Hey guru's,
I'm back with another issue. A year ago I went thru my 4L60E and swapped in 5 gear planetaries, corvette servo, new solenoids, seals, bearings. It ran great up to a month or so ago. It started with the TC not locking in 4th when cold. When it warmed up after driving 5 minutes, it works fine. ECM is commanding and reporting locked when this happens. Ive just learned to go easy on it for the first 5 minutes until I see the RPM's drop when it locks.

I have another issue that developed now. under medium throttle, 2nd hangs and will not shift into 3rd unless you manually shift to neutral and let the RPM's drop under 1,500 then back to drive or slow until it downshifts into 1st. WOT works fine thru all the gears as well as light throttle (up to 20-25%). ECM shows its shifting as well as the solenoids are being commanded. transmission even reports its in the commanded gear when its actually in 2nd. The tranny is full of fluid and no MIL lights or codes stored. Ive attached 2 tune files, one with a good shift and one with a bad shift. I'm baffled.

Any ideas?

 

What's your shift pressure in your tune look like? Mine has done something similar (two different ones and even after being rebuilt) but I know it's not a trans issue. The stock up shift pressures leave a lot to be desired. Mine would only do it when towing the car. Adding pressure in the right regions can make the clutches clamp harder.

 

I added my current tune file. This worked for almost a year then this happened. I overlaid a stock tune pressure map and it was the same for areas I'm having issues in.