Recently I prepared the initial Flex Fuel settings in my ECU, and today I put E85 (from United) into the tank for the first time. After filling up, the ECU reported 45% ethanol concentration (reading from a Continental/Zeitronix/Haltech style sensor), which is what I expected because there was roughly half a tank of normal 98 fuel in there before filling up.
The car started up easily on the first attempt and drove like I hadn't changed a thing. That sort of 'transparency' is the whole point of Flex Fuel, but it was awesome to see it working perfectly without adjusting any fuel trims.
I'm sure it will be just as seamless with a higher ethanol concentration.
Now it's definitely ready for another power tune, I just have to organise a visit to MRC.

Can the ecu adjust boost based on the ethanol %? Or is it still a manual decision to change to boost controller setting by the driver etc?
 
For example:
0% - 30% - 24psi (your current boost level)
31% - 70% - 27psi
71% - 90% - 30psi

My ECU is the Adaptronic e1280s, which can do literally ANYTHING, or close enough to it. It's overkill for most cars, but I love it and I make good use of it's limitless configurability.
Most Adaptronic users have one of the 'Select' ECUs which are similar to other brands, but the e1280s is unlike any other ECU on the market. Many people have never heard of it though lol.

BTW, when I say my ECU can do anything...the tuning software has a user-configurable block diagram editor with many pages containing thousands of 'elements' which connect together to visually represent the entire functionality of the ECU. There is a default block diagram configuration which does almost everything, and it can be viewed in a simplified way that looks like normal ECU tuning software.
If I want to, I can add many of my own 2D tables, 3D tables, PID closed loop controllers, logic elements, adders, multipliers, timers, etc. and connect them to each other (or the ECU's inputs and outputs) in any way that I choose.

In other words, the algorithm that you mentioned is a walk in the park, if you know how to use the ECU!

Make sure that the small hose in your fuel tank is E85 compatible.
If not, you'll be changing it anyway pretty soon.

Admin
Make sure that the small hose in your fuel tank is E85 compatible.
If not, you'll be changing it anyway pretty soon.

If you're talking about the one that connects to the fuel pump, it is always supplied with Walbro pumps.

Sweet. As you know, taking the tank out sucks massively.

I thought the Walbro pumps sucked the tanks massively..

Dad joke!

 
Well, I am a dad - so I can!

Are you talking about the "banjo" fitting? If so, I don't believe it's replaced. Massive inconvenience & annoying restriction.