I'm still trying to figure out exactly what E10 looks like on a O2 Sensor, I have a wide band sensor I use with my carb.

From what I understand, an O2 sensor doesn't actually measure air fuel ratio directly but computes it from oxygen in the exhaust.

This measurement is called Lamda. A Lambda of 1 gives you a stoichiometric AFR no matter what the fuel mix

So if you add ethanol the indicated AFR is incorrect, but an AFR of 14.7 ( a Lambda of 1 ) is still stoichiometric.


I think that anyone tuning anything these days has no excuse to not be running a WB O2, theyre cheap and accurate.


The other question is where on the AFR curve should we be running.

I'm betting about stoichiometric or slightly richer. But no one seems to be publishing that info