Originally Posted by
JaegerWrenching
The slope is a way to add a consistent percentage or amount across the entire torque range vs the intercept adds a specific PSI value. If you add 10psi to the intercept it will be more firm down low when compared to up high as more torque equals more PSI. Say you're asking for 40psi at X torque down low, now you added 10psi to your intercept 10/40=.25 or 25% increase in pressure, now look at when the truck is making 160psi 10/160=.0625 or 6.25% increase in pressure. You can see there is a big difference in the percentage of pressure added based on torque by adding only to the intercept. I feel there are many tables that determine what the pressure is going to be when shifting as well as some that may override your slope x torque + intercept value, and you're right that typically it chooses the lowest of the two. The 6r140 uses the power on upshifts table to determine line pressure during the upshift, this table seems to override almost everything else. I also think there are some more tables not defined by HPT that adjust the pressure ever so slightly in certain areas. This is where you need to have been a ford calibrator or engineer to really know where all the tables are, what they do and which ones to change.