[Sly_535i]

Hello all, I am dealing with a very frustrating misfire on my n55. It has a slightly rough idle on cold start for only about 1-2 minutes then it smoothed out. Once the engine is warm it only misfires under boost. If push the gas pedal more than 1/3 of the way it misses pretty hard and eventually throws codes for cylinder 5 misfire and fuel deactivation. I bought the car a few months ago and this is my first BMW so I’m not too familiar with the platform. As of right now the car is on a MHD stage 1 tune, catless DP, and upgraded charge pipe.

Recently it start misfiring so I threw in some new Bosch OEM plugs at stock gap. It still misfired. Then I tried replacing the coils with OEM Delphi coils, it still misfired. I sent a picture of the codes the DME threw for the misfire to a tuner and he said to try changing the injector because it could be stuck open. So I changed it with a Bosch EU5 injector and coded the flow rate in to the DME. It still misfires. I don’t know what I’m missing here but I would really appreciate some help. TIA

[paul223]

Is there voltage coming to that particular spark plug?

[Sly_535i]

Yes, it only misses during high load

[Sly_535i]

Now I’m getting cyl 1 and 2 misfire. Here’s a log if that helps https://datazap.me/u/sly535i/613-log...1&zoom=104-484

[00866b]

Check my thread I’m in the same boat as yours.

[ChiltiCoatl89]

Possibly Voltage related, check your Wire connections Also, how do your intake valves look?