RoaringTurtle borrowed my 97 gs-r ecu to go to the smog ref, and I've been using his 98 ecu. After a day of driving, the cel popped on. When I jumped it, it gave code 91-Fuel tank pressure. And, when I checked it with a scan tool, it came up as a code 90-Evaporative Emission Control System.

I was thinking either:
1) the ecu is faulty
2) the 98 isn't compatible with the 97
3) damn, I have a real problem

Guess we'll see what happens when I try the original ecu again.

 

My friend had that.. turns out the stereo place drilled his ground wire into the fuel tank.. so he needed a new fuel tank. I'm assuming that it's not that though right? Becuase you'd know if someone was doing work around your tank. Either way, that ecu should work fine w/your car. Good Luck man.