problem but worth checking the voltage while driving.
     
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  6. dillon

    dillon New Member

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    I had an old explorer that would cut out if i put brakes on going downhill. the wire to crank sensor would shift forward and short out on a pulley and the truck would shut down. no codes.