I am on my 8th bin file, tuning a 350 with a 4l60e tranny. On my last datalog the truck ran as well as it ever has but at very low throttle about 40 mph the engine surges up and down like it is looking for an upshift. It is actually in 4th gear but after looking at the tranny data in datamaster it is the tranny slip running up and down. I assume this is causing the engine to surge up and down as the tranny load changes up and down. I need some suggestions on where to go from here. Is this a tuning issue or is this a tranny problem. I have done very little to the transmission tables and parameters. I could really use some help on this. I don't want to just start changing tranny parameters, because I don't want to tear something up.
Thanks, Charles

I am trying to attach a bin or the datalog but haven't figured out how yet...

 

sounds like it may be the TCC locking and unlocking, or hunting as its called.
im not familiar with the PCM and mask you have, but there may be a TPS qualifier for the TCC that needs tweaking.

of course that is just a guess and i may very well be wrong.

i've never attached a data log or bin, but i believe you need to add .txt to the end.

 

For '95 'Burb 4l60E tranny issues the Full Size Chevy forum is probably the better forum. They will be more familiar with that vehicle and the attendant issues with it.

RBob.