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How it works is the AEm or any UEGO reads a value of lambda which is 1 volt, anything lower is richer and higher is leaner. Lambda is the same voltage for all fuels, but in petrolium gas disply mode (lack of better term) the reading although not an accurate representation of what's going on correlates to teh proper AFR for ethanol to give you teh same "safe targets"
If you look at a chart with lambda and AFR for different fuel (included in the EM UEGO instructions) you will see that lambda (perfect burn) for ethanol is 9:1 and gas is 14.7:1 both have a value of 1 volt so even if you're seeing 14.7 the real AFR is 9:1 and since both are "stoichometric burns" for their respective fuels you can get away with reading the pump gas value of 14.7:1 and just calling it good.....Ethanol works like this all the way through the chart luckily... at a 11:1 gas burn, a rich wide open target afr has a lambda voltage of .747, you can cross the chart and see that ethanol will be at 6.73:1 which is where it needs to be for a rich WOT tune but the UEGO is still outputtinjg 11:1 because that's what you have it set to display. I hope this makes sense and these values are from the paper that comes with the AEM UEGO, so you can check yours to get a better idea of what i mean.
The simplest way to say it is you can use gaoline target AFR's on your wideband to tune ethanol because they represent the same values of ethanol needed for the same type of burn as the gas wants. When you read 11:1 you know that the ethanol is really 6.7:1 but it really doens't matter what value you use since both are the same in the mind of the uego
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