I converted my 2006 Silverado to Flex Fuel. Wired in the sensor and turned everything on in the tune. It is reading 75-80% alcohol on the scanner and Commanded Stoich is changing. It is not adding the spark from the Flex Fuel adder table though, this is the main reason I wanted to have it recognize e85, I am boosted and want to take full advantage of the added timing but run either fuel and not worry about reflashing. So it dawned on me one night that there is no where in the tune to select a point to start using the flex settings, if I only have 40% ethanol I would want less of the timing in the adder table then when there is 80%. I hope I am making sense here, Can someone point me in a direction? Anyone else noticed this or have a fix? This is for anyone who has converted a P59 non-flex OS to flex. I suspect that original flex fuel OS's work correctly. I will post the current tune but no logs the motor is out of the truck right now, have not driven it in a few months but the new motor and turbo set up are just about finished and would like to get back on this.