Long Term FT

The Long Term Fuel Trim (FT) is derived from short term fuel trim value The Long Term FT is used for long term correction of fuel delivery. A value of 128 counts (0%) indicates that fuel delivery requires no compensation in order to maintain a 14.7:1 air to fuel ratio. A value below 128 counts means that fuel system is too rich and fuel delivery is being reduced. The ECM is decreasing injector pulse width. A value above 123 counts indicates that a lean condition exists for which ECM is compensating.