I'm putting in a 4l80e in an fbody... with sepreate trans controller...
trans controller only has an output of pulses per mile
the pcm is looking for pulses per rotation...?
can somebody help me with the formula for the math..
I can enter in any value I want in the trans controller output and I can enter anything I want in the tune...so I'll just pick #'s that make sense....
any help is appreciated
and if it helps...
running a 3.42 rear end gear
well... simple math...Originally Posted by skippy
t56 tune
vss is normally 17 pulses per rotation
17*3.42 gear =58.14 pulses per tire rotation
Mile is 5280 ft or 63360 inches
Tire size*Pi gets you inches per rotation
Stock size is 24.94
24.94*pi = 78.35132
63360/78.35132 = 808.6654 rotations per mile
rotation per mile * vss per rotation is 47015.8 pulses per mile
tell the trans controller to output 47016 pulses per mile and it should match up dam close...
make sure you have your Fbody file set to 17 pulses per rotation and 47016 pulses per mile and it should give you an accurate speed if you are on stoc tires...
if not stock tires, just do the math...
-Scott -
Pretty sure the VSS on a 4L80E is 40 and not 17. Just read that somewhere.
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