Just got my old car running with an 05 4.8 4l60e combo from a wrecked truck. I had a guy rework the harness and flash the ecu. The transmission shifts lazy and soft but when it was in the wrecked truck it worked perfectly fine. Could this be due to the ecu tuning? Maybe he put incorrect information in for tire size and gear ratio? Can shifts be firmed up through the ecu with a 4l60e? I would like to get it figured out soon so it does not damage the trans, thanks!

 

All of your questions (could be?)answered with yes. However, one of the big ones is how long did the 4l60 set up? I have seen built 4l60's **** the bed because of long term storage.

 

It did not sit very long. I guess I'm just wondering on a basic stock powertrain swap how much tuning should have to go into the transmission? Is it as simple as entering axle ratio and tire diameter numbers to make it work like it did in the stock low mileage donor vehicle? Or does it require extensive computer tuning to make it work properly? Thanks

 

Your transmission should work ok with basically no tuning. I think you have some other issue.