LTFT Boundaries...what do they mean/control
05-23-2005, 09:21 PM
#5
i think it has to deal with how the fueling is broken down, into different catagories. the finer you make these areas the better the fueling will be. i noticed when i changed mine it was a lot easier to get the fuel trims in line, the 2000's are way out of wack
05-23-2005, 09:28 PM
#6
Originally Posted by WS6FirebirdTA00
i think it has to deal with how the fueling is broken down, into different catagories. the finer you make these areas the better the fueling will be. i noticed when i changed mine it was a lot easier to get the fuel trims in line, the 2000's are way out of wack
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05-23-2005, 10:26 PM
#12
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You have 16 cells available to trim closed loop
fueling. The less "space" any one has to cover,
the more accurate each can be. This is especially
true in areas where the airflow characteristics
change rapidly with RPM or MAP (like, say, the
low end on a big-cam car). What you don't want,
is one cell trying to comp out a wide space and
getting its value dragged up and down by driving
history, and always being late and wrong. This
is one thing that makes for bog-and-zoom engine
behavior on transitional throttle.
For my car I picked 1000, 2500, 4000 as these
seemed to fit my setup. But someone having a
low end drivability problem might want to crowd
it lower. The main thing is to get them all in play.
You might start by looking at the LTFT histogram
and position the boundaries so you have more cells
divvying up the area where you see the largest
trimming being done, or the area where the trims
seem to vary the most.
fueling. The less "space" any one has to cover,
the more accurate each can be. This is especially
true in areas where the airflow characteristics
change rapidly with RPM or MAP (like, say, the
low end on a big-cam car). What you don't want,
is one cell trying to comp out a wide space and
getting its value dragged up and down by driving
history, and always being late and wrong. This
is one thing that makes for bog-and-zoom engine
behavior on transitional throttle.
For my car I picked 1000, 2500, 4000 as these
seemed to fit my setup. But someone having a
low end drivability problem might want to crowd
it lower. The main thing is to get them all in play.
You might start by looking at the LTFT histogram
and position the boundaries so you have more cells
divvying up the area where you see the largest
trimming being done, or the area where the trims
seem to vary the most.
