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95 impreza L 1.8 white
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Discussion Starter · #1 · (Edited)
Hi rs25 community I have been working on reverse engineering the OBD1 subaru ecus for about 2 years now and have come up with a generic editor that allows adjustment of basic functions of almost all jecs based subaru ecus. It uses tunerpro rt v5 with my XDF. You will need a rom adaptor Diagnostics and Datalogging for Subaru SVX
and either a chip burner or eprom emulators I chose the latter www.moates.net (2x ostrich v2.0). My test mule and DD is a 95 impreza L 1.8 that I diy turboed. I am currently running 12 psi with 480cc yellow tops SVX maf and a GT25 turbo. I am sharing because I am hoping to get a knowedge pool going and end up with something open source for our cars like the nissan and honda guys have plus I have been abusing the resorces on this site for some time now and wanted to give back a little. I also posted this in the NA tuning section and realized this area was probably better.
 

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95 impreza L 1.8 white
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Discussion Starter · #2 · (Edited)
eprom adapter for OBD1 jecs ecus

Just trying to make it easier for anyone who wants to persue this so im posting my revised chip adapter board you will need to download expresspcb software http://www.expresspcb.com (I tried to attach it to this post but the file was too big) to finish the adapter you will also need.

Digikey part numbers

qty.1 ED7264-ND
qty.2 296-27984-5-ND
qty.4 478-6008-ND
qty.2 A347-ND

if you go the eprom route you will also need

qty.2 27sf512 flash eproms

and an eprom burner www.moates.net
 

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needs more cowbell
95L, 07 2.5i, R6
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Very nice job, there are TONS of guys/gals who should be reading this. So in theory you could flash the jdm obd1 ecus for example?
 

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95 impreza L 1.8 white
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Discussion Starter · #4 ·
yes the early wrx ecus share many addresses in common with the na ecus (namely the fuel, basic timming, MAF, load multiplyer, injector dead time, and idle speed tables) I have more expanded XDF's for people interested in doing more but I figured this would get people started and if there was alot of intrest then we would expand this thread from there.
 

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Wannabe JDM GF4
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Wow nice, i wanted to do this. Just to mess around and wee what i can do. is it a pain to make your own connector? is it easier to buy one?
 

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95 impreza L 1.8 white
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Discussion Starter · #7 · (Edited)
The eprom adapter or memory adapter must be made to reprogram our ecus (OBD1) if you open up the ecu you will see that most US ecus (the jdm ecus wont always have the socked but will have a spot for it with the holes soldered in you will have to desolder and insert the socket) will have a socket to insert an external chip (14x2 dip socket) the chip that subaru originally intended to use in this socket is hard to come by and requires a really expensive programmer so phil skuse (over at the SVX site) with alittle outside help developed a chip adapter that allows the use of readily available chips, after this adapter is made and installed cut jumper J1 to enable the external rom burn the chips install them in the adapter board and go for a test drive.

these ecus also have the SSM diagnostic port (SSM1) which can be used for data logging and reading the rom image from the ecu (this process can take up to 4hrs and will probably kill your battery unless you put a charger on it) allthough the baud rate and refresh rate is very slow and not extremely usefull unless logging only a couple of data chanels. the SSM port comunicates on a TTL level (0v - +5v) so an adapter will be needed, I use one from www.moates.net originally designed for datalogging hondas There are a couple of data retrieval programs out there for early subarus www.vwrx.com has a freeware version that works pretty good once you have the address file for your particular vehicle. I also made an ADX file for tuner pro that works pretty well. (I only have one for my car right now)

wow this got really long, enough for now.
 

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yep. you heard me.
‘18 E63s AMG wagon & 10 Subarus
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I read all that info on the svx site, sounds pretty promising. Is there no way to reflash the ECU using the select monitor plug and the appropriate computer adapter? Or better yet just modify a few of the data points in the ECU's programming via pc-> Select monitor plug?
 

