Phazer disassembly help...

[Surestick]

Are you sure it doesn't compensate for temp and altitude settings? I agree with the open loop statement, but imagine it uses intake air temp and barometric pressure to shift the fuel curves.

Agreed. It just won't compensate if the map is off like closed loop would for things like humidity, or ethanol in the fuel. At a guess it's probably programmed to be safely rich on E10 which would run a bit leaner than pure gasoline.