Flex Fuel Master enable/Disable Tab?

[02Ls1]

Guys I have a 2010 5.3 boosted silverado been tuned for several years, I had a problem with the PE when I first start tuning it. Truck would't go in PE at WOT so I search around and found that I had to disable the FlexFluel tab, I disable it and it work truck goes in PE at WOT.
Now since I sold my race car I would like to race this truck, I'm planing on going e85 since a new gas station close to me is selling e85.

My truck is e85 compatible do I need to enable the Flex Fuel tab? Never found why on enable would't go in PE mode using 93 octane.

[02Ls1]

Have anyone had this problem?

[schpenxel]

Does it have a flex fuel sensor or is it using a "virtual" sensor? There should be a setting in the original tune that says sensor type

[02Ls1]

I'm not near my laptop, tomorrow I will check and let you know.

[02Ls1]

It's says virtual, Fuel Sensor Virtual

[schpenxel]

Virtual looks for a certain increase in fuel tank level (not sure, but it's 2-3 gallons I believe) and then tries to figure out the new ethanol content (without a sensor). I assume it sees the change in fuel trims and adjusts the ethanol content/stoich AFR accordingly to cancel them out, but I've never played with it in person.

[02Ls1]

So if I change it to sensor it won't do nothing do to my file has the virtual?

I pump e85 today and I just enable back the flex fuel tab dialed in the truck and made a few WOT runs. It run pretty good air fuel read 10:8 at WOT, I just read the e85 as gasoline.

[schpenxel]

If you set it to use the sensor and there isn't a sensor I believe there is a setting in there for what alcohol content to use if the sensor has an error (which I suspect you'd have..). You can try just setting that to whatever ethanol content you want and seeing how it does.

I've never done it so I can't say for 100% sure that it will work like it should but it's worth a shot. You can always log ethanol % and see what it's using

[Redline MS]

Virtual looks for a certain increase in fuel tank level (not sure, but it's 2-3 gallons I believe) and then tries to figure out the new ethanol content (without a sensor). I assume it sees the change in fuel trims and adjusts the ethanol content/stoich AFR accordingly to cancel them out, but I've never played with it in person.

Actually after the controller sees a tank level change it actually adds spark timing to see if it has knock. If it doesn't see knock it deems it to have higher octane fuel and switches to ethanol control. Then it trims from fuel readings