Originally Posted by SeeeeeYa
So that causes some problems then. Gear changes would have to be interpreted quickly (especially for drag racers), and changes made accordingly. You'd have to give some thought to the gear transition (which wouldn't be as easy as having step-function changes). Things like FFS and LC would interfere.
You also can't compensate for clutch slip. Ideally, you'd know that clutch slip occurs and would drive responsibly. But the ECU wouldn't know that you are launching, or slipping the clutch intentionally in the dirt or snow. You'd have to account for that, and there's some different ways to do that (i.e. default to wastegate or low boost when gear position is undefined).
But you could also use that to your advantage, by retarding timing when road speed is greater than zero, and there is no matching ratio (i.e. during shifting). That, along with target wastegate boost, you could effectively build FFS into the ECU without having to rely on either clutch switch.
With a standalone, you could build a controller so the ECU would be able to predict the next gear change based on current gear and the lower clutch position switch (i.e. clutch starts coming out, feedback RPM:speed to determine if the next gear is above or below the current gear, and select that boost and timing map).