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Rough idle on hot start

Discussion in 'Engine, Drivetrain, Fuel and Exhaust' started by dvarley, May 28, 2017.

  1. dvarley

    dvarley Senior Member

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    Joined:
    Aug 4, 2004
    Location:
    Loire Valley, France
    Your Mercedes:
    E 320 T CDI
    My 320CDI IL6 has developed a problem when the engine is hot and restarted after stopping for a few minutes. The engine shakes like a misfire, but after driving off and getting up to speed, it is okay and will idle fine. It seems worse when the outside temp is 30°+. It shows no faults and has had the mountings replace a year ago. I also get the common knocking noise at 1500 - 2000 revs when hot. I noticed the hot starting problem after filling up with supermarket fuel. Could this be the culprit? Where possible I use Total Excillium, which the car seems to like. Are there any other tests I can do to pinpoint the problem?
     
  2. John Laidlaw

    John Laidlaw Senior Member

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    Your Mercedes:
    W212 E63 ///AMG V8 Biturbo Volvo XC90 2018
  3. OP
    dvarley

    dvarley Senior Member

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    Joined:
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    Location:
    Loire Valley, France
    Your Mercedes:
    E 320 T CDI
  4. John Laidlaw

    John Laidlaw Senior Member

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    Maybe an issue with the CPS (Crank position sensor) but it needs hooked up to a Star diagnostic first I guess to eliminate the obvious stuff
     
  5. OP
    dvarley

    dvarley Senior Member

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    Your Mercedes:
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    Star shows no problems, but the idle was okay when it was plugged in. It only does it just after a hot start and then it is okay until it is switched off and restarted before it has cooled down. CPS was replaced a year ago as it was faulty.
     
  6. Steve@Avantgarde

    Steve@Avantgarde Forum Supporter Authorised Forum Supporter

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    Your Mercedes:
    Mercedes-Benz C32AMG, SL55AMG, C320CDI Sport Edition Estate and SLR McLaren Coupe Roadster.
    Nothing to do with the CPS.

    Sounds like a fuel issue, possibly injector nozzles or quantity control valve..
     
    om613 likes this.
  7. OP
    dvarley

    dvarley Senior Member

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    Your Mercedes:
    E 320 T CDI
    Star shows a fault. P0100-016 B 2/5 (hot film mas air flow sensor) plausibility 1. Air flow low at lower range of speed. Does this suggest that I need a new sensor?
     
  8. OP
    dvarley

    dvarley Senior Member

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    Your Mercedes:
    E 320 T CDI
    [​IMG]

    I have just changed no 6 injector for a reconditioned one from a German supplier. Car back to normal. No tapping noise and fuel economy back to normal.
     
    Taffy7hfa, bembo449 and om613 like this.

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