2.5 h4 out ej25 in
Asked by Justin Jun 06, 2018 at 05:48 PM about the 2006 Subaru Impreza 2.5i Wagon
Question type: General
I am swapping out a 2.5 h4 with blown headgaskets in an outback and
dropping in an ej25 from a legacy, glancing at the o2 sensor positioning i am
going to have to re route the wiring due to catalytic converter differences. Is
this as an easy task as just simply rerouting and are there any other small
surprises I am going to run into? They are both manual and everything else
looks like a direct swap.
11 Answers
The biggest surprise you may get is not passing smog inspection. What year engine are you swapping in?
I am swapping in an ej25. You think the smog inspection won't pass even though I will have the same number of 02 sensors? Would that be because of the positing of them in comparison to where they are in the old exhaust? Would switching out the ecu's help that issue?
TheSubaruGuruBoston answered 5 years ago
I'm also wondering if you have to match the ECMs. Also, many 2004-2005 (pre-VVT) 2.5i had FIVE O2 sensors, making even normal running tricky. If your pair of systems have three sensors you have a greater chance of success. But you may have to match the ECMs....
it is an ej25 engine out of a 2006 impreza into a 2005 outback
I have no clue, I wouldn't even know how to tell. I'll look up how decipher it and get back to you with an answer.
If one car is VVT and the other is not you will have issues. In that case you would need the wiring and the computer at a minimum. What state are you in? In California your efforts would probably be doomed.
I am in Vermont which has similar emission regulations as Cali. Since one is an 05' and the other is an 06' I am hoping for both have variable valve timing as it was standard after 2005? If so then I take it the ECM wouldn't matter. As far as I seen the way to know if it does is weather it possess the VVT solenoid with a blue connector below the air intake. Is that the correct method I should be using for finding out if they both have them?
If one engine has the connector and one does not then you have a problem. I cannot speak for Vermont but here in the land of fruits and nuts ANY variation from what things are supposed to be like results in failure. A referee can inspect the car and allow the change or not.
TheSubaruGuruBoston answered 5 years ago
In VT BOTH engines are ok, as the VVT simply debuted in 2006. YES, you can easily tell the difference by the existence of the solenoid on each head corner (left front and right rear). I would NOT interchange them, however, as FOR indicated, there'd be harness, ECM and O2 sensor issues. In CA emissions states the 2004 and 2005 2.5i simply had a more convoluted 5 O2 sensor emissions system, which was simplified for 2006-2009 with the VVT design. I'm not even sure if interchanging the heads would help, either.
