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Old 12-13-2015, 03:55 PM   #240
steve99
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Stoic ratio for petrol mixture is 14.7 parts air to 1 part fuel.
Stoic 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 charge. 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.

The ECU recalibrates the lamda value to read AFR for petrol that what you see in logs.

The fact that your running straight petrol or E85 does not matter to sensor and the ECU will try to still target stoic if you set the "afr" to 14.7.

The fuel trims will easily adjust for E10

All they really do in E85 tunes fueling wise is adjust the injector scaling so you don't run huge trims like 25%
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