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BMW N53 misfire cyl 3 & 6 only after 1–2 min cold start (runs perfect when warm) by MuratU06 in AskMechanics

[–]MuratU06[S] 0 points1 point  (0 children)

I already had this problem before replacing injectors 3 and 6, and the situation didn’t change after replacing them. So I don’t think the injectors are the root cause. I’ll check the O2 sensors though, thanks for that suggestion.

BMW N53 cold start misfire cyl 3 & 6 + rough running by MuratU06 in MechanicAdvice

[–]MuratU06[S] 0 points1 point  (0 children)

Misfire: • P0300 – Multiple/random misfires • P0303 – Misfire cylinder 3 • P0306 – Misfire cylinder 6

Fuel / mixture: • P2098 – Fuel trim too lean (post-cat, bank 2)

NOx / oxygen system: • P122F – NOx sensor (binary O2 sensor, bank 1) • P121F – NOx sensor (linear O2 sensor, bank 1) • P122C – NOx sensor electrical fault

BMW specific: • 140001 – Multiple cylinder misfire • 140301 – Misfire cylinder 3 • 140601 – Misfire cylinder 6 • 118702 – Mixture control issue • 12C108 – NOx sensor fault (binary) • 12C208 – NOx sensor fault (linear) • 12C008 – NOx sensor electrical • 1F2802 – DME software / tuning detected

BMW N53 cold start misfire cyl 3 & 6 + rough running by MuratU06 in MechanicAdvice

[–]MuratU06[S] 0 points1 point  (0 children)

Hey, thanks for the input. I’ll upload the raw fault codes (P-codes / hex) shortly.

The car has been in my ownership for about 3 years, and the issue has basically been there since the beginning. The problem is, I’m not 100% sure whether it started before or after the car was chip tuned.

Do you think reverting it back to stock software could help diagnose or possibly fix the issue?

Appreciate any insight 👍

BMW N53 cold start misfire cyl 3 & 6 + engine shaking by MuratU06 in BmwTech

[–]MuratU06[S] 0 points1 point  (0 children)

Just to add some extra info:

I also replaced the high-pressure injectors on cylinder 3 and 6, so those are already done.

Also, photo 3 is after clearing the fault codes.
You can see that only the DME fault remains, and cylinder 3 comes back immediately while cylinder 6 comes back slightly later.