[Eva5qu32]

Hello!
My2005 forester 2.5xt automatic scoobie died and was resurrected with a WRX STi engine. It runs well but I think it needs to be tuned. When I crank the Engine the car starts just fine but it tends to rev up here and there when its idling.Also i noticed my cruise control light starts blinking after driving for a while any ideas of what this might indicate? Is there something i can buy in order to tune my car like an acces port and some maps? I am completely clueless all I know is that somehow i have an STi motor in my car and I just want it to run as best as possible. Please note that I am car illiterate so please have patience with me.
thank you all!

 

[mkeskater414]

I think your best bet would be to take it to a tuner and have them tune the ECU for you.

Having an Accessport wouldn't be a bad idea as well. The tuner, though, will be of the most help and will make the car run to its potential.

 

[TFBHTMFSNE]

I hate to ask, but:

When the STi was swapped in, what else was changed? ECU? Harness?

 

[Eva5qu32]

nothing really. just the engine

 

[Subie 2003]

nothing really. just the engine

Me thinks that may be your issue

 

[RAPTR]

Yeah^^
You need at least a matching ECU to that engine for that swap to be successful or at least you need to be really good with wiring harnesses. It also looks like now you have AVACs to deal with. I don't remember if the 05 2.5xt had AVACs. I'd definitely buy a matching year STi ecu and start from there. But also since you have a AT that is going to throw a bunch of issues at you too. Good luck on this journey if you want to stay with this engine. Lots more research, research and research and your wife yelling at you to get off the computer.

 

[EvilDan]

I'm sure you probably have the ECU, hopefully, and if that is the case, then check for vacuum leak.

 

[Blue Fox]

First, you CANNOT swap in an STi ECU as you have the 4EAT and the STi had the manual, won't work.

04 and 05 Stock XT's have AVCS, so that's not a worry.

Essentially, you have the EJ257 motor in your car, stock XT's have the EJ255. Only difference is the design of the pistons if I remember correctly, so a tune is what you "might" need...

But first, two questions.

1. What year STi is the motor from?
2. Did you re-install your stock TD04 turbo, or did the engine come with a VFxx STi turbo, and that is what is installed now?
3. If the cruise light is flashing, odds are the check engine light is on too. What codes are being displayed when you plug in an OBDII reader?