Q: Engine swap with Ej20x, Ecu question

asked by on January 01, 2017

HI, I have a 2005 Subaru Legacy 2.5 GT with a blown motor due to turbo failure, I found an Ej20x motor to replace it, but it's a japan imported motor. I was wondering if i would need a japanese ecu to go with the motor, or would mine work if i just transferred it over to the new motor? Thank you.

My car has 232053 miles.
My car has an automatic transmission.

I will describe a scenario that will work and you can then judge your actual circumstances based on that. The initial issue is not the "country of origin" but rather whether the block and heads are identical, in every respect, to what you already have, preferably with the same casting numbers. If identical, sensors and all of the specific PCM controlled "parts" can ALWAYS be carried over to a replacement engine such that your existing PCM will work. If the casting numbers are not the same, you have to check and make sure that that all the mounts (both mounts to the car frame and accessory mounts) are identical. If they are not identical, obviously it will not work because it will not fit. If the cylinder displacement, firing order, and valve train, INCLUDING any variable valve timing controls and mechanism, are all identical, and all mounts are identical, you should be OK. But, again, a final consideration is your present PCM is of course working from a particular complements of sensors, and a specific engine wiring harness, so long as the wiring harness to the new engine as well as all sensors, controls, and air induction, not to mention the fuel injectors, are all IDENTICAL in specification and function to what you have it should work. Of course, to ensure that, it is possible to simply transfer the injectors, sensors, and controls from your present engine to your new engine. Basically, everything your present PCM controls on your present engine has to be the same "complement" that appears on the replacement engine. The foregoing is what you have to be cognizant of. If you need assistance with installation or start up, by all means feel free to contact YourMechanic to obtain the services of a certified mechanic in your local area.

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