Does GM tune these DI engines to run rich? Should I change the AFR to something leaner at 10% Ethanol and below? like 14.7:1
Looking at annother factory tune I have for a 2015 5.3 0% ethanol is set to 14.7
Always open to learn. Thanks for the help in advance.
The factory 5.3 is a flex fuel truck so 0% would be 14.7 roughly..
GM and other automakers account for 10% roughly ethanol hence the stoich or 14.1
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oxygen sensors switch around the stoich of the fuel in the tank, not the value in the tune.Originally Posted by HellKnightHicks
this means that if you are running E10 your O2 sensors will switch around stoich for E10.
if you run E0 your O2 sensors will switch around stoich for E0.
stoich for E10 is 14.1
stoich for E0 is 14.7
if you run E10 but program the calibration for stoich of 14.7 it will still run at stoich of 14.1 by using Fuel Trims to compensate for the error.
that logic applies to all other potential combinations of calibration stoich value vs what fuel is in the tank.
GM uses 14.1 as stoich because almost all pumps now supply E10. That's all there is to it.
You cannot run leaner or richer in closed loop with fuel trims and oxygen sensors. It just runs at stoich, unless the engine is cold or you floor it (or some other atypical situation).
Awesome thanks for the info and the fast response.
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