E85 calibration for emissions testing

[XfireZ51]

Originally Posted by Marc Haibeck

Jep,

As I understand it, the OE switching oxygen sensors switch at a ratio of oxygen in the exhaust verses the 20.8% in the air. That represents stoichiometric combustion of gasoline. The ratio is very different for stoichiometric combustion of ethanol, so a switching sensor calibrated for gasoline would not work correctly with ethanol.

Marc,

Yes you are correct. I think E85 stoic is around 9:1 while stock NB O2 is calibrated for gasoline with a switching point optimized for 14.7:1. It is possible to adjust the O2 switch point but I suspect not to the extent needed to accommodate E85. Same for the WB. As I presented at the last Gathering, I play w these values to account for the E10 w a stoic of 14.3:1 and for dealing w the increased overlap of bigger cams. I might read up on how this is being done on the C6. I imagine O2 sensors from flex fuel vehicles may be alternatives.