customh

I googled and searched the forum for something on this topic but came up dry. Everything I saw was about trying to avoid ethanol.

I'm wondering if there's anyone out there experimenting with blends to see what I should expect. I've had 87 E10 in mine from day 1, and now I'm reading that E30 is the best blend for mileage. I intend to test this when I am around stations that I can find the fuel at.

violinguy77

If anything you will see a decrease in mileage as the ethanol content increases. By volume ethanol has less energy than straight gasoline so it takes more fuel to go the same distance.

papa tiger

E85 turns up the available torque some 10/15 lb.ft. Takes slightly more fuel volume to get there. It samples the ratio of gas an ethanol to give its best whatever the %.

buck91

You sure about that? I always figured it just used the knock sensor/octant adaption algorithms in combination with E85 compatible hoses/seals/etc.

RLXXI

papa tiger is correct, one of the many things the pcm does to accommodate the ethanol is to increase injector pulse width (on time) this in turn delivers more fuel for the same intake sequence.

Lots of other factors but the IPW is the main one that creates less fuel economy.

.

buck91

Interesting.

packplantpath

You sure about that. Papa claims there is an octane\ethanol sensor. I haven't seen one of those in a few years. The outcome may be the same, but I'm pretty sure there is no actual fuel sampling going on. Octane/ethanol content is inferred from knock sensors and widebands not directly sampled and tested.

I know some older flex fuel vehicles had an active sensor which only tested fuel octane and ethanol. But I don't think newer f150s do.

papa tiger

It uses alternating pulse width modulation to sample and the higher the value the more ethanol in the gas. The higher the ethanol % the higher the anti knock qualities in general. The whole thing isn't that simple but a basic diagram. ECU connects the whole system with the PCM management of fuel injection / transmission shifts.


I like E85 in one of my Flex fuels when the outside air temps rise near 100 for sure as I can feel its torque rise where torque usually decreases due to the heat on the hills with 1 specific hill in mind where the outside air temps always rise by nature on it 2 or 3 more degrees. 103 and above seems to be a real area where the E85 jumps up there and helps. The truck doesn't have an operational problem no mater the concentration of E85 to gas.