Need Help to Diagnose Transmission Issue

[t-topflyer]

Working on a turbo buick in which the 1-2 shift is fine. The 2-3 shift if it's in D and especially the 3-4 shift in O/D seems to happen too soon sometimes and lug and stay in the high gear when it shouldn't. Doesn't slip or have any other issues that I can tell. Replaced the tcc solenoid and adjusted the TV cable but it acts the same.

Transmission has some mods such as a 10 vane rotor, hardened steel vane rings, 500 boost valve, billet super servo, kevlar band, hp clutches, modified seperator plate, modified accumulators, hardened sun gear shell, heavy duty pressure regulator valve and spring, double pump slide springs, rebuilt hp torque convertor 2800 stall

Car is othewise completely stock chip and all. Any ideas?

 

[t-topflyer]

Anyone???

 

[robertmee]

My uneducated guess would be valve body issues

 

[SSedan64]

Throttle valve binding/sticking, Governor problems, more guesses.

 

[t-topflyer]

Thanks. That's a start. Anyone know what all is controlled electronically? Would any of those upgraded parts be an issue such as the higher stall convertor? Read somewhere adding some extra fluid may help. Please forgive my lack of education on this I don't know a lot about automatic trannys and am trying to become educated.

 

[77 cruiser]

Lockup is the only thing electroniclly controled. Are you sure it's not locking when it shouldn't? Try unplugging the wiring & try it.

 

[t-topflyer]

Lockup is the only thing electroniclly controled. Are you sure it's not locking when it shouldn't? Try unplugging the wiring & try it.

seems to shift just fine if i do this. any ideas on how to get it to work with it hooked up correctly?

 

[t-topflyer]

Unplugged the wiring and it seems to function normally. So, the TCC seems to be locking and/or staying locked when it shouldn't.

What would cause this and what do I need to do to correct it?

Any tips would be much appreciated. Thanks

 

[77 cruiser]

Sounds like their is power to the solenoid all the time & as soon as it shifts to 2nd it locks.
Check the wiring for power at the A termial I believe.

 

[SSedan64]

TCC Apply Valve
This can cause lockup immediately after 2nd gear change also>> http://www.sonnax.com/announcements/77805-K.pdf
Check wiring for constant 12V to Solenoid as stated above 1st.

Sonnax Transmission, Torque Converter, Performance, Driveline Parts :: Transmission :: General Motors :: 200-4R