MPG Testing AR-5 + 93 Octane

[Marlin]

I will say that the ethanol content makes a huge difference pending the vehicle and loading. WHen I towed the VX out to Moab behind my expedition, I went from 9-10mpg with ethanol to 12-14 once I hit WY I think, maybe KS. That included all the mountains and everything. Our trucks were never designed with ethanol in mind, so it may make a difference.

[89Vette]

Our trucks were never designed with ethanol in mind, so it may make a difference.

From everything I learned about computer operation and tuning, ethanol is usable in any ODB2 vehicle (including VX). The injectors and fuel lines haven't been reported as degrading due to ethanol content either.

Though I originally had thought the difference was closer to 10%, materials I've read more recently suggest 5% increase in fuel usage should be expected when running E10 vs gasoline. Even IF closer to 10%, pure gasoline cost THAT much more too -- so there's no gain even if you can find/pay for it. Though it's nice to post numbers, it still hits the pocketbook about the same.

Finally, the O2 sensor is the primary component that IS designed to compensate for differences in fuels. It's "delta" changes with the change in fuel. It sees the need for more fuel and asks the ECM to provide it. Injector pulsewidth (PW) increases with the need for more fuel to get the burn back to a delta of "1". Where some talk about changing AFR from 14.7 to 14.1 that's just a starting point for most ECMs. Ultimately, the ECM is constantly monitoring for any changes in fuel -- whether crappy or E5, E10, or E15. It "knows" how to react by monitoring the O2 sensor.

Because there are limits, it takes a special system to handle something more extreme like E85. ECMs can only compensate so much. In the case of 1st generation ODB1 computers, the tolerance was +/-15%, giving a total "spread" of about 30%. OBD2 computers might be even wider.

I think I heard where they finally are realizing making fuel from corn is/was a bad idea. Seems I heard at least one state was considering LOWERING ethanol content. But, I didn't hear that first hand.