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Old 05-21-2018, 09:49 PM   #1
Kampfzentrum
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Default 2005 USDM STi ECU/Harness to V8 EJ207 - Potential Issues HELP!

Searched the boards, found about every other kind of combination between USDM harnesses and JDM motors, but no 2005 USDM STi ECU/harness to V8 EJ207 drivetrain. I'd love to do this and am wondering what potential issues are with these swaps.

I could really use the input, thanks in advance.
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Old 06-25-2018, 01:24 AM   #2
drewdogg
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If you're looking to use an 05 USDM sti harness for a EJ207 swap, I'd say you're better off using a USDM WRX harness and adding wires for the AVCS. If you had to use the sti harness, I would say most things would work fine, you would have to retune but I'm sure the ECU could do the job. The engine harness would mostly work, use the sti MAF (dunno if they're different but that might make retuning with the sti ecu easier), the 2.0 would be top feed injectors. I can't think of much else different. The 05 ECU would have an immobilizer, so it would be best to have the ECU, steering rack with ignition and key from the same STi. If you got an EJ207 with dual avcs that would be a whole other issue which involves modifying the cams and their timing or swapping the exh cams and gears.

If you want to swap an EJ207 into a US 05 STi.... why?

Last edited by drewdogg; 06-25-2018 at 01:31 AM.
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Old 06-25-2018, 07:03 AM   #3
Kampfzentrum
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Mucho thanks on the reply.

Yeah, I've kinda gave up on the EJ207, I've gotten a bunch of feedback on compatibility that made my head spin. I've got a guy up around my area that tried the same swap with the same hardware ('05 harness to EJ207) and after a year he threw in the towel. With hearing a number of things, I decided to stay with the EJ257; the ease of accessibility is what made me want to go JDM. Having to parts chase an entire long block with accessories can be a hassle.

But since I got your attention: With my '05 harness, is the ECU going to have issues starting if I don't have a matching speedo? What about ABS and airbag delete? I've done the majority of my Subaru work on a '04 NA and that had no issues doing what I want to it, but I also did a 2008 WRX swap into a 2010 NA Impreza and that was a pain, the immobilizer prevented anything from working correctly. Will I have those same issues with the '05? I'm wondering if this harness was a bad buy (I got it cheap so no big loss).
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Old 06-25-2018, 11:58 AM   #4
Titter
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EJ207 Spec C 4EAT

Default 2005 USDM STi ECU/Harness to V8 EJ207 - Potential Issues HELP!

Ej207 in to 32bit Subaru

It's way easier than you would think. Here are the important details.

-EJ255/257 intake cams. Do not use the 255/257 AVCS cam gears, use the 207 gears as they are the ones that will allow you to go 40į of advance. The usdm AVCS cam gears are mechanically limited to 30į.

Use the ej257 cam sensors. You will have to open up the driver side hole 3mm towards the firewall in order to get the sensor right over the cam pick up. Before you install your sensors remove the metal sleeve on the sensor, you might have to open up the bolt holes in order to move the sensor towards the cam pick-up. I replaced the o-rings with thicker ones and a bit or rtv.

You need to use the dbw throttle body on the dbc long runner manifold. I used a KS tech adapter. For this you will have to bore out the mounting holes on the dbw throttle body. The hardware is thicker. A vice and a drill made quick work of it. Don't forget you need a gasket forf both types of throttle bodys, one against the dbc manifold and one on the dbw tb.

You will need to use the dbw ej255/257 engine harness because of the dbw connection at the throttle body.

You will need to swap the injector connectors from the 207 to the dbw engine harness.

Next swap the AVCS solenoid connector from the jdm harness on to the US engine harness.

And that is it! Next plug everything in and flash your 32bit ecu with a map for an ej207and start it up!!



*this is copy/pasted from my notes. itís someone i know that has done this and wrote the write-up. thatís why it is written in the 1st person. i myself have not done this swap.*
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Old 06-28-2018, 10:07 AM   #5
drewdogg
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Titter - nice chunk of consolidated info!

Kamp - I believe the issues with the 08+ swap you did could have been CAN bus related. The 05 harness won't have problems with anything but the ignition key matching the ECU. You can, however, use an 04 STi ECU which does not have an immobilizer with your harness. I think there's pins you have to move around but it will work. There's a bunch of info around on it.
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Old 07-04-2018, 01:07 PM   #6
Kampfzentrum
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Quote:
Originally Posted by drewdogg View Post
Kamp - I believe the issues with the 08+ swap you did could have been CAN bus related. The 05 harness won't have problems with anything but the ignition key matching the ECU. You can, however, use an 04 STi ECU which does not have an immobilizer with your harness. I think there's pins you have to move around but it will work. There's a bunch of info around on it.
Yeah, I have to agree with you, the CAN bus was the issue. But I guess my - limited - knowledge lumps the two together. So with the 05, which has an immobilizer, what issues will come with it? I have a key to the original ignition/ECU. So should an airbag or ABS delete throw it into a lockdown state? I guess I am curious what the immobilizer does.
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Old 07-06-2018, 04:35 AM   #7
drewdogg
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The immobilizer reads the ignition key code which is programmed to the ECU. If the wrong key is used, it won't start - that's it. So airbag or ABS delete won't do anything to affect the engine running.
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Old 07-07-2018, 10:40 AM   #8
ZeroTherapy
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I don't understand what's happening!

Kampfzentrum ur wrx ECU harness have 3 connectors ? and JDM engine have one engine harness connector ?
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