Randomly dies

Discussion in 'Domestics' started by Chuck, Dec 17, 2017.

  1. billr

    billr wrench Staff Member

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    It may not have an actual wheel on the crank with a sensor down there, but it must have a CKP signal to run the EFI injectors. That signal will be coming from the dizzy, if there is no real crank wheel, but it's function is the same (just not as accurate or as many functions).
     
  2. Chuck

    Chuck Sr. Member

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    Could it possibly be part of the ICM?
     
  3. billr

    billr wrench Staff Member

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    Sure, it could be. It could be hard to prove, even if you are fairly good with an electrical multimeter; so swapping in a new (or at least a different) ICM may be the most practical approach. Many of the electrical possibilities here could be hard to catch as they are intermittent. That's why I had you chasing the FP first, it is much easier.
     
    Last edited: Dec 24, 2017
  4. nickb2

    nickb2 Wrench. I help when I can

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    Yeah, you are right, there is no specific crank sensor, but this IS a system that needs to know if engine is turning/running to allow fuel pump continuity. This ECM uses the ESC/T and ICM and other various parameters to determine timing and also to control fuel pump and other strategies. Signal for that will come from the distributor portion which houses a pick up coil, and usually in this era, a 4 tooth reluctor for the pick up, the ICM as you know is in there also.

    This was the beginning of our modern era thinking in regards to engine control algorithms.
     
    Last edited: Dec 26, 2017
  5. nickb2

    nickb2 Wrench. I help when I can

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    I just had a thought, this also has a very important ESC/knock sensor module. This could also be a culprit of your symptoms.

    That usually induces a code 43, but in your case, you just have a code 12. But since it is intermittent, and the ECM of this age cannot be as today in regards of sophisticated algorithms by way of giving you circuit performance codes and such.

    Try tapping the knock sensor and or the ESC module to see if they stall out the engine. May give a indicator that that portion of the ignition system is faulty. The ESC module will be on a bracket mounted to rear of engine. Blue wire is your knock signal.
     
  6. nickb2

    nickb2 Wrench. I help when I can

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  7. Chuck

    Chuck Sr. Member

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    Sorry I haven't replied in a couple days. I changed the ECM last night and have been driving for most of the day, without a hitch....so far. Being carefully optimistic. Sweet video.
     
  8. Chuck

    Chuck Sr. Member

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    UPDATE: Wanted to let everyone know since replacing the ECU I haven't had any issues yet. Hopefully that's what fixed it. Wanted to say thanks to everyone for the help, and if It happens again I'll have a good idea about where to start looking. Thanks again.
     
  9. nickb2

    nickb2 Wrench. I help when I can

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    Thx for the update, I kind of knew it was going to finish this way, but it is better you came to that conclusion yourself.

    Again, thx for update. That is our paycheck here.
     

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