Unless the vehicle is designed for E85, then it will run lean and eventually trigger a check engine code. Flex fuel vehicles use an ethanol content sensor or sometimes infer the ethanol content from the o2 & knock sensors in order to adjust for the E85.My question is, what happens if you put E85 in with OEM everything?
Very broadly, your O2 sensors will see a lean condition, the fuel trims will add a whole bunch of fuel to get to E85's much richer Stoichiometric ratio, and you'll get much worse fuel economy. Very likely the fuel trims aren't broad enough to add enough fuel, so a CEL will happen saying something like "too lean", and the car may continue to run like crap. If you push the engine too hard before the fuel trims have sorted out, you run the risk of putting lean-burn holes in your pistons, or general ka-blamo. Just sayin'.In the owner's manual it says we can put E5 & E10 in our cars with no problem. My question is, what happens if you put E85 in with OEM everything?