I live in Colorado, just outside of Denver.
We have 3% less oxygen here (compared to sea level 18% versus 21%) and almost all our gas is E10 (probably 5-10%)
I beleieve the stoich for E10 is 14.08 (asuming it is actually 10% ethanol.)
The air density in Denver (5280 ft) is about 82% of that at sea level (0.0627 vs. 0.0764 lb/cubic ft at 70 deg F)
How does 3% less oxygen affect a 14.7 and 14.08 stoich?