Cummins n14 injector issue

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by Kenllah, Feb 1, 2021.

  1. Kenllah

    Kenllah Light Load Member

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    Pressure gauge installed. Pressure is solid during entire range of operation. Ran truck from a bucket of fuel looking for any air bubbles on the return line or performance changes. All stays the same, slight miss. Now I'm getting insite messages that the "ecm detects conditions in which the cylinder cut out test should not be run"
    It's looking like ecm related. Not sure what else to test/check
     
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  3. mile marker 27

    mile marker 27 Road Train Member

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    What was your range of fuel pressure?
     
    Kenllah Thanks this.
  4. Kenllah

    Kenllah Light Load Member

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    Appx
    127psi at idle and more than that depending on accelerator position appx 145psi at 1300rpm I think it was. Pressure was rock solid at steady rpm. I was hoping to see in bounce around during the miss but it never did.
     
  5. Kenllah

    Kenllah Light Load Member

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    Did some more testing with insite and a fuel pressure gauge.
    Fuel pressure bouncing from 120 psi to 130psi at 900rpm pto speed

    Appx 135 +- 2psi @ 1091rpm

    126psi at idle +-1psi
    Initiate cylinder cutout test
    135psi +-3psi rough idle no #4 injector response

    Accelerator based cut out all cylinders 85-89 rpm difference EXCEPT #4 at only 11RPM difference.

    125psi @ idle after test slight miss no smoke unplug #4 injector and she stumbles
     
  6. Kenllah

    Kenllah Light Load Member

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    As a follow up I ended up sending the ecm off for testing to DSO Industrial. Exceptional service and very fast. Injector drivers in the ecm was my problem. I have all the tech manuals for this engine as well as cummins insite. It is kind of difficult because of the possibility of bad reman injectors. You can waste a lot of time and money playing swap the injector. I even hooked my injectors up to an oscilloscope to watch the waveform and they all looked good. I guess the timing from the drivers was just off a bit. There was also a ticking in the overhead that I could never get to stop no matter what I tried. That has also gone away with the new ecm.
     
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  7. harryjoy

    harryjoy Bobtail Member

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    Mar 12, 2015
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    Thank you for following up and letting us know what you found.
     
    Kruse Family Farms Thanks this.
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