EVO X Long Term Fuel Trim in Open Loop
- Brandyn Mowat
When tuning Evolution X vehicles the learnt Long Term Fuel Trims (LTFT) are applied during open loop fueling conditions. This behaviour is intended to allow open loop correction for the ambient and engine conditions and is useful if the calibration is exactly on point as it will cover the gradual change in fueling over time even in open loop.
This function is sometimes not desired especially on highly tuned cars or cars with sensors disabled. It is possible to get the Short Term Fuel Trims (STFT) to be used in place of LTFT when the vehicle moves from closed loop to open loop fueling.
This trim overwrite is achieved by changing the AF learning range set pointsThe settings that should be used are as per the below image.
This will not zero out already learned fuel trims, the ECU reset must be performed as well using the DTC tool or the programming window.
This side and onward effects of this modification are unknown and these changes are made at your own risk. keep in mind emissions will also be effected.