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'97 Outback...got a great deal on a '96 2.2 to replace the now deceased 2.5. Problem is, 2.2 is out of a MT car, so no EGR. I know this has come up before, but searched and found nadda. