Tuning for NOT Gasoline

[XfireZ51]

Some time ago I believe Halverson brought up the subject of tuning for E85 and the LT-5. That's been something done for the LS-7 so understandable Hib would bring it up here. Of course, newer Powertrain management systems are automatically adapting to various fuels thru flex fuel systems. For many of us
E10 is the primary fuel available so I thought I'd would just reiterate a point when dealing w any fuel other than straight gas.

Forget AFR for a moment and think in terms of Lambda. Lambda is "agnostic" to the type of fuel being used. A Lambda of 1 is always stoich for that fuel. If you are burning E10, a Lambda of 1 occurs at an AFR of less than 14.7 for a WB calibrated to E0. By telling the ECM you are shooting for an AFR of 14.3, the ECM uses that as part of its PW calc, automatically making the mixture richer in respect to a 14.7 stoich, but correct for a 14.3 stoich.
Now I understand that when I see a Lambda of 1 on my ZT-2, it's saying that I am at 14.3(the AFR commanded in my cal) although my AFR gauge reads 14.7.

That's why just setting the Stoich AFR does the trick because the NBO2 switching point will be for whatever fuel basically. And since AFR adjusts the PW, more fuel will be added(if lowering the AFR) correspondingly to hit 128 if you are tuning for C/L. Tuning for E85 then would follow in the same way. So for WOT tuning, unless your WB can be re calibrated for the fuel being used, the indicated AFR would need to be corrected. As an example, if I tune WOT to an indicated 13:1AFR
straight gas, I should really be down around an indicated 12.6:1 for E10 IF I am using UNCORRECTED AFR to tune. 13/14.7= .884, then 14.3*.884= 12.6 indicated.

This is where a bin switcher becomes helpful for us. You could have multiple cals loaded using various AFR constants depending on the fuel being used. You would do that manually. Incorporating a flex fuel sensor would be cool to then automatically invoke the appropriate calibration.