We've had a few people ask us about this swap lately so we thought we would share our expertise. This post talks about the nuances of putting an EJ20X/Y engine into a Legacy GT or Outback XT 2005-2009. The biggest difficulty is getting the exhaust side AVCS to work.
This swap is fairly straight forward to get it to start and run by just putting the USDM intake manifold from the Legacy GT or Outback XT onto the JDM engine. You could stop here and just tune for the new engine. To get the exhaust side AVCS working, it is a bit more of a challenge.
The USDM ECU does not have the capability to control the exhaust side AVCS so the JDM ECU needs to be utilized. This is not as simple as the earlier 02-05 WRXs running JDM ECUs that are plug and play (more about that here) because the Legacy models are immobilized. Below are the steps.
First Step - USDM Manifold
Swap over the USDM manifold and harness onto JDM engine so engine will plug in and run.
Second Step - Confirm Cam Position Sensor Type
2005-2006 Models
Make sure the exhaust side AVCS camshaft position sensors use a 2 wire sensor.
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3 wire camshaft position sensor on the exhaust side AVCS - Will not work because the ECU that goes with this engine is not compatible with the 2005 - 2006 Models.
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2 wire camshaft position sensor on the exhaust side - The immobilizer chip needs to be copied over to the JDM ECU so it will start and run.
2007-2009 Models
WARNING - The issue we have noted with these models is the USDM platform has more features than the JDM models for systems like the VDC and SI Drive. If you put in the JDM ECU you may lose some features even though it will run the dual AVCS.
Make sure the exhaust side AVCS camshaft position sensors use a 3 wire cam position sensor.
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2 wire cam position sensors on exhaust side AVCS - Will not work because the ECU that goes with that model of engine does not plug into the 2007-2009 harness.
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3 wire cam position sensors on the exhaust side AVCS - Plug in the JDM ECU, get the immobilizer matched up and run the car on the JDM ECU.
Last Step - AVCS Wiring from iWire
Once the camshaft and immobilizer chip has been taken care of we can build an AVCS harness from the ECU to the sensors and solenoids on the engine with a connector in between for easy service to get the AVCS working. If you would like this custom AVCS kit please Contact Us.
Learn more about the pros and cons of the EJ20X and EJ20Y platforms here:
