why won't my car downshift?

[shady1504]

Whenever its in fourth gear like on the highway and I floor it the car won't downshift, so I have to downshift manually. Anyone know why it does this? Shouldn't it downshift into 2nd when I hit WOT?

[SeVeReDiStOrTiOn]

OoOoOh the legendary "dead spot" in the 4l60-e:yay: You either have to get a higher stall TC or find out which speeds kick down and which don't. I know anywhere in the 60mph range and it kicks down hard...40-50 it never does...and 28ish and under it'll slam into 1st hard. Just spend some time crusing on a open road at different speeds and see where yours kicks down.

BTW...did you swap gears/rear from a M6 car?

[shady1504]

Yes I swapped rearends from an 02 Z28 M6 but I kept my axles.

[Ed Blown Vert]

Did you re-tune the PCM for the new gears?

[shady1504]

Yes I did reprogram it for the new gears. Can I program it to downshift from 4th to 2nd?

[mrr23]

going from 4th to 2nd at 80 mph isn't a good thing to do. it should go to third, though.