Subaru STI M800 2008-2015 on a 2004 engine

[Fercomp]

Hi there,

Have an STI M800 from a 2009 that I want to swtich to a 2004 engine.

Currently the 2004 is running a 2010 N14 GEMS ECU that had a different firmware installed to run the 04 engine.

Is this possible with the Motec unit as well?

Thanks.

[mrsaturn7085]

Please clarify the origin market of the engines - the USDM 04-06 single AVCS EJ257 is very similar to the 08+ USDM EJ255 and EJ257 and the WRX9-10 board can be utilized fairly easily with a patch loom.

I guess the easiest way to ask this is:

Year/make/model/market of the chassis & wiring?
Year, market, and engine code of the engine?

[Fercomp]

My apologies. I thought I had typed that but forgot.

Yes both engines are USDM EJ257. One is 2004 and the other is 2009.

Thanks.

[mrsaturn7085]

The WRX9-10 board can easily control that motor and as an added benefit, you'll regain 2x inputs and 2x outputs minimum from the single AVCS system.

Which chassis/wiring are you using with this? The 2009 will need minor changes made at the engine side of the loom, while the 2004 will need a patch loom manufactured for the ECU-side.

[Fercomp]

The chassis is a GC8 rallycar with the 2004 STI harness. I have read on NASIOC that there's schematics available for this.

[mrsaturn7085]

While I am sure there are more than 3 people to have done this, there are only three I know of on NASIOC - myself, a user by the name of 'alcoolaid', and a user by the name of 'berdugo' (who had some issues but eventually got it working).

The 2004 USDM STI had a 3-wire alternator while the 05-06 had a 2-wire deal. Beyond that, I'd have to double-check the wiring differences.

The patch loom took me about 30 days of reviewing/revising wiring lists, comparing the 2008 WRX/STI, 2006 WRX, and 2006 STI. The loom was manufactured by Boomslang and cost approximately 500 USD. I actually am planning on manufacturing a 'Mk.II' revision to the patch loom for some additional needs I have, and might be willing to part with the one I'm currently using - PM me if interested and we can get in-touch.

-Steve