Single turbo N54 Misfires

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Dec 9, 2018
Hey guys!

Just finished my single turbo build and are now trying to make some logs for tuning.
But I am experiencing som misfire issues on high rpm and high load.

Car is a 07 335i N54 MSD80. Running MHD with a custom tune and BoostBox.

I am usually getting these codes:
29CC - DME: Combustion misfires, several cylinders.
29CD - DME: Combustion misfires, cylinder 1.
29CE - DME: Combustion misfires, cylinder 2.
29CF - DME: Combustion misfires, cylinder 3.

Plugs are NGK 97506 and Bosch coils. Both are new. Regapped plugs to 0.02". Also tried swapping both plugs and coils around.
Still getting these kind of codes on cylinder 1-3. Not always all of them. Sometime just one or two cylinders.

I have just rebuilt the engine and plugged off vac ports, so these are clean. Injectors are brand new oem index 12.

Can this be a Mosfet issue?

Thank you for any input!


Dec 9, 2018
Thank you! I will check the dme and take contact if there is a problem with it.

Here is a log. I got misfires at 6500 rpm, hence not reving longer.



Dec 9, 2018
Thanks for input guys. I will hear with my tuner. Hopefully it is just the tune causing this.

What would you recommend if I need new 02 sensors? I have a Speedtech kit. How are those NTK sensors?

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