my car is 2013 bmw f10 528i ( 4 cylinders GDI turbo charger engine).
At some point, my tailpipe started to have a soot.
So I watched AFR carefully with OBD tool.
When cruising ( 80km/h , rpm is 1500 approx?) , AFR refers to 14.6-14.7, and at some point, it varies greatly from 13.2-14.3.
So I cleaned the MAF and cleaned the MAP sensor ( use MAF sensor cleaner).
Still, AFR was not normal, so all O2 sensors bank1 bank2 were replaced.
The ignition plug and ignition coil have also been replaced, and there is no engine malfunction(Idle rpm is stable.)
The only thing that bothers me is that the tailpipe gets dirty with the soot, the AFR fluctuates a lot, and I don't know if it's just my feeling, but I think the gasoline consumption has increased.
Please tell me your solution.
* i have already been replaced : spark plugs, ignition coils. MAF sensor, O2 sensor Bank1, bank2. high pressure fuel pump ( GDI fuel pump) , turbocharger assy( cause oil leak to exhaust impeller) .
* i have not checked: catalytic converter in and outside inspection( melt or break.)
cylinder compression. low fuel pressure , high fuel pressure .
plz help!
i always use premium gasoline.
You have a direct injection turbo engine, odds are that the valves are carbon built up. You need to clean them.
Is carbon buildup related to tailpipe soot? At 25000 miles, I removed the intake carbon. ( no walnut. use crc gdi intake cleaner) Then I installed an oil catch can. It is currently 60000 miles. so i already installed oil catch can. i will re-check intake valve carbon buildup.
If the valves do not operate correctly, you will might end up with the soot. Check the valves by a borescope. Also, make sure you empty the oil catch can regularly.
Well, common for many car brands (such as BMW, etc.) that do have oil consumption that can contribute to soot buildup in the tailpipes....
ummm.. My engine has no oil consumption yet. I change the oil every 5000km.
Well....you can't assume that your BMW doesn't consume oil...did you measure of how much oil ya drained??? Probably not. I wouldn't be surprised to see the amount of drained oil falls below the amount of oil you need to pour in that engine..