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Thread: P023D MY08 3.6 TDV8 possible causes

  1. #1
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    P023D MY08 3.6 TDV8 possible causes

    The fault most often occurs while towing 2.5T van on light throttle in slightly undulating country but sometimes doesn't occur for several days and other times occurs repeatedly even when the engine is working reasonably hard. A slight hesitation is felt just prior to the fault occurring to the extent that the occurrence can often be predicted and sometimes avoided, at least for a short time.

    All intake hoses have been replaced, the turbo actuator joints are very loose, no oily residue on the inlet manifold that might indicate a split, the fault still occurs if MAFs or MAPTs swapped and monitoring live values for airflow, sensors, EGR commanded position shows nothing particularly different between sides and nothing immediately prior to the fault that might give a clue as to the reason. The fault has been occurring since chasing an overheating problem which was cured by fitting a new genuine radiator a couple of years ago. There is more black, unburnt fuel smoke on hard acceleration these days than previously. The ECM is not known to have been remapped.

    The vehicle has done 250K and still has the original EGR valves. I suspect that the RH EGR valve is sticky, probably never fully closing and sometimes sticking quite widely open on those occasions when the fault occurs at higher engine revs.

    Any other suggestions?

    TIA Graeme
    MY12 RRV 4.4 TDV8 AB, +LLAMS, +e-diff, +ACC stop/go. Produce LLAMS for LR/RR, Jeep GC/Dodge Ram
    VK2HFG and APRS W1 digi

  2. #2
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    P023D MY08 3.6 TDV8 possible causes

    P023D-21 or -22????

    This is RH side.

    It’s seeing less or more boost than expected. A stuck EGR will certainly make that happen.

  3. #3
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    -22, yes RHS. The fault description doesn't state whether low or high, just exceeds the maximum allowed digression. Nothing discernible watching the pressures and actuator demanded positions but as revs are low so is airflow with the actuators above 75% trying to maximise turbo performance. No change in the graphs until a couple of seconds after the fault occurs so nothing failing, just slowly getting to the point of triggering the fault. EGR actual position graphs both showed 5% which presumably is the closed position, but only of the actuator mechanism, not necessarily the valve itself. That fuel consumption increases when the faults are occurring whether towing or not and that the faults can take a holiday for weeks or occur every few minutes at other times suggests a sticking EGR valve more than a failing turbo. I suspect EGR blanking plates and an EGR-deleted re-map are on the horizon.

    There are no load resistors for the van's LED lights so the engine presumably is allowed to work a little lower in the rev range and the gearbox resists a downshift a little longer but still pulls well until just before the fault. My brother, the owner, doesn't want to have to shift manually all the time even though the fault can mostly be avoided by down-shifting earlier. Load resistors will be fitted with the expectation that the engine won't be worked in the borderline conditions but the root cause needs to be found and fixed.
    MY12 RRV 4.4 TDV8 AB, +LLAMS, +e-diff, +ACC stop/go. Produce LLAMS for LR/RR, Jeep GC/Dodge Ram
    VK2HFG and APRS W1 digi

  4. #4
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    Thanks Graeme

    -22 means over maximum:

    P023D-22

    aka P023D22
    Description

    Manifold absolute pressure (MAP) sensor/right-hand turbocharger boost sensor correlation - signal amplitude greater than maximum
    Meaning

    The turbocharger boost pressure the engine ECU (PCM) is seeing is more than the maximum it was expecting. So the turbo is overboosting.
    Causes

    Intake air system fault
    Turbocharger mechanical fault
    Intake air temperature (IAT) sensor fault
    Mass air flow (MAF) sensor fault
    Manifold absolute pressure and temperature (MAPT) sensor fault
    Exhaust gas recirculation (EGR) sensor fault
    Turbocharger actuator position sensor fault

    Resolution

    Check the intake air system.
    Check the turbocharger mechanical condition and operation.
    Check for DTCs indicating a listed sensor fault.
    Rectify as necessary.
    Using a data logger function, monitor the turbocharger actuator position and command the actuator to 5% pulse width modulated (PWM), then 95% pulse width modulated (PWM) in 5% steps. Check the results. There should be a smooth curve between the minimum and maximum values. If not, install a new turbocharger.
    Clear the DTCs and test for normal operation.

  5. #5
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    Thanks Mike, that's more info than given in the LR WSM for the engine which I thought was already extensive, although not particularly specific, more like an automotive standard definition/description.

    However over maximum appears to refer to the correlation as per a formula between the pressure indicated by the MAP sensor and the turbo actuator position rather than boost is over maximum, but you may have other experiences. The loose actuator rod joints could allow the turbo vanes to overshoot but as the vanes would be pushing against the airflow I would expect the vanes to not open as far as required rather than further than required, possibly not creating enough boost and thus possibly the cause of the correlation fault.

    As the common cause for the fault is a boost leak, either from a split hose or split manifold, I expect that the manifold pressure is less than it should be, not more and therefore having ruled-out faulty MAP and MAF sensors, either the turbo is under performing or boost is leaking. Actuator arm service kits are available which were introduced because joints were seizing, not becoming excessively loose.

    Edit: Inlet port de-activation was disabled for one test by disconnecting the electrical connector on the solenoid that controls the vacuum to the 2 actuators, with only a possible slight reduction in smoothness at slow speeds on light throttle but no de-activation port faults were recorded. The default position is ports are not de-activated.
    MY12 RRV 4.4 TDV8 AB, +LLAMS, +e-diff, +ACC stop/go. Produce LLAMS for LR/RR, Jeep GC/Dodge Ram
    VK2HFG and APRS W1 digi

  6. #6
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    Another possibility is a faulty actuator sensor. I had considered that the reference to a possible actuator position sensor fault was a generic reference but the actuator motor presumably has an inbuilt sensor to indicate the position of the actuator arm, rather than an external sensor for the arm. However the loose joints may cause sufficient variance between the commanded and the actual position of the arm on the turbo itself.
    MY12 RRV 4.4 TDV8 AB, +LLAMS, +e-diff, +ACC stop/go. Produce LLAMS for LR/RR, Jeep GC/Dodge Ram
    VK2HFG and APRS W1 digi

  7. #7
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    What did you end up doing to fix the issue Graeme?
    Or is it still ongoing?

    My L320 TDV8 has started to do the same thing - occasionally and intermittently
    on uphill slopes usually.

    Throws the following fault code:
    PCM-Engine TDV8 3.6L P023D-22 (68) Manifold absolute pressure - turbocharger/supercharger boost sensor A correlation General signal failure - signal amplitude>maximum

    Might start by swapping the sensor for each bank and see if the code changes.

  8. #8
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    The left inlet manifold had a small split with a new one currently being fitted. Presumably and hopefully the fault won't occur now.
    MY12 RRV 4.4 TDV8 AB, +LLAMS, +e-diff, +ACC stop/go. Produce LLAMS for LR/RR, Jeep GC/Dodge Ram
    VK2HFG and APRS W1 digi

  9. #9
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    Oh wow. interesting.
    A split in the actual manifold itself, rather than the flexible hoses?

    Did you pump smoke into the intake system with a smoke machine to find it, or was it obvious enough to see?

    I'll have to have a close look at mine.

  10. #10
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    Soot had for some time been emerging from under the metal cover. The manifolds are known to split. His vehicle is almost entirely used for towing, mostly his van but sometimes his camper or car trailer.
    MY12 RRV 4.4 TDV8 AB, +LLAMS, +e-diff, +ACC stop/go. Produce LLAMS for LR/RR, Jeep GC/Dodge Ram
    VK2HFG and APRS W1 digi

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