The TCU has the ability to...
The TCU has the ability to offer user-selected data logging for tuning and diagnostic purposes. The parameters that you want to record need to be set.
The TCC should be evoked at a road speed and engine rpm that can accept it without intrusion to the vehicle or passengers/driver. The TCC should easily disengage, but not without any throttle movement. It should require a certain amount of opening. If the TCC is made too sensitive, it will constantly toggle on and off, and become an annoyance.
Minimum MPH for TCC Lockup: This table assigns a road speed and works in conjunction with the parameters table to fine-tune operation. Depending on your vehicle, a good rule is to have the TCC lockup at light load at around 35 mph. Remember, the mph table will only be allowed to lockup the converter after the parameter tables are satisfied. In calibration parlance, these are called "flags," so the values in the parameters table need to be met first, and then the road speed to engage the TCC.
TCC Lockup Rate: This manipulates the calibration so the converter can be engaged without excessive slippage, yet not be intrusive.
Converter Lockup Delay: This works along with the parameters setting, and allows slight throttle and load modulation without evoking a change in TCC status.
Once a data log is complete,...
Once a data log is complete, the values can be seen in graph form with a different color for each parameter.
This sets the maximum road speed at which the transmission can be forced into a lower gear with the shift lever.
Slapstick Performance: This can be used to connect additional switches to control shift points, such as nitrous activation or to tune manual gear changes.
Force Motor Tables: The TCU allows line-pressure calibration for all gear changes, and those tables can be found under this heading. Again, at light load the line pressure should be sufficient to create a nice shift without clutch slippage, and increase as a function of engine torque output.
Conclusion
Though tuning the 4L85-E can be a very rewarding experience, it's best to first drive the Pontiac under varied operating conditions, noting any undesirable characteristics, if any, of the transmission's performance. Then you can use the tuning ability to make it into the automatic that you always wanted-one that enhances the excellence of a Pontiac engine.
In our application, the Performance/Economy...
In our application, the Performance/Economy mode, which raises the line pressure is evoked by a dashboard-mounted valet key switch.
Editor's note: Now that it's all finished, we can explain why Part IV of this story took so long to complete. When the GM Performance Parts TCU originally arrived, it was sans the CD or the USB-to-Serial computer cable to program it. (Don't worry: Yours will have them and our situation will be completely avoided.) We contacted GMPP and were told that we could simply download the program from the TCI website and we wouldn't need the CD.
Using the store-bought USB-to-Serial cable that Melvin Benzaquen, owner of Classic Restorations, previously employed to program a TCI TCU in a customer car, we tried to get started on the 4L85-E SuperMatic. It wouldn't work. The computer and the TCU would not speak to one another, and error codes ensued. On a long Saturday, we tried two cables and three different laptops-two PCs and a Mac-but nothing helped.
GMPP recommended we call TCI. Russell Culver, a tech at TCI, was very helpful. He said it was most likely the cable, but he told us to send him the TCU just to be sure. We soon learned that the TCU would only work with the TCI and/or GMPP-provided cable, despite the fact that these are not proprietary cables. Russell sent it back with the cable he used, and we were golden. See? Magazines run into the same issues that you do.
The moral of the story? Only use the cable that is supposed to be supplied. Ed.