Stoich AFR at 1mile high

[smcstevesmc]

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?

[cobaltssoverbooster]

not much. im in reno at 4250ft and i go to tahoe at 6224ft. i use the same settings from 0 to 6K. i am tuned to remove fuel for higher elevation so if i go to 0ft then my trims start adding back by going positive. It's not too big of a deal. If your concerned, tune in Lambda instead of AFR. Lambda 1 is always stoich no matter what the fuel is.

[smokeshow]

It is not JUST the oxygen that is absent at altitude....its everything else in the air as well. So stoich does not change...