Hello Scotty! Big fan of yours. I have a question: I drive 2004 bmw 325i and I did some obd test, my long term fuel trims in both banks are negative, what does it mean? Car seems to run fine and no trouble codes.
i will really appreciate if you can help me to understand it better. I will attach obd report.
Thank you very much, I know you are a busy man!
Mike Petrov
Could be a few things but if you want to find the root cause test the fuel pressure and check the injectors.
@jacksonishere
Thank you, will do. Seems like mighty be O2 sensors. Car has 114k miles and I don’t think they were changed.
And look forward to the report... can you do waveforms? Is stft oscillating or max neg? We'll await your report.
edit, oh and whats the downstream O2's at?
@hillbilly
Both banks negative 7%. Seems like mighty be O2 sensors. Car has 114k miles and I don’t think they were changed.
I agree and where to start. Oil usage over the years? While you have those O2's out get a gage and check pressure diff across cat as can give you a good indicator of it's condition (could be part of the issue to). GL and keep us informed : )