When you get your vehicle hooked up to a gas analser, you'll see the 4 or 5 kinds of emissions you're interested in, and a lambda or AFR value derived from those emission values. I was wondering how the AFR is derived from those emissions. Surely it takes more in account than just the oxygen concentration like a oxygen sensor; the AFR doesn't change dramatically when only the oxygen concentration rises.
Is it just a mathematical function with the emission values as its variables, or is it more complicated? Assume my CO is at 5%, my HC is at 150ppm, my CO2 is at 11%, and my O2 is at 2%. Can I calculate my AFR?