Fuel Trim
WARNING: This page does not describe the selected car, but rather 9 other vehicles, including the 2018 Ford Transit-350 HD, 2018 Ford Transit-350, 2018 Ford Transit-250, 2018 Ford Transit-150, and 2018 Ford F-550 Super Duty. However, it is still accessible from the selected car via links, so may be relevant.
The fuel control system uses fuel trim tables to compensate for the variability that occurs in fuel system components due to normal wear and aging. Fuel trim tables are based on fuel mass.