Fastmax

I have a 1994 corvette LT1 that after the latest round of mods is overpowering the tranny on the 4-3 kickdown. But only if I let it kick itself down. What happens is when I stomp it in high gear, and it kicks down into third it slips by about 3-400 RPM. However....If when I kick it down I manually pull the lever down into third, it does not slip. If I nail it while it is in third it does not slip. If I run it wide open through the gears it does not slip. This problem only happens on automatic kickdown. This leads me to believe it is applying more line pressure by my manually pulling it into third. Short of taking it apart to rebuild it, I notice there are 3 tables in tunercat that are 2-1 downshift pressure modifier, 3-2 downshift pressure modifier, and 4-3 downshift pressure modifier. The only one of these that has any numbers in it is the 3-2. The other two are both filled with zeros. Can I use these tables to correct this issue? If so what do I put in them? If not is there another tuning adjustment I can try?
Thanks
Roy

FLT

iTrader: (1)

Try to lightly tap the brake pedal before doing the 4-3 kick down while keeping your foot steady on the gas. This will disengage the TCC. I believe you might be seeing the converter clutch being disengaged when doing this. It is possible that your 3-4 clutch might be slipping but as I mentioned above this is a possibility. Also when you manually place the shifter back to 3rd the overrun clutch comes on and this does help aid the 3-4 clutch if in fact it's slipping. Vince

tptransmission

Vince is correct right along with the addional capacity of the overrun clutch you get a boost in commanded pressure when you manually downshift.

Fastmax

Well that makes perfect sense. Thanks guys. Its definitely not the torque converter clutch. I guess I am running on the edge and if I cant keep my foot out of it then it wont be too long before I will be taking it apart for a rebuild.
Do you think the 383 I have in the works will help at all?