Shift Quality

[Power Hungry]

On the power reduction, many folks complain about the "dive" when the truck shifts and prefer to have the torque reduction removed. On some performance programs, we eliminate the torque reduction, but on tow programs we don't... for obvious reasons.

As for the Shift Slope and Offset, here's how it works:

The PCM calculates a specific amount of torque output based on the calculated torque table. Let's say this is 372 Ft./Lbs for a given Throttle Position and Exhaust Backpressure.

You multiply the torque by the slope for that particular gear to generate a Line Pressure PSI value. Using your towing (1st program) example above and assmuing 2nd gear...

372 * 0.1719 = 64 (63.9468) PSI

Then you add the offset...

64 PSI + 0 PSI = 64 PSI

64 PSI is what the PCM will set the EPC regulator to for main line pressure in that particular gear.

Make sense now?

[cleatus12r]

OH MAN does it ever make sense now!

Which is why adjusting the torque table map makes such a difference in pressure all by itself.

Thank you Bill.



I hope you had a good evening and that you and Corey as well as the kids have a great start to 2010!

[Power Hungry]

Glad to be of assistance. You and Jess (and the horses and "Dinner" and the rest of the brood running around on the farm) have a fantastic New Year as well. May God bless you and provide everything you need.

Take care.

[907DAVE]

How much does the Adaptive Shift Strategy's play into this?

What all does it change, just shift pressures?

[cleatus12r]

The thing about the 4R100 vs. the E4OD is the addition of a turbine shaft speed sensor (input shaft speed) that allows the PCM to actually see the time (duration) for any shift. Yes, the PCM can increase or decrease the line pressure during a shift to accomodate the desired shift time. In the parameters, I think that the PCM is allowed a 20 PSI window + or - to compensate.

Then why change the TV pressures during shifts?
Go back to the IPR map vs. desired ICP way of thinking.

[907DAVE]

I gotcha.

I guess if you know what the computer is trying to accomplish and how it is doing it, tuning become a little more cut and dry.

[907DAVE]

What is the purpose of the Converter Lock Torque parameters?