Hi guys,
Last winter I had an issue with BMW 328i(N20) and this lean code, replaced low pressure fuel pump in the tank, and after that code didn’t came back for almost a year.
Now with cold weather I got it again.
My LTFT on cold start and idle are around 24%, while driving 25-27%.
After the engine (N20) and oil reaches operating temperature LTFT are around 17% at idle and jumping to 25% with little bit of throttle. But also second scenario that is happening right now is that LTFT are at 29% at idle and going down to 24% with blimp of a throttle. Thing that is confusing me why is sometimes LTFT at idle 13% and sometimes at 29%?
STFT are normal and fluctuating from -5% to 5%.
This is the same behavior that I had last year. I checked roughly 20 times intake pipes for cracks, cleaned both MAP and MAF sensors, replaced fuel pump and its still occurring now in cold weather.
I am really hoping that is not injectors, if you have any suggestions that would be appreciated.
First: engine stock or “tuned”? I am assuming a stock engine as some ECU tunes will cause exactly those massively positive long term fuel trims under certain conditons.
If you have INPA you may t-r-y to reset adaptive parameters for the fuel delivery system. Sometimes it works and sometimes it doesn’t, generally worth trying.
If resetting adaptive parameters doesn’t work, next stop are the fuel injectors. Before replacing them I would send them to be bench-tested: it’s likely a couple are worn out.