ECU for a 7afe in a 5sfe 1996 manual celica Options

[thebestofall007]

Hello all, I found a surprise in my 1996 Celica: It has an ECU for a 7afe manual transmission engine, however, mine is a 5sfe manual. The engine runs well, but gas mileage is not as good as it is supposed to despite replacing the cap, rotor, plugs, wires, and I get a P0141 code despite replacing the O2 sensor with an OEM Denso and checking the wiring connection between the sensor and the computer. The cables don't appear to be all spliced up, either.

Why would someone do this, and what would I have to do to replace it with the original (if this would fix the gas mileage and sensor issues)?

This post has been edited by thebestofall007: Oct 21, 2016 - 5:00 PM

[VavAlephVav]

Yeah, I'm surprised it works I'd guess it has all the same signals it's just going to be sending the wrong amount of fuel n such. As to why they did it, obviously because that's just what they could find and it worked. If you had to buy one of those things from Toyota back in the day it would have cost you a **** load of money. You can buy refurbished ones on Rockauto.com for $250 or if you get lucky you might find one at a salvage yard. I'd check for part-out threads too.