Question about OBC
 

I change my engine with 6 cylinder. Stock was M43B16 now it is M50B20 and the fuel consumption on the OBC is not accurate.
In the secret menu i put the fuel calibration on max...1250 i think, and even now it is not acurate at all.
What options I have now? It measures maybe about 5-6l/100km less then the real consumption :smile:

If you can find someone with a Compact 323i with an OBC, you could try "coding" your OBC in their car and then plugging it back into yours. BMW never sold a Compact with the M50B20, but at least that would bring your OBC's assumed engine closer to reality, perhaps close enough that you can trim the fuel calibration with the secret menu factor.

Can you find any menu items that will let you set the OBC's "EINHEIT" values? This would do the same thing, although again, you probably would have to find a 323i with an OBC to know what numbers to enter.

Another possibility would be to recondition the DME fuel injection time signal sent to the OBC. I expect the signal's pulse width and frequency are quite different than your OBC presently expects.