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Is oxygen concentration % the same as AFR?
They are related, but not the same thing.
The oxygen remaining in the exhaust gases is measured by the lambda sensor, which gives a voltage and that's used to give an AFR or lambda value.
A lambda value of 1.0 is stoichometric (sp?), which in theory is the ideal balance for the fuel and oxygen to be fully used, with a higher values being leaner, and a lower value being richer.
This is where it gets a bit tricky, as for the same lambda value, different fuels will have different AFRs, as their chemical mixtures are different. This is especially confusing with, say, an alcohol blend having a true AFR of 8.0:1 with a lambda of 1.0, but a standard meter that hasn't been calibrated for the fuel will still read 14.7:1, which is the AFR for petrol/gasoline. For this reason, working with different fuels, it's good practice to stick to lambda values rather than AFRs.
This may be useful to get the idea.
On my data logging i get oxygen concentration in % is there a way to use this to determine AFR or Lambda?
Strange, that's not a very useful metric for vehicle tuning - it is specifically for vehicles, rather than a generic atmospheric gas analyser?
In the meantime, https://wbo2.com/sw/percent-o2.htm and https://www.researchgate.net/post/How-to-calculate-oxygen-percentage-from-lambda-value - the second is less technical, but you will need to re-write the equation.
