Total Fuel Trim

Total Fuel Trim is a calculated value obtained by putting Short Term Fuel Trim and Long Term Fuel Trim together. The Total Fuel Trim value indicates how large a correction is necessary in order to keep the air/fuel mixture at the stoichiometrical 14.7:1 ratio. Total Fuel Trim values greater than 0.50 counts indicates that the PCM is adding fuel (increasing fuel injector pulse width). Total Fuel Trim values less than 0.50 counts indicates that the PCM is reducing fuel (decreasing fuel injector pulse width).