what does stft% & ltft% stand for in live diag.?

Question

in the obd11 code reader what does stft&ltft% stand for?

Answer 1

STFT is for short fuel trim , LTFT is for the long fuel trim. In order for proper fuel control to happen the engine goes from lean to rich by adjusting the fuel trim.

 Here on this scan tool is the fuel trim event, as long as the short fuel trim with the long fuel trim both added together per Bank and is less than 10 % the engine is considered in fuel control, the closer to zero the better