Quote:
Originally Posted by Ilma
Thinking something like this then:
The best ratio for gas mixture is 14.7 parts air to 1 part fuel.
The best ratio for e85 mixture is 9.8 parts air to 1 part fuel.
The O2 sensor does not know how much air or fuel you started with. It only knows oxygen levels left in the spent exhaust.
The O2 sensor reports in terms of lambda. If the lambda value is 1.0, the fuel is burned optimally, and started with the right mix. Whether you start with gas at 14.7:1 or e85 at 9.8:1, the lambda will be the same at the O2 sensor.
So are the datalogs reporting the gasoline equivalent AFR while using E85. 
Since gasoline stoich is 14:1 this means that the O2 sensor is returning a lambda of 1 (all oxygen burned) but you are probably really running a richer AFR for E85 than what is showing.
In the end, a lambda of 1 would simply mean you are burning the all the oxygen that is required by the E85 blend in the tank.......but the more ethanol you run, I would guess that lambda gets closer to the 9:1 stoich that ethanol needs in order to burn all the oxygen molecules in the AFR. |
Correct.
Lambda is what matters. It is just interpreted as "respective gas AFR" in the logs for consistency and convenience if you think positively
The "true AFR" doesn't really matter.
Closed loop reads lambdas and adjust them automatically so that we don't need to bother about different AFRs of different fuels.