DDEC2 problems...missing and falling over iteself for 15 seconds.

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by Jdenney321, Oct 29, 2021.

  1. jamespmack

    jamespmack Road Train Member

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    They insulate them for vibration.
     
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  3. Jdenney321

    Jdenney321 Bobtail Member

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    Yeah any info on the ddec2 from Detroit is kind of a joke, they told me today that "yeah stuff that old isn't really worth our time"
    So I don't rely on Detroit at this point to help its customers.

    The main power going to the ecm looks like a 6pin connector, 2 12v on one side and same on the other side with 2 grounds in the middle, I might be wrong. But the 2 in the middle are black and don't have 12v in it.

    I didn't fool with finding the bad grounds, I just added 4 new grounds from the ecm case to the frame of the truck. I'll find the old bad grounds this winter, but for now I just need this truck back on the road making money
     
    lwlevens Thanks this.
  4. Inderjit

    Inderjit Medium Load Member

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    That 6 pin power connector can be tested with a load. I use a couple
    high/low beam headlights with all 4 filaments hooked up. You would
    need to find terminals that fit the power connector. The grounds could
    be the problem.
     
  5. wilco379

    wilco379 Bobtail Member

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    I have a 98 pete 379 with a 12.7 Detroit in it, been having this problem for months now. the problem is intermittent some days its great some days it acts up, right as you start rolling in the the throttle at lower speed and low rpm "1500 to 1600" it will start to pop and stumble and blow whiter grey smoke out the stacks it smells of raw fuel. does not do it at high way speeds. so far i have replaced the suction lines, filter head, new filter, new fuel pump, new map sensor, check check valve on return line and 0.80 restricted 90 on return. currently pulled all injectors out and re oringing them and putting new cups in, injectors have about 50,000 on them along with the entire motor, any help would be appreciated.
     
  6. Inderjit

    Inderjit Medium Load Member

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    Years ago I ran into a 12.7 Detroit that was doing the exact same thing.
    There were no fault codes either.
    It was because the terminals that connect to the timing sensors had worn
    and lost their grip on the sensor terminals. I replaced both sensors and
    the terminals and it ran properly again. The timing sensors have no
    pigtails so the connector vibrates with the engine.
     
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  7. wilco379

    wilco379 Bobtail Member

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    i guess I'm a little confused on what you mean by they don't have a pig tail? when i replaced the 2 sensors the both have regular 2 pin plugs with a clip.
     
  8. wilco379

    wilco379 Bobtail Member

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    I guess im a little confused by what your saying, when i replaced both of those sensors they were just normal 2 pin plugs with a clip that clipped over the sensors. Are you saying those could be loosing connection?
     
  9. Inderjit

    Inderjit Medium Load Member

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    The connector plugs into the end of the sensor. some engines have a short
    length of wires between the sensor and the connector that plugs into the
    engine harness. That length of wire or pigtail helps reduce the vibration at the connector.
    If the terminals are loose on the sensor pins vibration can cause connectivity
    problems.
     
  10. wilco379

    wilco379 Bobtail Member

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    That makes sense now i will look into that once i get the injectors re set and run an over head on it, thanks for your reply this this has left me scratching my head for months now.
     
  11. Inderjit

    Inderjit Medium Load Member

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    This is going back a few years but Detroit Diesel had an EEPROM stabilizer
    kit for the DDEC-2 ECM. We used to install them when dealing with intermittent
    problems. The EEPROM is "electronically erasable programmable read only memory"
    or the flash memory that the software and parameters are stored on. The EEPROM
    was in a socket that could be unplugged from the circuit board inside the ECM.
    The stabilizer kit held it tight in its socket. I think they were worried the connections
    at the EEPROM could be affected by engine vibration.

    Also give the wires the ten pound pull test at the end near the connectors on
    both speed sensors. I have seen wire break from vibration near where the terminal is crimped on.
     
    Last edited: Nov 28, 2021
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