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Old 12-29-2018, 02:41 PM   #1
Scooby Newbie
Member#: 495716
Join Date: Dec 2018
Default NON AVCS ecm on JDM Single AVCS EJ205

Hey guys I need help shining a little light on this topic. I own a 2005 WRX and I blew up the old motor sooo, I put the JDM EJ205 back in. The new motor came with the matching ecm so all I really had to do is buy the AVCS harness from IAtuning. Well the down side to going that route is the fact that there is very little tuning options available, and apparently the JDM ecm is tuned to a higher octane than we in the US donít have access to at the pumps. So what I have decided is running everything USDM. I put the USDM ecm back in the car and the only code Iím pulling is the PCV p1491 and thatís it no other code issues. I just need some insight on what Iím doing wrong, or what I should do different. I know I can use the intake cam gears off of my old USDM motor, but is it really needed? Input Would be greatly appreciated. Iím looking to go stage 2+ I just want to make sure everything is kosher before I do thanks in advance
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Old 01-03-2019, 12:37 PM   #2
Scooby Specialist
Member#: 111755
Join Date: Apr 2006

whether you run the JDM ecu or not doesn't matter to the engine. Yes, the JDM ECU has more aggressive timing designed for JDM RON Octane standards, but your JDM EJ205 is probably 9:1 compression ratio. If your USDM ecu is going to be running high timing advance, it will also have problems hitting those targets without ping or knock.

The usdm ecu just has COBB AP as another available tuning option, where COBB doesn't support JDM ECU's, however you should be fine if you were to go open source. check out rom raider. if you are going to have the ecu tuned, the timing will be changed either way no matter your ECU.

now for your codes, you are only seeing 1 code because all the AVCS features are not part of the USDM ECU program. The actual hardware and trouble codes do not exist in the USDM ECU.

At the very least you will see 4 codes since the AVCS system is not getting power:

AVCS CAM Sensors

AVCS Oil Solenoids

The harness is pretty straught forward (I struggled with it for days, but i botched it, and finally with the correct parts, i made a solid harness) and the engine with AVCS is a whole world of difference unless you are above 4k rpm every time you press the gas.

Check out romraider.com any tuner should be able to get you to your targets with a tactrix cable.
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Old 01-15-2019, 10:24 PM   #3
Scooby Specialist
Member#: 453872
Join Date: Sep 2016
2005 wrx wagon


i would rather run the JDM ECU (with its stock tune), with fully functioning AVCS and let it pull timing for out fuel, than run the USDM ecu (with stock tune) on the jdm motor. if it were me.
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