94/95 TT ECU in a 91 TT car

Turns out to be ridiculously easy. On the 94/95 ECU there are 4 plugs, I think this is why many people think it wont work in the 91 car which has 3 plugs. As it turns out the 3 plugs from the 91 harness fit into 3 of the for receptacles of the 94/95 ECU. Nearly all of these wires end up in the proper spot. That 4th plug on the 94/95 ECU is almost entirely for automatics and NA cars. The only wire I moved was the pin 101 on the 91 Harness to pin 58 of the 94/95 ECU. That wire is for the engine ignition signal. I never tried it without moving that wire.
So far I have put 50 miles on it with no issues, it runs great. I do not run a ISC at the moment so I have no idea if that would operate correctly with moving some wires. I also do not have a logger so I cant verify if timing is correct or if its lean or rich. From driving it everything seems to be good.
This is a good option to replace those junk 1st gen ECUs.

Sounds interesting. In for results after you get a logger on it.

Honestly I am not even worried about logging with it. I have yet to find a reason to think it is not doing everything it should. I am only running waste gate boost also. If I raise the boost I will log it.

Can you even log a 94 ecu with a datalogger? Aren't they OBD2 port?

Yeah, but you can use HHH's hybrid logging software, and I think there are a few more options as well

Are you able to get the active exhaust to work and the other OE functions?

My active exhaust doesn't work because a cable is broke. I will look a the pin outs and let you know. Anything that was on a 94 will work though, provided you wire it correctly if not already right. My active aero light is still on as it was before, but my active aero has never worked. I can raise my rear wing by hitting the switch and it drops when I turnn the key off. I have never really had the time to worry about the little extras. Just trying to keep the thing running.