2nd Gen R56 Cooper S Gen 2, Engine Misfire

Discussion in '2nd Generation: 2007+ R55 through R61' started by AnneKara, Sep 18, 2011.

  1. AnneKara

    AnneKara New Member

    Oct 3, 2009
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    Hi, My 2010 Cooper S has developed a misfire underload and also during just plain highway driving. It has been to the dealer twice, first time they changed the plugs. Second time they did a ECU update and did the injecter cleaning process. I had had two codes a P0300 and a P0304. Unfortunately things are not better. I have 60k on my S and am rapidly getting upset. The dealer hasn't been a problem, yet, and both times the car ran better for a day then it is right back to the same old bucking misfire. It starts when cold and only slightly improves when warm. Milage seems to be slighly effected. Any thoughts would be of a great help. I am thinking it is a sensor issue ???
     
  2. countryboyshane

    countryboyshane New Member

    Jul 23, 2009
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    Did they already check for excessive carbon buildup in the intake ports and combustion chamber? There are many documented cases of excessive buildup in the intake ports (especially around the valve seats) causing misfire problems. I would check there. 50-60K miles is where most manual transmission R56 S's are seeing their first issues with carbon problems. The automatic's start at around 30K:blush2:
     
  3. AnneKara

    AnneKara New Member

    Oct 3, 2009
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    Gen 2 Engine Misfire

    My service writer suggested that i try a can of BG44K! Well, I did and surprisingly it greatly improve the driveablity of my Mini!! My Mini was much improved within five minutes of driving, and my mileage has improved. The other thing that I noticed was that the idle has smoothed out. I am thinking that the injector cleaning the dealer did only partial cleaned up the gunk and the BG44K finished the job. The other thing the dealer suggested was to go to mid-grade fuel, as at our altitude 6000+ft premium wasn't needed in the Fall-Winter-Early Spring? Anyway, my Cooper S is fun to drive again.
     
  4. Nathan

    Nathan Founder

    Mar 30, 2009
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    Keep notes of all this. Make sure you have the work orders from the dealer to document this issue as it will happen again and again. Since you are past the 50k point you will need all the ammo you can get in case this turns into something more.
     
  5. countryboyshane

    countryboyshane New Member

    Jul 23, 2009
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    Diesel Engineering
    Bloomfield Hills, MI
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    Fuel system cleaners will do a good job of cleaning any buildup in the fuel system especially in injector nozzles and it cleans up the combustion chamber a little bit.

    I still think you have a lingering problem with carbon build-up. The fuel system cleaner doesn't clean the intake ports in a direct injection engine like the N14 engine features. The dealer is probably dodging this because it takes a lot longer time to manually clean out the ports compared to adding fuel system cleaner. MINI USA might not pay them for the work either if they can get by with the easiest solution. They might not have the new BMW special tool for it either:(

    Either way, keep motoring with a smile on your face!
     

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