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The main issue I have seen with this ECM, is that the circuit that grounds the fuel pump relay goes bad. And I know we have sent at least one ECM off to be "repaired" and it lasted a couple hundred miles. There is a list of people miles long on the internet searching for replacement ECMs for this vehicle.
So- this is the solution I came up with when my 93 failed in this way, and I have done it on at least one Rialta.
Take the fuel pump relay. There is a small terminal off to the side, that is the ground circuit for the relay. I have taken one of those relays, bent that tab off to the side so that it sticks out when the relay is installed- and run a short jumper wire from that tab to the ground point near the steering column. This will mean that the relay is active (and the fuel pump is operating) anytime the key is on (engine running or not) So if you are starting up the vehicle, and not sitting listening to the radio with the engine off, you are OK. And if you have a large gauge of wire that is not going to heat up (it is just a signal circuit, not load carrying) then you are OK and not about to burn down the van. But if you leave the key on, engine not running, I'm assuming the back pressures will kill the pump
The later vehicles had a slightly larger engine bay to account for the size of the VR6 engine- you will notice this if you get into one, the footwell area is more crowded, less leg length.
The main issue I can think of between the 93 and the 95 is that the 93 has an ambient pressure sensor built into the ECM itself. I don't know of anyone who has tried swapping the 93 in to see if it can be reverse engineered to make it work, but with the demand for 95 Winnie ECMs I can see it would be worthwhile to try. I was able to find an ECM for mine on Ebay when I needed one for less than $60, which isn't too expensive for a test considering there is no other option.
So what circuit has failed on your original ECM? Does it not start or run at all? Does it crank but not start?
Like I said, you are in territory that I don't know if anyone has the answer- If you frequent any of the Eurovan-specific websites and groups (VWVortex T4, EV-Update, etc) you will know that this is a common problem, yet nobody has come up with a definitive fix for it. Believe me, when someone finds a fix, it will ripple through this small EVC community, as it is such a common problem. But I am surprised that nobody has experimented with earlier ECMs (or if they have, the results haven't been positive and publicized!)