I have done some research and looked and googled everything I can imagine. However I have yet to find an answer. I have a 93 FD automatic that has now had 3 transmissions installed. The first one stopped working after only owning the car for 24 hours. The 2nd and 3rd trans have both quit shifting into overdrive. The car is equipped with Apexi power fc, exhaust, intake and that's really it.
As stated above it has run and shifted at one point however now it will only find Overdrive on occasion. I have spoken to a few that seem to think it could be a cooling issue. Some say transmission is failing. Any input would be greatly appreciated! If this has been covered somewhere and I am overlooking it please feel free to link me to it so I can read!

 

are u running just power fc or with Banzai adaptor as well?

 

No direct experience, but I think overdrive lock-out is a side effect with the PFC on an automatic transmission. So it might not be the transmission, it may just be the ECU. I doubt whether or not your using an adapter makes any difference.
You could search around in the 3rd Gen. Section and see if there are any fixes to it. Or consider simply moving back to the stock auto ECU. The stock ECU should be able to handle those light performance modifications just fine as long as you keep it at stock boost levels.
If you choose to go that route but didn't get the stock ECU with the car, I'd post a WTB ad in the 3rd Gen. Parts section. They should be plenty cheap (I'd guess something <$50). And on the plus side, you could sell that PFC for way more.

 

A side note....if the previous owner has removed emissions or removed the OMP, I would NOT recommend returning to the stock ECU. It will throw codes with a CEL. With no OMP it will be in limp mode.