Acceptable % between LTFT"s
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Joined: Apr 2002
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From: Cave Creek, AZ- Canada Also.
Acceptable % between LTFT"s I have Long Tube SLP headers and the car has been tuned. My LTFT on bank 1 seem to run about on average 5.XX to 7.XX %. On bank 2 they run from 3.XX to 5.XX %. It seems to average about 3.XX TO 4.XX % between banks and bank 1 is always leaner. Now I have checked for leaks and nothing. I swapped O2 sensors and have sprayed carb cleaner in areas I thought may cause a leak ( WHILE LOOKING AT MY PREDATORS LTFT #'s ) while doing this no spike in numbers.Is it because the passanger SLP header has a weird loop in one of the collectors or do I need a retune to bring the numbers tighter??
Top header is the passanger header.
Thanks
Top header is the passanger header.
Thanks
Last edited by 99SSragtop; Oct 23, 2007 at 05:18 PM.
Fuggedaboudit.
First off, stock fuel trimming bundles up a lot of
not-similar operating point feedback into coarse
"bins". The low-flow parts are very temperature
sensitive and plumbing differences alone can drive
bank-bank mismatch (one sleep and one awake).
You can tighten it up by using all of the fuel trim
cells (not half, like stock) and crowding them down
to where closed loop matters (low RPM, low MAP)
to get trims that are local & accurate rather than
big buckets of slop.
If you see trims continuously creeping as you sit at
idle then you can also have basic thermal problems
needing either hotter O2 sensors, thermal control
(wrap, standoffs, open up the vents of the sensor
tip, etc.) or both.
I wouldn't waste my time looking at couple-% skews.
Get to 10% (control range is 25%) and you're maybe
seeing some real (most likely fuel delivery or misfire)
mismatch contributor.
First off, stock fuel trimming bundles up a lot of
not-similar operating point feedback into coarse
"bins". The low-flow parts are very temperature
sensitive and plumbing differences alone can drive
bank-bank mismatch (one sleep and one awake).
You can tighten it up by using all of the fuel trim
cells (not half, like stock) and crowding them down
to where closed loop matters (low RPM, low MAP)
to get trims that are local & accurate rather than
big buckets of slop.
If you see trims continuously creeping as you sit at
idle then you can also have basic thermal problems
needing either hotter O2 sensors, thermal control
(wrap, standoffs, open up the vents of the sensor
tip, etc.) or both.
I wouldn't waste my time looking at couple-% skews.
Get to 10% (control range is 25%) and you're maybe
seeing some real (most likely fuel delivery or misfire)
mismatch contributor.
