N14 missing at 1500 to 1600 RPM

Discussion in 'Trucks [ Eighteen Wheelers ]' started by AUSSIE DAVE, Sep 18, 2012.

  1. AUSSIE DAVE

    AUSSIE DAVE Road Train Member

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    Feb 21, 2010
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    A friend of mine has a N14 that is missing at around 1500 to 1600 rpm. No fault codes as such, have checked all injectors and solinoids, engine position sensor, injector hold down clamp, but all is good. Any ideas ?
     
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  3. Daz

    Daz Bobtail Member

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    Sep 18, 2012
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    Broken injector spring.
     
    AUSSIE DAVE Thanks this.
  4. AUSSIE DAVE

    AUSSIE DAVE Road Train Member

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    Thanks I'll check that
     
  5. Daz

    Daz Bobtail Member

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    Sep 18, 2012
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    Use an infra-red thermometer on the exhaust manifold to see which pot is colder after making it miss for a while, if that's sounds too expensive a screwdriver makes a great stethoscope.
     
    AUSSIE DAVE Thanks this.
  6. bender

    bender Road Train Member

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    Don't Kid Yourself
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    Just to add so that it isn't overlooked; The injector plunger is two pieces that are swedged together with a rubber sleeve between the two parts at the swedge. The swedge joint can become loose and allow the plunger to slip in and out causing intermittent misfire. This sometimes causes a ticking/tapping noise when it gets bad enough, but will usually cause a dead miss at that point.
     
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  7. AUSSIE DAVE

    AUSSIE DAVE Road Train Member

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    Feb 21, 2010
    OZ - Brisbane
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    Thanks bender, great info

     
  8. AUSSIE DAVE

    AUSSIE DAVE Road Train Member

    1,032
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    Feb 21, 2010
    OZ - Brisbane
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    Thanks, it's a intermediate miss, don't think it will show up with infra red thermo, . But will check it out.
     
  9. Daz

    Daz Bobtail Member

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    Sep 18, 2012
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    My Fleet Liner did exactly that. Took ages to demonstrate to the workshop boys, it normally did it after a bit of lugging or sometimes from a cold start.
     
  10. Offroadjack

    Offroadjack Light Load Member

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    Jun 19, 2012
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    Did u ever figure it out?
     
  11. Offroadjack

    Offroadjack Light Load Member

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    Jun 19, 2012
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    Mine did that when a injector got weak and then again when it was out of
    Adjustment
     
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