Chris is right....
Very correct!
In fact what it is telling you is converter effecientcy. We have a hard time explaning cause it is a little "backwards" than what one would believe. But Chris explained it as well as anyone could have without going into a whole nother debate about converter effeiceintcy. <<<( How the hell do you spell this word correctly)
But basically the more "fluid coupled" the converter is the higher the shift point can be.
Here is another thought....... that may not be the whole cause but part of and in conjunction with what was mentioned above,......Temp of oil discharged from converter can effect even more and that is.....Remember a converter under load is a big heat pump.
More heat is generated at stall under load. Both mainline and other required pressures decrease due to tempeture rising under the stall or load incurred under heavy boost. So in theory the oil thins enough to not have the "power" or "properties" to function shift valves, tv oil and/or gov pressure.( To some degree, not like it fails just slightly , lets say, late.) Also, by the time you reach same mph under more boost , the more G forces are incurred and filter can be uncovering or starving for oil return due to how much oil a quality converter will move and it cannot scavenge back to pan fast enough.
So in turn 3 or 4 factors can effect and/or cause this symptom.
Honestly.... This is exactly where we noticed the tractor hydrulic fluid and deeper pans, dramatically effected these exact symptoms. Temp was lower and viscosity was better, improving mainline pressure stability , in turn making the shift points more consistant.
Try it Chris, see if you notice any difference. Even if you just try one fluid vs another, see if you get a change. Sometimes, believe it or not, add a quart of 20-50 or 30 w motor oil to trans ATF and lube properties and viscosity properties will improve. You will see this by more stable line ptressures throughout tempature rise.
Whatcha think ?
Agree, disagree? Chris? Opinions?
Bruce
WE4