PX9 Knocking and black smoke

Discussion in 'Kenworth Forum' started by BoxCarKidd, Nov 27, 2020.

  1. BoxCarKidd

    BoxCarKidd Road Train Member

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    2013 T370 Ser# 407056. PX9 300 # 73550812
    Engine at idle would periodically start skipping ( misfiring ), knocking like a bad rod bearing and the piston is hitting the head. Some white-gray smoke at times but usually black. Then runs smooth, clears up and repeat.
    Narrowed it down to #4 and replaced injector. Is runs the same.
    Misfire is pretty steady around 1300 but never happens around 1900 RPM.
    Any ideas, thoughts and or experience appreciated.
     
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  3. pushbroom

    pushbroom Road Train Member

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    Any updates?
    I have found valve train issues in them before.
    Measure the pushrod travel to check for a bad cam/ follower?
     
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  4. BoxCarKidd

    BoxCarKidd Road Train Member

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    Checked harnesses between ECM and rocker cover as well as rocker cover to injectors with OHM meter, OK. Powered a headlight through the same wires,OK. Swapped the injector harnesses, each does two cylinders, with no change. Checked all power and grounds we could find with no faults. Valve clearance is OK. Made a compression gauge and tested #4 and #1 while cranking. #4 was 400 and #1 was 410. Not 100% sure how accurate that old 1500 Lb gauge is but did not see 10 lbs as a deal breaker.
    Thanking it is an ECM problem.
     
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  5. QUALITYTRUCK

    QUALITYTRUCK Road Train Member

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    That's a Cummins ISL CM2350 engine. I will check tomorrow at the shop to see if I have a tester ECM. I will ship it to you if you want. If I have I will load current calibration and ECM template for you so you just have to plug in.
     
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  6. BoxCarKidd

    BoxCarKidd Road Train Member

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    Greatly appreciate your offer and almost cannot believe it.
    Sounds like you are very talented with special tools. Thanks for your offer and all the good posts you made helping me and other people.
     
    Last edited: Dec 8, 2020
  7. QUALITYTRUCK

    QUALITYTRUCK Road Train Member

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    You are welcome. I will pm you.
     
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