Lets see if I can make what I'm looking for make sense.
With the scanner, I am reading my NGK AFX in Lambda. I have made a "Commanded Lambda" PID that is essentally Commanded AFR/Stoich AFR. It works well when I am using a fuel with a known Stoich AFR.
The issue that I ran into yesterday was when I was doing a Flex Fuel tune on a CTS-V. When the Stoich AFR changes based on the fuel composition that is currently in the car, it obviously skews my Commanded Lambda PID.
Is there a trick to making a PID that will take fuel composition into account?
I realize that sometimes it's easier to just do the math, but I've gotten spoiled with my histograms doing everything for me.