What is Short/Long Fuel Trim? Fuel Trim refers to feedback adjustments to the base fuel schedule. Short Term Fuel Trim refers to dynamic or instantaneous adjustments (i.e., during braking/accelerating). Long Term Fuel Trim refers to much more gradual adjustments to the fuel calibration schedule than short-term trim adjustments. Long term adjustments compensate for vehicle differences and gradual changes that occur over time. Special Thank http://www.scantool.net/