The PowerFC only supports manual cars (excluding Toyota). It will work on an automatic car however it will not handle gear changes and simply keep the throttle nailed during a gear change. This will result in jerky gear changes and stress placed on the gearbox. The factory ECU during a gear change will communicate with the auto box and drop timing, ignition to ensure a smooth change. For those wishing to use PowerFC with auto you should consider a mechanical auto gearbox instead of an electronic. The PowerFC should work fine with a mechanical gearbox such as power glide, transbreak etc.
This is because the mainstream ECU's in Nissan etc rely on the main cars' ECU for gear logic change control and functions. Cars such as the Toyota have a seperate ECU for the gearbox change logic and control so it's not affected. Apexi chose not to port the Automatic gearbox logic code (as its very long and complex) into the PowerFC because I suspect they found its simply not worth it & too complicated. You can buy an Automatic PowerFC for a Toyota Chaser for example and it has auto logic control under SETTING, you can set the shiftmap, ramp up speeds etc as it has the code to interact with the Toyota AUTO ECU that is seperate to the main ecu. So in summary - Auto PowerFC's exist & work but only for Toyota. We have seen quiet a few Auto R33 Skylines with manual PowerFCs - some report they work fine etc and there is no difference - do so at your own risk.