The ecu in any car is designed to control how the engine operates. Car manufacturers want their engines to produce power, while still being fuel efficient, reliable, quiet, etc. The way they accomplish this is by defining "maps" which contain modifiable parameters that the ecu will use to make decisions on how the engine should be working. In the case of the Simos18, there are both measured values and modeled values in these maps.
=== In short: ==Primary Strategy =
The accelerator pedal tells the ecu how much torque the driver wants the engine to produce.
That driver input is referenced against a table that defines the maximum torque available at any given RPM.
That target torque value is referenced against other maps which define how much airflow, followed fuel and timing, the ecu should target to achieve the driver request torque value.
= Simos Tuning =
The Simos ECU flash files contain a number of blocks:
#CBOOT
#Application Software 1
#Application Software 2
#Application Software 3
#Calibration Block
When the ECU is recalibrated, there's portions of each block overwritten. The calibration block is what's loaded during map updates (which is why the first flash takes longer than the rest).