2nd Gen R56 Cooper Most liked posts in thread: Misfire Cylinder 3

  1. MCS02

    MCS02 Moderator
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    Jul 31, 2009
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    Hi and welcome to MA!
    You said you swapped the coil packs and the misfire did not move with the coil pack, did you try swapping plugs? Which valve seat dropped, was it number 3?
    Warm up the engine and do a compression check with it hot and see if it is different than when it was cold on number 3 cylinder. Off the top of my head all I can think of is ether when it gets warm something electrical is breaking down or once warm there is a compression leak.
    I am sure you have but recheck all the wires make sure they are clean and plugged in good. I don't think it could be in the timing.
    Please let us know what you find.
    Sorry I know this is not much help
     
  2. dk85

    dk85 New Member

    Jan 3, 2018
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    Re:

    Thanks, and thanks for the reply.

    Yes I have swapped the spark plugs around and it is still in cylinder 3. It was the #4 cylinder that the valve seat dropped. I will give the compression test when its warmed up a try. I did today buy a new fuel filter that I am going to replace as soon as it comes in the mail. Either way I'm sure it needs a new fuel filter.

    There is one more thing that I noticed that I did not put in the first message which is pretty major. It was stupid of me not to include it.

    It only Misfires at idle. It runs fine otherwise. I have a diagnostic tool that allows me to view all the misfires when running.

    Thanks Again.
     
  3. MCS02

    MCS02 Moderator
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    That could be a VANOS solenoids. I know you replaced it but they can cause misfire at idle after warm up. I have had new parts turn up bad so don't rule it out. Re check your vanos make sure the plug and wires are ok and clean.
     
  4. Rockster

    Rockster New Member

    Jan 5, 2018
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    Not at all familiar with Mini engine but I know in some cars with a variable intake valve lift feature -- a low and a high lift -- the engine can misfire during cold idle because one or both intake valve lifters do not switch from high lift mode to low lift mode when the low lift feature is enabled.

    In some operating situations the low lift feature can be activated when the engine is up to temperature. For instance at idle. Low lift reduces engine friction and reduce pumping losses. If one or both of the #3 cylinder's intake lifters doesn't switch to low lift this can result in a misfire. The valve or valves stuck in high lift mode let in too much air and the cylinder runs lean and a misfire is the result.

    The only solution if the lifter or lifters are not switching to low lift mode properly is replacement. If it comes to this both intake lifters should be replaced.