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95 impreza L 1.8 white
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Discussion Starter · #9 · (Edited)
In the info that I have read It makes it seem possible that you can change the data in the ecu but that its temporary (if the key turns off back to stock). But havent actually tried it my self because the comunication is extremely slow and you have to shut the car off every time you want to make a change.(its not realtime) with the adapter board and the ostrich v2's you can make realtime changes and have realtime trace. basically oem ECU performing like a standalone.
 

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95 impreza L 1.8 white
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Discussion Starter · #11 · (Edited)
the original com adaptor that I made was based on the one on the SVX site and worked very well and infact is the only adaptor that I have that can read the rom image from the ecu.The rensu software http://www.rensu.net doesnt agree with the usb to ttl adaptor that I bought from moates but works fine with tuner pro.
 

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95 impreza L 1.8 white
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Discussion Starter · #12 ·
Just to make myself clear. Im not claiming to be the person that started all of this, infact I think that there is a thread on here from years ago that started getting into all of this. Im only working on the 93-95 impreza ecu at the moment but have learned alittle about other platforms along the way. Large amounts of my information came from www.alcyone.org.uk/ssm and in my opinion Paul skuse is the man with subaru ecus. I just wanted to give back alittle (with the generic XDF) and collaborate with some like minded people. For all I know there is already somthing out for the 93-95 NA imprezas but I havnt found it yet.
again just trying to make myself clear.
 

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95 impreza L 1.8 white
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Discussion Starter · #14 ·
I made the original. The serial port based one with the signal conditioner. I used to have a laptop with a real serial port. Ive tried tons of usb to serial adaptors since with that com adapter and none of them worked, so I adapted a usb to ttl (purchased from moates.net )that I had from my honda tuning days and it works fine with my tunerpro dataloging. When I need to pull a rom from an ecu nowadays I just hook up the ecu to my benchtop power supply and use my desktop pc with the serial adapter.
 

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Group 2 Impreza Rally car
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this is very interesting. I have been playing around with MS for a while but retaining the stock ecu has its advantages. I'm surprised the alcyone guys haven't updated their pcb to accept the newer (and more available) PLCC chip like the ECUtune guy has (apparently he plans to start selling blank adapter boards).
 

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Meany Head
2000 RSC
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... that allows adjustment of basic functions of almost all jecs based subaru ecus.
Wow!! You have my attention!!
I don't suppose there is enough overlap between OBD1 & OBD2 JECS ECUs that you think you'll be looking into those too? (fingers crossed) Or are you going to stay on the OBD1 ecus?

<-- Also an ECU guy, but the software side. I'm the creator of ECUTracker
 

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1995 WRX 2015 F150
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FWIW I can pull the ROM off the 93-96 JDM turbo ECUs with a FTDI FT232RL usb to TTL cable. It works fine, the cable has the converter chip embedded in it. It does take a long time as noted and you need to leave the car on a charger. I can read and modify the ROM with romraider. That works fine as well. Somebody did the defs for these in romraider a few years ago. If I bought a chip burner, I'd be able to tune these ECUS, but I haven't been motivated enough to do that yet. The chip I got from Rob runs really well and I haven't had a need to change things.
 

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1994 WRX Type RA
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I also went this route when tuning my early WRX. I used Phil's plans from Alcyone Limited, and it works perfect.

Since expressPCB prints 3 circuit boards, I have 2 spares that should be complete (just add eproms and go). I figured I might as well build all 3 rather than have 2 blank circuit boards kicking around.
 

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How much did you guys pay for chip burners? I understand the burner that can do the original fujitsu chip is expensive? How much is a burner that can do the chips the daughter board takes?
 

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95 impreza L 1.8 white
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Discussion Starter · #20 ·
I have two chip burners one I bought from batronics 3-4 years ago for $400 it can burn all kinds of different chips with a adaptersocket and the other I bought from moates about 5 years ago for @100$ after my zietronics? (I think that's the name) burner died after about 11 years. I've been tuning hondas and nissans since @1999 and figured might as well go for Subaru too. I'm also working on the early Mazda ecus93-95 if anyone cares.
 
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