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Intermittent mid-range misfire.

Discussion in 'Stelvio Chat & Tech' started by Revhead, May 8, 2018.

  1. Revhead

    Revhead Just got it firing!

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    I have a 2013 Stelvio NTX 1200. Recently the motor developed an intermittent misfire under acceleration.
    The misfire would come in at around 3500rpm and disappear around 5000 rpm. The engine would then rev smoothly up to 8000.
    I had my local Guzzi wiz check it out and found one of the coils was faulty. Replacing the coil and plugs seemed to remedy the fault allowing the motor to rev out smoothly for the next 100 kms until the problem of misfire returned, although more intermittent than before. Has anyone else experienced misfire problems like this?
    I need to eliminate other causes before open heart surgery to replace ECU.
     
  2. Litch

    Litch Just got it firing!

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    I had something very similar and it turned out to be the sidestand switch, if your problem was briefly cured by changing the coil then this is unlikely to be this n your case unless it was just a coincidence.

    I had suffered it for a couple of weeks (in the rev-range mentioned above which was always when I was accelerating) when I noticed that the sidestand warning light would flicker at the same time. It was then just a matter of cleaning the switch with contact cleaner and it was fine. It did happen again much later and I cured it the same way.
     
    Revhead likes this.
  3. scottmastrocinque

    scottmastrocinque High Miler GT Famiglia

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    I doubt if it was your coil to begin with.

    More than likely, your spark plug boots had been improperly pulled off before and you may have a crack in the rubber where the plug is able to arc out against the engine block. It causes this intermittent symptom like you describe. There are tons of posts here about it you can search, but this one may be of immediate use to you. Good Luck!

    https://www.guzzitech.com/forums/th...io-plug-caps-with-ngk-sb05e.10810/#post-82260


    - Scott
     
    Revhead and john zibell like this.
  4. Revhead

    Revhead Just got it firing!

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    Thanks for this .... I will definitely check it out.
     
  5. Revhead

    Revhead Just got it firing!

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    Sure enough, I can see someone (not me) has poked a hole into the spark plug boot. Looks like a screw driver has been used to pry up the plug boot. Thanks for the heads up on this issue.
     
  6. scottmastrocinque

    scottmastrocinque High Miler GT Famiglia

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    You are most welcome. Good Luck!
     
  7. scottmastrocinque

    scottmastrocinque High Miler GT Famiglia

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  8. theoneandonlymin

    theoneandonlymin Tuned and Synch'ed GT Contributor

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    So as my dash goes blank or inverts,
    I'm going to replace plugs and caps as discussed in other threads on my 08 8v Stelvio.
    Thought that I'd have a wee look at the side stand switch as well. How can you get it off? The back Allen bolt isn't really accessible. In the meantime I've sprayed it with Rockeze to make sure it doesn't stick.
    I've sealed up the speed sensor so hopefully that won't be an issue.
    Cheers
    Min
     
  9. Revhead

    Revhead Just got it firing!

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    After weeks of trying to track down my mid-range misfire, it appears the problem was a faulty crankshaft sensor. The sensor has been replaced and I have had a few thousand kilometers of no more misfire! Fingers crossed.
     
    boscoman likes this.

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