2001 Cummins N14 rough running/idle

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by mission_creek, May 15, 2021.

  1. mission_creek

    mission_creek Bobtail Member

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    Feb 22, 2021
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    There are periods of time when the engine will run incredibly smooth and quiet. Then it will run rough like it’s missing a little or injector is knocking. Seems to run rough more often now. Would this be a wiring harness issue?
     
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  3. Heavyd

    Heavyd Road Train Member

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    I would suspect aeration of the fuel. This is typically caused by dry rotted fuel lines. Can be intermittent too. Sometimes the cam sensor can start to go bad but not bad enough to log a fault code. Certainly, bad or dirty electrical grounds can cause issues like this too.
     
  4. blairandgretchen

    blairandgretchen Road Train Member

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    A running down the road cylinder cut out test may rule in/out injectors.

    I had a 2001 N14, 1.4 million is still strong with the new owner.

    Replaced injectors, fuel lines, cam and crank sensors. Ran great.

    Always had an intermittent stumble at idle - not sure why.

    A slight miss led me to have a Cummins tech go for a drive plugged in and perform cylinder cut out - weak on 2 , replaced all.
     
    Last edited: May 16, 2021
    John E. Thanks this.
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