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Thread: 2009 BMW 750i single cylinder misfire issue N63 leaving me baffled.

  1. #1
    Join Date
    May 2013
    Location
    Little rock, arkansas
    Posts
    2
    My Cars
    2007 335i & 2004 325Ci

    2009 BMW 750i single cylinder misfire issue N63 leaving me baffled.

    first off let me say by saying I have a lot of experience with BMW's and I am just helpless with what normally is a simple bad ignition coil.

    car: 2009 BMW 750i, well maintained with no smoke like they commonly do.

    trouble code 140801 cylinder 8 misfire

    Car starts up and idles perfectly smooth with no misfire all day long.

    As soon as you go to drive it and accelerate it starts misfiring on cylinder 8 and throws malfunction light and then the dme shuts the fuel off to cylinder8 to save the cat.

    shut the car off and start back up and misfire is gone and idles perfect. (until you accelerate)

    the only fault code I get is cylinder 8 misfire injection cut out. None else.

    I've replaced & tried:
    New spark plug OEM on cylinder 8 (driver side bank closest to driver)
    Used known good spark plug (gapped down as a test)
    5x different ignition coils including 2 new ones and moving them around from that cylinder to another one.
    2x series 12 fuel injectors.
    Performed compression test = 160lbs or more
    Replaced bank 2 HPFP with a known good one. (both banks read same fuel pressure)
    Reset all engine DME adaptations and did injector balancing procedure.

    Yet every time I go drive it I have misfire on #8 right when you get a little into the throttle and the turbos start to spool it cuts out.
    Again, at idle I can not get it to misfire once. Period. Even if I power brake it to simulate a load on it.

    What could possibly cause this or what would my next step be in the process of elimination?

    Thank you very much and I hope this thread will resolve it and help the next poor soul having this frustrating problem.

  2. #2
    Join Date
    Jul 2019
    Location
    California
    Posts
    5
    My Cars
    2019 Mazda CX5
    Quote Originally Posted by Wielandgeorg View Post
    first off let me say by saying I have a lot of experience with BMW's and I am just helpless with what normally is a simple bad ignition coil.

    car: 2009 BMW 750i, well maintained with no smoke like they commonly do.

    trouble code 140801 cylinder 8 misfire

    Car starts up and idles perfectly smooth with no misfire all day long.

    As soon as you go to drive it and accelerate it starts misfiring on cylinder 8 and throws malfunction light and then the dme shuts the fuel off to cylinder8 to save the cat.

    shut the car off and start back up and misfire is gone and idles perfect. (until you accelerate)

    the only fault code I get is cylinder 8 misfire injection cut out. None else.

    I've replaced & tried:
    New spark plug OEM on cylinder 8 (driver side bank closest to driver)
    Used known good spark plug (gapped down as a test)
    5x different ignition coils including 2 new ones and moving them around from that cylinder to another one.
    2x series 12 fuel injectors.
    Performed compression test = 160lbs or more
    Replaced bank 2 HPFP with a known good one. (both banks read same fuel pressure)
    Reset all engine DME adaptations and did injector balancing procedure.

    Yet every time I go drive it I have misfire on #8 right when you get a little into the throttle and the turbos start to spool it cuts out.
    Again, at idle I can not get it to misfire once. Period. Even if I power brake it to simulate a load on it.

    What could possibly cause this or what would my next step be in the process of elimination?

    Thank you very much and I hope this thread will resolve it and help the next poor soul having this frustrating problem. Visit autoguysland to view how long we can drive with a misfiring cyclinder.
    There are some posts related to your issue. You can refer it to see if you can solve your problem or not. Hope it can help.
    https://www.bimmerfest.com/forums/sh....php?t=1166241
    https://www.bimmerfest.com/forums/sh...d.php?t=605881

  3. #3
    Join Date
    Mar 2020
    Location
    Encinitas
    Posts
    1
    My Cars
    Bmw

    Misfire

    Quote Originally Posted by Wielandgeorg View Post
    first off let me say by saying I have a lot of experience with BMW's and I am just helpless with what normally is a simple bad ignition coil.

    car: 2009 BMW 750i, well maintained with no smoke like they commonly do.

    trouble code 140801 cylinder 8 misfire

    Car starts up and idles perfectly smooth with no misfire all day long.

    As soon as you go to drive it and accelerate it starts misfiring on cylinder 8 and throws malfunction light and then the dme shuts the fuel off to cylinder8 to save the cat.

    shut the car off and start back up and misfire is gone and idles perfect. (until you accelerate)

    the only fault code I get is cylinder 8 misfire injection cut out. None else.

    I've replaced & tried:
    New spark plug OEM on cylinder 8 (driver side bank closest to driver)
    Used known good spark plug (gapped down as a test)
    5x different ignition coils including 2 new ones and moving them around from that cylinder to another one.
    2x series 12 fuel injectors.
    Performed compression test = 160lbs or more
    Replaced bank 2 HPFP with a known good one. (both banks read same fuel pressure)
    Reset all engine DME adaptations and did injector balancing procedure.

    Yet every time I go drive it I have misfire on #8 right when you get a little into the throttle and the turbos start to spool it cuts out.
    Again, at idle I can not get it to misfire once. Period. Even if I power brake it to simulate a load on it.

    What could possibly cause this or what would my next step be in the process of elimination?

    Thank you very much and I hope this thread will resolve it and help the next poor soul having this frustrating problem.
    I have 2011 550i sport package with same problem did you ever fix your car if so what was the problem?

  4. #4
    Join Date
    Sep 2006
    Location
    Windy City, USA
    Posts
    2,768
    My Cars
    2010 750li & 2008 X5 4.8
    I had this same problem on my 2010. Had new spark plugs out in several times and misfire went away. Funny thing I use the same brand spark plugs each time.
    Last edited by roys740; 04-10-2020 at 09:10 AM.
    Current: 2010 750 LI Sport (Ruby Black) and 2008 X5 4.8L Sports Package (Metallic Black)
    Previous: 2001 740 IL M-Sport package (Schwarz Black),
    2001 X5 (Metallic Black) &
    1998 740 IL (Artic Silver).

  5. #5
    Join Date
    Jun 2020
    Location
    California
    Posts
    46
    My Cars
    2015 x5
    your compression test should be more than 160psi. I would borescope the cylinders and check if the top of the pistons. if its clean on the edges, your rings are done. I would also check the cyl walls for scoring. These engine are shit esp at 100k miles. Majority of problems start 50k+ miles

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