O2 sensors are lambda sensors and that’s what they report. They don’t give a shit if you are burning piss or whale jizz as fuel. Stoich is always going to be 14.7 if your wideband controller isn’t adjusted to report the actual mixture for X fuel @ X lambda value. Typically, unless I’ve scaled the stoich value in the tune for the new fuel – I just leave the good old gasoline scaling on my wideband and run it.