Education Needed - EJ22 ECU Computer Modules

[BirdMobile]

Greets!

I need an educumacation in EJ22 ECU computer modules, specifically those units found in Legacy models of around 1990-1996.

 

This is what I know (not much):

 

Pre 1995, the module is a 4 connector ODB1 (whatever that means) module located behind the instrument panel on the left drivers side if the car.

 

Post 1995, the module is a 1 connector OBD2 (whatever that means) module located under the passenger floorboard in a sealed metal compartment. The connector has a rotating plastic latch in the center that locks the wirimg harmess connector to the ECU.

 

I've read various posts about jumpering wires to tell the ECU whether the transmission is automagic or menial, telling the ECU whether EGR is present or not, etc. I don't pretend to know what all this means - I'm just soaking it in for now and waiting till all the info "clicks" and I understand the setup,

 

I have a heavy background in all things electronic, I've done a lot of microprocessor based hardware and software design, so please don't be afraid of overwhelming me with techie details - I love that $#i7... bring it!

 

Please, fellow Subaruists... tell me EVERYTHING you know about these modules, differences, wiring details, modifications, tricks, etc.

 

Thank you!

 

P.S. My intended purpose is an EA82 to EJ22 swap, into a MT5 transmission GL-10 from 1986. However, please don't limit your info to just that narrow application... I want to LEARN about these boxes.

[BirdMobile]

No love for the ECU?

[idosubaru]

auto's usually have EGR - so those two go hand in hand.

yes  there's an identifier pin i believe that tells the ECU if it's an automatic or manual trans.  All ECU's run both auto and manual vehicles.

 

it's just an ECU.  all 1990-1998 EJ22 ECU's can run every 1990-1998 EJ engine (even the EJ25 and EJ18 - that's how simple this set up is), so the differences are menial to most people.  it would be like asking you whether you prefer paper made from XYZ type of wood or ABC type of wood, it doesn't much matter.  even for those of us that do swaps (me), while you like it and that's really cool, in the end it's benign and there's nothing to gain practically speaking. and many Subaru folks are very practical. 

 

presslab is probably one of the more familiar with coding here, though i don't know how much ECU stuff he's done.  he's gotten into the TCU's.

[idosubaru]

Or - to put it another way - many of us don't have the equipment, skill, or time to get into the processing side of the controller software.  But please do recreate that software and free up every ounce of horsepower and gas mileage you can for us!

 

and make me an ECU that can run an automatic without EGR!

[johnceggleston]

typically, the ECU must match the wiring in the car.

but if you are swapping engine, ECU and harness, this less of an issue.

 

my experience begins in 95 and is fairly simple minded.

the pinout changed fairly much between 95 and 96.

i do not know if it changed enough to keep the engine from running.

 

96 - 97 ECUs (and harness) are the same.

98 - 99 ECUs (and harness) are the same.

but all 4 years will swap and run the engine.

you will just get ghost trouble codes for  the ECU harness mis-match.

example: 97 ECU will run a 98 just fine but you will get a trouble code for EVAP FLOW

since they moved the charcoal canister to the rear of the car.

 

i'm not sure about how this will relate to your ''retrofit'' into another car.

 

pre 95 is OBD1, ''On Board Diagnostics 1",

you can read trouble codes by connecting wires under the dash,

or something like that.

the joy here is you can read codes anytime, any where, if you know how.

 

95 and after is OBD2.

OBD2 requires a code reader, and i suspect gives a little more, a very little more, info.

so if you get a code reader it is easier, in my opinion.

but if you are on the road with no reader, you are stuck.

of course almost all parts stores will read codes for free.

i'm not too sure how they will react when you ask them to read the codes in a 67 VW ???

 

so the best advice is to buy an ECU with a matching chassis harness, same year.

intake harness and sensors should match the ECU year as well. fewer headaches.

which year is less important.

 

by the way, there is no EGR on 90 - 94 ej22 engines.

in general, these years have less / fewer emissions crap.

so if you are worried about that, stick with those years.

 

the 93 - -95 ej18, imprezas, did have EGR,

auto and manual trans i think.

 

hth.

Edited September 30, 2014 by johnceggleston

[BirdMobile]

So...

For later OBD2 (1995+) ECU, is there a aay to "trick out" the ECU using jumpers, or feeding it a voltage or pulse train or something to make it ignore EGR? I will NOT be installing an EGR engine into any car of mine...

 

Side question, where do I need to go to find the wiring differences between the 1995 and the later years ECU wiring? My OBD2 ECU came from a 1995 engine, unfortunately.

Edited September 30, 2014 by BirdMobile

[johnceggleston]

 

is there a aay to "trick out" the ECU using jumpers, or feeding it a

voltage or pulse train or something to make it ignore EGR? I will NOT

be installing an EGR engine into any car of mine...

no, there is no way to trick the ECU.

folks have been searching for this since the first ej22 was swapped into an ej25 car that had bad head gaskets back in the 90s.

but unless you are installing into a  car with an auto trans it isn't an issue.

just use a 95 harness from a manual trans car.

ECU is happy with EGR or no EGR.

 

 

 

Side question, where do I need to go to find the wiring differences

between the 1995 and the later years ECU wiring? My OBD2 ECU came from

a 1995 engine, unfortunately.

 

 

best source is to download the FSMs for both years and find the pinout for each ECU.

finding the FSM is pretty easy,

finding the pinout for ECU is more work, but doable.

 

FSM source:   http://legacygt.com/forums/showthread.php/second-gen-factory-service-manuals-literature-186552.html

[idosubaru]

EGR doesn't matter since you're installing this in a manual trans vehicle.

It's only the automatics where EGR is trickier to work around (though there are multiple options)

So this is really easy in your case.  A few approaches are available:

 

1. Use the engine and body side wiring from a manual trans EJ22 without EGR and you're done. Easy. 

 

2.  An EGR engine with all the EGR stuff removed runs and drives just fine - it doesn't matter.  That's how i did mine, no big deal.  You get a check engine light but I just ignore it, in a swap you don't even need to hook up the CEL. LOL

 

3. Or, if you get an EGR equipped engine you can remove the EGR stuff and then simply reroute a hose/leave the EGR connected but not attached to the engine (i think that's how it's done, been awhile) and you're golden.  There's a thread on here how to do that.

 

You have a minimum of three easy solutions that require no ECU trickery.

Edited October 1, 2014 by grossgary