just installed an LS6 and built 4l60e in my brother's '05 ECSB. Tranny seems to work well at all part throttles (although it shifts quite hard). But when you hold it to the floor it just keeps accelerating till rev limiter and sits there until you let off then it shifts. I've been playing with the tune and can't seem to get anywhere. Could the new trans be at fault?

 

What gears is it doing this in? I had the exact same problem and it turned out to be my 3-4 clutch pack going out

 

all gears!

 

If its doing it in all gears and the shifts are quiet firm I would say its unlikley a trans issue .
Give wheatley a holler maybe he can give you some ideas.

 

What are guys doing with the shift pressures in the tune after a shift kit install? They were bumped up a bit in his old tune but it shifts quite hard with the kit in. Oh and it has vette servos too.

 

Not sure about performabuilt but FLT recommends all tables be reset to stock values, especially the pressure tables.

 

 

if you had a tune before with out the shift kit, then put the line pressures back to stock.

You can go lower than stock on the 2500 and below for normal granny driving or around town.

 

Right on, also i was reading on someone's 4l80e thread that he was zeroing the WOT shift vs Speed table and just using the RPM table. Has anyone done this?

 

It is possible, and I dont think there is any problem with it, but I just match them anyway, only takes a few seconds. After a certain TPS, the computer assumes WOT, and since the WOT shift table is 0, it goes back to the normal shift table which goes up to 100% TPS.