Commanded Lambda PID

[doc350]

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.

[Kevin@ProTuning]

I believe the only way to do that without switching tunes, would be with an ethanol content sensor and a factory pcm/calibration from a flex fuel equipped vehicle. If you're not referring to ethanol based fuels, I think it would be near impossible to implicate a feature like this based on fuel octane and/or oxygen content. A lot of stand alone EMS have this feature for ethanol content and blending that are user defined, however work pretty much like a factory flex fuel system.

[DSteck]

Use Commanded EQ Ratio. You'll find that it's actually commanded lambda.

[doc350]

Perfect. Thanks Dave.