Since installing my mailorder tune and monitoring my fuel trims, I've noticed that my long-term fuel trims are ALWAYS in the negatives - usually pretty consistently between -5 and -10 - but sometimes as much as -15. WIth my stock tune, the LTFT seem to be dead on.
After reviewing the differences between the stock and mailorder tunes, the only thing that I can see that could cause negative LTFTs are changes to the "MAF Airflow vs Output Frequency" table (values are higher in my mailorder tune).
So I actually have two quetions:
1. Are consistently negative LTFT really something that I even need to worry about?
2. If so, is it safe to revert the "MAF Airflow vs. Output Frequecy" table back to stock values to see if that brings my LTFT's back to 0'ish? I'm just not sure if modiying this table by itself can cause any issues with other parts of the tune - or is this table truly "independant"?
Other than PE-related changes, I really don't see any other changes that would affect fuel ratios in the mailoder tune.
Thank you!