Does anyone know if the LTFT values can be manually reset to zero? I was playing with Autotap yesterday and I was unable to do this. I turned the key on without starting and Autotap said my LTFT values were 3.9 and 2.5. I then started my bone stock car for a few seconds and the LTFT values were still about 3.9 and 2.5. I pulled the battery cable and left it off for 5 minutes. Put the cable back on and turned the key on and the LTFT values were 3.9 and 2.5. I started the car for a few seconds and Autotap reported the same 3.9 and 2.5 values for the LTFT values. The car also retained my radio presets, key fob programming, climate control temperature, and memory settings. This car must have some sort of flash memory that stays when we disconnect the battery.

I then turned the car off, turned the ignition on, pulled the 10A PCM fuse (#16) and watched all of the error messages flash. I turned the car off, put the fuse back in, and then turned the key on. Autotap still indicated LTFT values of 3.9 and 2.5. Started the car and got the same LTFT values.

I was thinking that resetting the LTFT values at the track right before a pass might temporarily help lean out some cars with bolt-ons that are running rich at WOT.

 

I don't believe so. The LTFT's are stored in the PCM and one of the values you can't change with a scanner.