I know I don't post much... nearly not at all. I usually just use the gaslog. I have to chime in, though. I have a thought.
I've downloaded the Torque Pro app for my Android phone. I like the program, and it shows up as the 1st OBD2 Scanner app on Google Play. I've noted a problem with it, though. When it gives MPG, it uses some algorithm that accounts for speed, vehicle weight, engine size, yadda, yadda, yadda. I KNOW the app will read and display both speed and fuel flow. Why the developer didn't write the MPG algorithm to simply divide speed by fuel flow is beyond me.
So... does anyone know of an app that does this, or should I set about developing one of my own?
Its because the OBDII computer does not know fuel flow. Any mileage device, like a Scangauge, Ultragauge, Android app... etc., has to estimate fuel flow. That's why you have to input all those parameters.
Its something people like us like to know, but the computer does not know fuel flow. It knows airflow, RPM, displacement, fuel trim, throttle position, and injector duty cycle. Using these parameters you can get a really good estimate of fuel flow, but its just that. An estimate. Even if you put a fuel flow sensor in the fuel line, you won't get an accurate reading of what's actually going into the engine, as once fuel enters the fuel rail, the injectors take only what they need. The fuel pump runs constantly at the same rate, and what isn't used goes back to the tank.