[Shotimes] 10% Ethanaol and A/F ratio

[Paul Nimz]

I've always argued with Ron the fact that a 10% ethanol fuel will not  affect
performance due to the lower BTU content as long as the injectors and fuel
pump are up to the job.

What I have found on my '97 running an 89 octane/10% ethanol fuel is the WOT
fuel tables are way lean and the timing tables are way low with the SCT tune.
Both can be, or need to be increased about 10-15% to accommodate the fuel.
Ethanol also allows a hotter spark as it will increase the octane.

Around me only one station sells straight gas and that is 87 octane.  All
other brands/grades are 10% ethanol, 87, 89, 93 octane.  Casey's sells their
89 octane as the low end, as they should due to the state tax breaks on
ethanol, but their 87 octane straight gas is the mid priced fuel.  I feel the
10% alky mix must raise the octane by 2 pts to 89.  So I deduce all 90/10%
87oct mixes out there start out as 85 octane fuel.

So what I have to log or know now is if the Long Term Fuel Tables write into
the Base Fuel Tables.  If so the change can be logged and compensated for with
a few tweaks.

I've also read that a 15.6 or so A/F ratio is the best for fuel economy when
cursing.  This would require an off set to the O2 voltages when the PCM is in
closed loop somehow.  It appears that the SCT Advantage software is quite
limited compared to the Tweecer stuff, or so I read.  This is due to the
limited decompiling of the SHO OBDII code by SCT, or so I surmise.

Paul