The ECU’s in the F3 and F4 are basically the same, with the same approach to control. The info I have pertains to the F4 but is transferable by principle to the F3.
There are numerous maps in the ECU, changing the selection of Normal, Sport, Rain or the custom settings do not change the base maps i.e. ignition, fuel etc. What they do appear to change is the data provided to the tables. e.g. the hand throttle position is translated in to an accelerator position (at the throttle bodies). The throttle at your hand is relative position, as it can be mapped to different actual throttle body positions. see attached pic.
Parameters that are changed based on the selection of Normal Sport or Rain or the custom settings
• Engine Braking, maps for Normal and Sport
• Max RPM, maps for Normal, Sport & Rain
• Throttle position, maps for Normal, Sport & Rain
• Max Torque, maps for combined map for Normal & Sport, separate for Rain