You've got me confused. What are you calling a "VCV" valve?
There is a vacuum modulator, a "kick down" switch and the control rod on the transmission.
The modulator has a vacuum line leading from the rear of the intake manifold to the RH side of the transmission.
The control rod leads from the accelerator linkage to the RH side of the transmission.
The kick down switch is mounted beneath the accelerator pedal.
The only one of these which would/could prevent the transmission from shifting would be the kick down switch and I doubt it would prevent up-shifts but I've been wrong before. Try disconnecting it.
The smoke machine is a good idea. If you decide to make one I've got a surplus of the wire I'd be happy to send you. No charge.
Here's an DIY one. It is basically the same as the one I made.
https://www.youtube.com/watch?v=Np_duzsaZxI