Long Term FT Bank 1 and Bank 2

The scan tool displays - 23 to +16 percent. Long-term FT is derived from the short-term FT value, and represents a long-term correction of fuel delivery. A value of 0 percent indicates that fuel delivery does not require compensation to maintain the PCM commanded A/F. A negative value, significantly below 0 percent, indicates that the fuel system is rich, and that the fuel delivery is being reduced. A positive value, significantly greater than 0 percent, indicates that a lean condition exists, and that the PCM is compensating by adding fuel. Thus, a decreased injector pulse width means the fuel delivery is being reduced, and an increased injector pulse width means that fuel is being added. Long-term FT tends to follow short-term FT. A value in the negative range which is due to canister purge at idle should not be considered unusual. The maximum authority of the PCM to control long-term FT allows a range between - 23 percent and +16 percent. Fuel trim values at or near maximum authority may indicate an excessively rich or lean system.