Yesterday while I was setting in the parking lot waiting on the wife and daughter to get their hair cut I pulled out the edge evo manual and started thumbing through it. I noticed that there are two functions that said if they are equl than your tranny is not slipping. One being the OSS(output shaft speed)( i think thats what it was called) and two the TSS(turbine shaft speed)(again i believe that was the name of it also). Anyways I had both of them switched over to my display for when we left and while I dont really know what I was looking for I noticed that most of the times the two numbers were off by several hundreds, but also noticed that when shifting to around third gear they sync'd up and ran equally and then to forth they seperated by a good distance. Does any of this make since and do you mind explaining what I should be looking for or if there is an adjustment that I need to make.

 

You know the answer already just haven't realized it. Look at how the tran is set up. You have the torque converter with a turbine on it to transfer power from the engine down the line. Then you have the various gears and a complicated mess of machinery that is designed to go faster while keeping the RPMs in the power zone. Each gear has a different ratio. As the truck goes through different gears (and ratios) staying in the ideal RPM the output shaft speed will vary with respect to the input shaft. The reason you were seeing the numbers only match up in 3rd is because that is your 1:1 ratio.

This should help illustrate how the two are related

 

And, Longshot left this out, but they will only match in 3rd gear if the Torque Converter is locked.

I think the Edge manual is very misleading regarding the TSS and OSS PIDs. Personally, I don't see much point in monitoring them.

- Jack

 

Thanks Longshot and Jack. That all makes since. I believe Edge should have just left that off as a display. I cant see any use for it as well.

 

Yeah they aren't very useful for anything besides troubleshooting. Just like the level 1 tranny tune. If you are pulling heavy loads and suspect tranny slip, that would be the first way to check.