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E90 stoich

Understanding AFR

Discussion and questions related to the course Understand AFR


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Is stoich of E90 9.8:1 or 9.0:1?

Actually it's neither. The stoich value for E100 is 9.0:1 and for E85 its' 9.8:1. For E90 you'd be at 9.5:1. in all honesty it makes no difference though and I never calculate the stoich value when I'm tuning on ethanol blends. Use the lambda scale and then lambda 1.00 is always stoich regardless of the fuel. Or do what most tuners do and leave the wideband set to the stoich value of pump gas (14.7:1) and ignore the fact that the actual number isn't technically correct. There's a lot more info around this in our 'Ethanol and Flex Fuel Tuning' course if you want to learn more.

Once the dyno tuning course is finished being paid off, that, boost control, and launch control will be my next ones purchased. At least until you get the LS on the engine dyno then I’ll be purchasing that course again. Thanks for the info Andre. One more question is, how do you go about setting the HP tuners to show lambda instead of AF? Is it a setting within the software?

Hi Damen, in the transform function you can choose to display in AFR or Lambda units.