• iWire Subaru Wiring Services

EJ20X and EJ20Y Dual AVCS

Updated: Oct 7


We’ve been getting this question a lot lately,

"I purchased an EJ20X or an EJ20Y engine and I want to get the Dual AVCS (exhaust side AVCS) working in my car."


The short answer is that unless it's a very specific case, the exhaust side AVCS is not going to be functional.


Want to confirm your engine is an EJ20X or EJ20Y, check out our engine guide.


EJ20X and EJ20Y Engines

These engines are becoming more available and are tempting due to the low mileage and low price point. There is nothing wrong with the engines themselves and they are a pretty good setup but a lot of the benefits of these engines come from the exhaust side AVCS. The problem with the exhaust AVCS feature is that there isn't a simple adapter or jumper to make it work. The reason for this issue is that the only ECUs which have the capability to run exhaust side AVCS are CANBus equipped or are standalone ECUs and neither of these options are simple additions.


What Happens if I leave the Exhaust AVCS Disconnected?

Nothing really. The engine should not self destruct because the exhaust AVCS is not active. The issue is that the cam gear is designed to move/adjust based on the AVCS solenoid's request. Without that solenoid active it tends to oscillate with changes in engine oil pressure. The best solution is to cap the passage but you must be careful to do it in the right spot or you will starve the head of oil. We suggest talking to a local shop/engine builder because they are more equipped to answer the question as to the best way to do this.


Cases Where Dual AVCS is Not Likely an Option


Non Turbo Cars

If you have a non turbo car and are trying to swap in the EJ20X or EJ20Y, you will not be able to get the dual AVCS to work at this time. iWire recommends putting a single AVCS intake manifold and harness onto the EJ20X/Y long block to make it function like a single AVCS platform. From there we would merge the harness for the matching ECU and bulkhead harness to the single AVCS intake manifold chosen. The final step would be to contact a local shop or mechanic for the best solution for your project to block off the exhaust AVCS ports.


More about Single AVCS swaps into non turbo applications can be found here.

Drive by Wire Turbo Cars

If you have a turbo car such as a 04+ Forester XT, 06+ WRX, 07+ Legacy GT, or 07+ Outback XT and are trying to swap in an EJ20X or EJ20Y, you will not be able to get the dual AVCS to work. iWire recommends putting the intake manifold and harness from your original engine onto the EJ20X/Y long block and ignore the exhaust side AVCS. The final step would be to contact a local shop or mechanic for the best solution for your project to block off the dual AVCS ports.


More about this can be found here


Cable Throttle Turbo Cars

For the 2002-2005 WRX and equivalent models, this would be a similar solution as the non turbo platform due to the differences in cam position sensor type between the 16 bit and 32 bit ECUs. The quick and dirty option is to put the 2.0 intake manifold and harness on the new long block, add the bracket for the front cam position sensor and ignore the AVCS all together. Outside of that it would require an intake manifold swap on the EJ20X/Y engine to a single AVCS platform and then a harness merge on the 2.0 WRX to run the corresponding 32 bit ECU and engine harness.


Our suggestion for these applications is to stick with the cable throttle platforms from similar year JDM WRX and STi models. More compatible engine info can be found here.

Cases Where Dual AVCS is a Possibility


2005-2006 Legacy GT or Outback XT

If you purchase the correct EJ20X/Y with 2 wire camshaft position sensors on the exhaust side then you could get the dual AVCS to work by running the JDM ECU and purchasing our exhaust AVCS wiring kit.


Click here to learn more about this option

2008+ USDM STi

This car already has Dual AVCS so you can utilize the USDM STi intake manifold and wiring harness on the EJ20X/Y long block. We're not sure this would be an improvement over an EJ257 dual AVCS platform, but it would work as long as the exhaust side cam position sensors are the 3 wire type.


Details can be found here.


Standalone ECU

If you are DETERMINED to get the Dual AVCS to work and your car is not one of the exceptions above where a stock ECU is possible, you could run a Standalone ECU. This would increase the cost of the project and could be an issue if smog/emissions are a concern. Due to the expense, complexity, and potential smog/emission concerns, iWire does not recommend this option but we are happy to wire up any project you like so if you want to go the standalone ECU route, please contact us directly.

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