International N9 AFT injector issues

Discussion in 'International Forum' started by PowerstrokeDiesel67, Sep 28, 2021.

  1. PowerstrokeDiesel67

    PowerstrokeDiesel67 Bobtail Member

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    Nov 16, 2019
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    Got a 2015 International N9 throwing the following codes for AFT injector issues:

    3471 7 and 3556 7

    the HCI has been replaced, old one was badly carboned up, new style HCI gasket was installed and verified that the opening was clean. Attempted to do a manual regen and exhaust temps began to rise, but excessive white smoke from the exhaust and a raw fuel smell were noted almost right away. Once the codes came back, the white smoke went away and temps dropped to around 550-600F. I’m assuming my DSI unit is bad but was hoping to get confirmation from HeavyD or one of the other International techs, thanks in advance for the help.
     
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  3. Inderjit

    Inderjit Light Load Member

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    Sep 17, 2017
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    From the troubleshooting manual:

    3471 7 AFT Fuel Doser Valve not responding as expected (page 1134)

    Fault Overview Fault sets when Doser Control Unit (DCU) detects Aftertreatment Fuel Pressure Control (AFTFPC) is not responding as expected. Lamp Reaction Malfunction Indicator Lamp (MIL) will illuminate when this fault is detected during two consecutive drive cycles. Associated Faults SPN 3482 (AFTFEC) or SPN 3556 (AFTFP2) Fault Facts None Drive Cycle to Determine Fault Status Road Test Possible Causes • VREF 5 high resistance • SIG GND high resistance • AFTFP2 circuit high resistance • System Leak

    3556 7 AFT Fuel Injector not responding as expected (page 1287)

    Fault Overview Fault sets when Aftertreatment Control Module (ACM) detects Aftertreatment Doser Injector (AFTDI) is not responding as expected. Lamp Reaction Malfunction Indicator Lamp (MIL) will illuminate when this fault is detected during two consecutive drive cycles. Associated Faults • SPN 94 FMI 17 (FDP) • SPN 3480 (AFTFEC) • SPN 3482 (AFTFEC) • SPN 3479 (AFTFPC) Fault Facts None Drive Cycle to Determine Fault Status Road Test Possible Causes • System Leak • Restricted AFTDI
     
  4. ChuckMartel

    ChuckMartel Light Load Member

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    Jan 22, 2021
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    Before anything else I’d remove the new doser and inspect the poppet and test the spray pattern, especially if it’s a reman.
     
  5. Heavyd

    Heavyd Road Train Member

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    Like mentioned, double check your new injector for spray pattern. You likely have to two problems. 1, if you are getting the fuel smell and white smoke during dosing and the temps are lazy to increase, you probably have a degraded DOC. 2, If you had the same codes before the new injector, I would suspect the DCU is leaking internally. Also make sure you have no fuel leaks externally from the DCU in behind the head over to the injector.
     
  6. PowerstrokeDiesel67

    PowerstrokeDiesel67 Bobtail Member

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    Nov 16, 2019
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    Awesome, thanks for the help. I will pull the DOC and inspect after I verify the proper spray pattern on the new injector. I also have a new DCU to install if needed.

    Can the injector be removed from its mounting block to check spray, or does the entire block need to be removed ?
     
  7. Heavyd

    Heavyd Road Train Member

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    Yes, it can be removed like a spark plug. To check your spray, put a few drops of diesel into it and then use a rubber tipped blow gun at about 40-50 psi. Should produce a nice mist in a cone like pattern.
     
  8. PowerstrokeDiesel67

    PowerstrokeDiesel67 Bobtail Member

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    Nov 16, 2019
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    Awesome, thanks again for the help on this. I’ll post my findings tomorrow.
     
  9. PowerstrokeDiesel67

    PowerstrokeDiesel67 Bobtail Member

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    Nov 16, 2019
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    No fuel leaks found between the DCU and injector. When running the DSI system test, I repeatedly had one section of the test show a “fail” instead of “pass”. After testing spray pattern of the injector I replaced the DCU, ran 2 priming procedures and reran the system test, this time I got all “pass” as a result.

    Started a manual regen where temps got up to 1000F for a while, then slowly dropped off with an active code of 3471 FMI 10 for incorrect AFT dosing fuel pressure showing active.

    Any thoughts?
     
  10. PowerstrokeDiesel67

    PowerstrokeDiesel67 Bobtail Member

    9
    2
    Nov 16, 2019
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    After inspecting the spray pattern on the injector for a second time and finding nothing wrong and running the DSI system test multiple times with no issues, I forced a regen again and it ran for the normal time and completed successfully. Perhaps there was still air in the DCU giving me my 3471/10 code on the first regen attempt?

    Either way, the truck is leaving tomorrow with no codes and a successful regen. Thanks for the help guys.
     
    Heavyd Thanks this.
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