The Long Term Fuel Trim is a function where the ECU can learn the correct amount of fuel required over a period of time so that the Target and Actual measured AFR are equal. Sometimes this is referred to as Auto-Tune. Both Narrowband and Wideband O2 sensors can be used for Long Term O2 Control, however a Wideband O2 Sensor is preferred. Long Term O2 Control can allow for fine correction of the Fuel Base table in areas that may not be obtainable during the tuning process, for engine wear over time, or for self-tuning for small modifications. Mapping is available up to 4D.
Enable Long Term Fuel Trim
Enables or Disables the Long Term Fuel Trim Function. When Enabled, new tables are available in the Navigation Tree. (Default = Disabled)
LTFT Max Enrich
Sets the maximum positive (enrichment) correction that the Long Term Fuel Trim (LTFT) will allow. (Default = 15)
LTFT Max Disenrich
Sets the maximum negative (enleanment) correction that the Long Term Fuel Trim (LTFT) will allow. (Default = 15)
Long Term Fuel Trim Rich Bias
Allows the Long Term to learn an amount richer than the Target to allow for a safe tune condition should the system revert to open loop control, perhaps due to sensor failure. The short term control would then correct back to the Target Lambda from this learned bias. To disable this function it should be set to "0". (Default = 3)
Long Term Fuel Trim Min Temperature
Sets the minimum coolant temperature before the Long Term control will activate. This is to prevent the long term table form learning values from a cold engine. (Default = 60)
Disable During Post Start Corr
When enabled, the Long Term control will be disabled when the Fuel Post Start Correction table is outputting anything other than 0%. This is sometimes required when the tuner does not wish to allow the Long Term control to function whilst a start-up enrichment is active. (Default = Disabled)
Disable During Coolant Corr
When enabled, the Long Term control will be disabled when the Fuel Coolant Correction table is outputting anything other than 0%. This is sometimes required when the tuner does not wish to allow the Long Term control to function whilst the engine is not at full operating temperature. (Default = Disabled)
Resets all Long Term correction tables back to zero.
Apply to Base Table
Applies any Long Term corrections to the Fuel Base table, and after applying these changes it will reset to zero. When a second engine bank is being used, the Long Term system will apply the difference between the two banks to the Fuel Base table, and any remaining differences will remain in the table. All values that were equal will reset to zero. This must be done in this way due to there being two Long Term correction tables, and only one Fuel Base table to apply to.