Hi,
I have bought a F10 M5 8 months ago and since then i am suffering from the smell of raw gasoline (like rich mixture).
I have an MHD obd2/wifi dongle and have done a lot of datalogs where AFRs seem very good - solid 14.7 on idle and low load, however if you judge by the smell it is more like 12
I know that smell is expected with catless downpipes, however it doesnt feel right at all to me. I used to have an E30 with M20 straight-six with no cat and have spent countless hours tuning its standalone ECU watching out the AFR and have never experienced such strong smell.
My clothes when i go back home literally smell like soaked gasoline which is quite frustrating.
Since i got the car i replaced all injectors and coils (just to be on the safe side - 110k km) and it seems this improved the situation with the smell a little bit, but not enough. Unfortunately the people who replaced the injectors did not reset fuel adaptations and i have done around 1000km since then and LTFT still are much higher than i would like them to be (10+ on WOT on one of the banks) I was suspecting bad injector(s) causing the closed-loop lambda control to go crazy trying to achieve average target AFR for 4 cylinders, so LTFTP fuel adaptations must be reset on injector change i believe! I have only the MHD monitor license, so can not reset them myself (it requires the flasher license)
I am wondering if my mixture is really too rich, even though log says its fine (14.7) on both banks and how to verify that.
Anyone has an idea if O2 sensor goes bad could it still seem fine, but just read leaner than actual?
Or some sort of exhaust leak which could lead to skewed O2 sensor AFR readings..?
I have asked several people around me with S63 engine and catless and all of them claim they sense no gas smell whatsoever, which also confirms my feeling that something is wrong with my car.
I plan to revert the ECU tune to stock just to confirm its not the tune.
I could also replace the O2 sensors, but looking at the logs they do not seem faulty at all - very smooth and very responsive graphs, very similar on both banks.
Car has been thoroughly checked for vacuum and exhaust leaks and mechanic claims its perfect. I also have the typical Wastegate rattle (which I suspect might also be the SSP Spec-R clutch - not sure..)
Otherwise the M5 runs very very strong, almost scary strong, especially considering the grip situation
Any ideas and suggestions are welcome and appreciated!