Alright I got a question here. My friend had an 02 wrx wagon with an intake, turboback and a custom tune. Well I graduated at Wyotech and he's still there. He called me up and said he let some guy drive his car and he crashed on an on ramp. It was totaled and he bought it back. He bought an 04 wrx wagon and swapped his parts over. He called me up and asked if he can just swap the ECU's since his old one is tuned. I told him I didn't think it was a big deal but I told him I'd ask around just to make sure everything was cool. Basically I didn't wanna tell him to do it then find out something blew because something else was different. What do you guys think? Does anyone know that it's definatley cool?

02 wrx....04 wrx wagon...if he can just swap the ECU's since his old one is tuned

nope.

nope.

What kind of difference is there that won't allow it to run right?

Yes he can swap a 02 WRX ECU into his 04 WRX. I don't know what the other guy is smoking, I have personally done it on a 05 WRX as well.

Yes he can swap a 02 WRX ECU into his 04 WRX. I don't know what the other guy is smoking, I have personally done it on a 05 WRX as well.

Yeah, that's what I figured. There really isn't anything that has changed and that's why I figured you could. If this other guy actually explained why you can't do it I may believe him, but some people just like to say things for the sake of saying things.

1.I am smoking Paulaner Hefe-weisbier
2. from what I've been reading, hardware isn't the same... later WRXs have a sonenoid that 02 doesn't have... there is a bypass, but you will have to edit/flash ECU anyway
3. despite the same mods, no car runs the same because sensors read differently

My impreza L ran off a 04 WRX Wagon ECU because that was the donor car. I later bought a 02 WRX ecu because the open-loop transition is way easier to deal with.

So yes you can just swap it out.

The above post is correct there is a one sensor change. The funny thing is that sensor doesn't do anything it is just a connection to ground. All the pins are the same except for one wire for the added sensor. You will not have A CEL going from 04 to 02 but you would have a CEL going from 02 to 04. And yes every car is different but it should work great. If your tuner tuned the car within an inch of its life then you may see a problem. But if that is true get a new tuner!

Sweet, thanks! I know people run Impreza L ecu's with 2.5 Rs swaps. One of my friends tuned his car in high performance class at school. So they kinda tune it towards the conservative side. I told him just to get his 04' ecu retuned at school since it's free and he's still there. We'll see what he does. Sometimes it's a pain to get on the dyno.