Tranny slip.?.?

[cleatus12r]

Originally Posted by F150 Man 4Eva

Well on my ride home from work today I decided to show OSS and TSS on my parameters. I was surprised to see how far off from eachother they were. But given, I know nothing about these values or what they stand for or what they mean...nothing. I am looking for some insight on how much slippage is normal. It seemed that at low cruising speed (30) in 3rd gear..they pretty much matched up. When accellerating...way off. While cruising at 60 or so they were like 600-700 off. Can anyone help me understand this?

Yep. It's easy.

In first gear the turbine shaft speed will be about 2.88 times the output shaft speed.

In second gear, the TSS will be about 1.55 times OSS.

In third gear, they will be the same.

In fourth, the TSS will be LESS than the OSS because of the .71:1 overdrive.

When the torque converter clutch is applied, the engine RPM should always just about match the TSS.

The sensor inputs to the PCM have to do with the gear ratios in the transmission and the computer's way of self-diagnosis to determine whether or not there is slippage and whether or not the commanded shift actually took place.