possible bad ECM - what to buy - what is compatible

Discussion in 'Gen 1 & 2 - Electronics & Audio' started by wespiece, Nov 7, 2016.

  1. wespiece

    wespiece SHO Member

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    I have a 98 SHO 3.0 converted into a buggy and I am having an issue where it will die and seems to get flooded out. When I try to restart it, you have to floor it and crank on it for some time, and it does not always refire. Sometimes you just have to let it sit for a few hours and then you just walk up and hit the key and it fires right up. I have replaced the MAF and the TPS.

    I have several codes showing up on the check engine light and most of them show that the ECM has no power. How is this possible if the car is running and driving? I have checked power and the pins are hot. I am down to the point where I think this could be ECM related and would like a model number that is compatible off EBay so I can just replace it cheap as a test. I find plenty of 12A650 ECMs but none that are -AA-MR

    My problem is I don't see the exact model number match to mine. Anybody have any idea what ECM would be compatible or have an idea what else may be wrong?
    [​IMG]
     
  2. Emerald93shoatx

    Emerald93shoatx SHO Member

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    98? Didnt have a 3.0l are you sure its not a 3.4l? Is it the v8 or the v6?.

    Sent from my LG-D852 using Tapatalk
     
  3. AREA 91

    AREA 91 PA SHO SHOP

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    You can use any89-95 non california MTX computer.
    B9B
    B9B1
    LOS
    X2J
     
  4. wespiece

    wespiece SHO Member

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    my total bad - its an 89'
     
  5. wespiece

    wespiece SHO Member

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    the numbers listed above are they the prefix or where are they shown on the label?
     
  6. sperold

    sperold Last to Know

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    You can see the XJ2 on the photo you included in post #1.
    It is not a part number that you use to order the unit from a supplier, but it is the number that identifies the unit you need, and it is used throughout the trade.
    You have the most advanced, most developed software in that unit for a manual shift set up.

    To clear things up, when looking at the list above from area91, the model year of the car, when you go down the list is 89, 90, 91, 92 to 95.
     
  7. Emerald93shoatx

    Emerald93shoatx SHO Member

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    Figured. Just cheking lol

    Sent from my LG-D852 using Tapatalk
     
  8. wespiece

    wespiece SHO Member

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  9. Emerald93shoatx

    Emerald93shoatx SHO Member

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    [​IMG]



    Those are the ecus you can use. But the xj2 can b used in all yeras of the mtx. To my knowledge.

    Sent from my LG-D852 using Tapatalk
     
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  10. Emerald93shoatx

    Emerald93shoatx SHO Member

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  11. wespiece

    wespiece SHO Member

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    Thank you for the info - i will be in search of a cheap X2J - also does anybody do a cheap check on PCM's - just to confirm I'm not crazy! Might be worth it at $25 or so.
     
  12. kevinspann

    kevinspann 87 Octane

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    What codes do you actually get out of it?

    Do you think it could be a possible crank sensor issue? The dying and then refiring and running fine at some point later is a common failure mode when they're in a car.

    Has the engine wiring harness been cut or modified significantly?
     
  13. Emerald93shoatx

    Emerald93shoatx SHO Member

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    Some shops do but not sure on sho ecus..

    Sent from my LG-D852 using Tapatalk
     
  14. sperold

    sperold Last to Know

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    What are the codes you are getting?

    Don't be too quick in buying another ECU, as they usually do not repair themselves, once they fail.
     
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  15. wespiece

    wespiece SHO Member

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    The harness has been modified to remove the relay control box. Other than that its pretty much stock. I have tried clearing the PCM codes and still i get the same codes when checking them via the check engine light. codes are 11-85-19-55-15-56-56-4
    85 is CANP and i don't think it matters - i have a solenoid but cant find the connector to plug it into
    19 is no power on pin 37 & 57 - which i know has power
    55 is no power pin 5 - which i know has power
    15 is no power pin 1 - if this didn't have power it would never run
    56 is MAF input high - i get this code twice
    4 - not sure what this code is - it does not show up on any of the sheets i can find
     
  16. wespiece

    wespiece SHO Member

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    I am open to suggestions here - like I said the buggy runs good but once it warms up if you push in the clutch pulling up to a stop and it dies, it may or may not restart. If it does not restart right away (like in a couple cranks) sometimes it will restart if you go wide open on the throttle and crank on it for a few. If that does not work then you have to just let it sit. When you come back it will fire right up, no pedal input required. With the weird ECM codes and the fact that I cant get them cleared it just makes me suspect the ECM, but I am no expert with SHO motors for sure.
     
  17. kevinspann

    kevinspann 87 Octane

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    An X2J ECU would have 3 digit codes, not 2.

    Which makes your codes

    118 - ECT sensor is/was high or open - an actual problem, either a bad sensor or wiring.

    519 - PSP switch/circuit open - Power steering pressure switch - you could possibly jumper this or plug in a switch that goes to nothing. A non issue either way with your buggy

    551 - Intake Manifold Runner Control (IMRC) solenoid/circuit - are the secondaries plugged in, is the controller on the intake even there?

    556 - Fuel pump relay primary circuit fault - Likely due to the CCRM being removed

    564 - Fan Control (FC) circuit failure - makes sense as you said the CCRM has been removed

    http://www.thorssell.net/hbook/3digit.html
     
    Last edited: Nov 8, 2016
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  18. rubydist

    rubydist Moderator Staff Member

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    I am confident that you are not counting the flashes correctly. Can you post a video so that we can decode the flashing light for you?
     
  19. wespiece

    wespiece SHO Member

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    hey yall may be on to something - wasn't aware of the 3 digit codes. I will get a video of the check engine light just to confirm. What is the ECT? as far as i know everything is hooked up, so whatever it is must be bad. Also what is IMRC - solenoid - again I'm pretty sure its in place and connected. Sorry so vague. Will do more research now that I have a different lead to follow.
     
  20. wespiece

    wespiece SHO Member

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    found one issue ECT is Engine Coolant Temp sensor - i have removed the factory sensor and installed a external gauge and matching sensor. does it mess up the ECM not having this input for reference? figured it was there mostly to trigger the fans and for the dash temp gauge
     

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