LTFT - range vs + range lean rich question

[mvvette97]

I always assumed that when the trims are running in the negative range the leaner it is and positive is richer. Is this correct or am I bassackwards?

[Aloicious]

I always assumed that when the trims are running in the negative range the leaner it is and positive is richer. Is this correct or am I bassackwards?

bassackwards. negative LTFT's mean that the PCM is removing fuel, i.e. you're running rich, positives are the opposite. thats why when you're tuning from the trims (i.e. without a wideband), you want slightly negative trims, so you're running slightly rich, for safety.