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  1. #1
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    Misfires in 5th and 6th gear under load

    Hi all

    Recently an issue on my f30 335 has resurfaced in which I get misfires under load in 5th and 6th gear, which will result in turning off injection to one or more cylinders until I restart the car or clear codes in CANbus. Before, I solved this issue by swapping a plug in cyl 6 that was blown, but all my plugs look fine now. The issue persisted on both stock coils and PR coils, I'm back on stock coils right now.

    Currently running NGK 97506 @ .022". I'm considering dropping to .020 as recommended by bms to see if that helps. Meth PI kicks in at 11 psi and I've got fuel it's stage 3 lpfp. Running 1/3 tank of e85 (about 35%), but misfires occur with pump only and any mix of E.

    Any thoughts? Logs don't show anything unusual when this happens, but I can get a fresh one if it helps

    Thanks!

    This same question is posted on n54tech, forgive me for the redundancy

  2. #2
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  3. #3
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  4. #4
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    Auto or manual? I don’t know much about the N55, but, a worn dmfw will cause false misfires on those cylinders on high load/torque scenarios.

    also, do N55’s need a walnut blast like N54’s?

  5. #5
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    Its an auto, so no flywheel to worry about.

    IIRC the N55 doesn't build carbon as hard as the N54, but I run meth PI anyway so my ports should be squeaky clean

  6. #6
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    Could be the injector(s). Although rare, they can go bad.unfortunately the only way to test it is to replace them.

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