I don't know, I thought an EX transmission was worth a tidy sum. Maybe you should try listing it on craigslist and see how much money you could get for the EX transmission. As for only getting 31mpg, that's seems low even for an EX. I think getting that federal ECU will help quite a bit but the way I like to do this is to get the car to meet its max fuel economy on what ever config it has THEN do a swap. Your car needs a tuneup and the easiest, cheapest thing you can do is replace the PCV valve.
Your car needs a tuneup and the easiest, cheapest thing you can do is replace the PCV valve.
on my LX, this was not so easy. it(PCV valve) is under the throttle body, and my research has lead me to believe access is "easiest" going from underneath. removing the oil filter, gives such access. but, i recently changed the oil so...
my idle has been a little weird, so i decide to clean my IACV(idle air control valve). it's not real simple or easy, but while there, it is possible to reach and replace the PCV valve.
OP has a VX which has a manifold that is the same as the other 92-95 vehicles and while it's not super easy to access, you CAN access it from the top. In the case of my '98 LX, I had to remove the throttle body, throttle bracket, bend some coolant and vacuum hoses out of the way and then I was able to access it. I mean if you're going to clean out the throttle body and the IACV, then it's trivial to replace the PCV valve on your car. Let me know if you need any help with the cleaning of the throttle body and or IACV since I cleaned both on my Civic. If you're going to clean the IACV, be sure to clean the throttle body thoroughly as well. The passages in the throttle body will be clogged, including the idle screw and so it's a good idea to clean it.
The ex trans is worth more. Typical used prices would be $350 for the ex, while the vx can be had for about $150 from a private party. It will make a big difference in FE. I say it's still a good deal due to the actual labor exchange and it's a win/win for both of you.
I exit lean burn when my life is at risk.
1998 Odyssey 24.1 mpg average
1984 crx project now on the road