Fuel Trim
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2016 Ford Transit-350 HD, 2016 Ford Transit-350, 2016 Ford Transit-250, 2016 Ford Transit-150, and 2016 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.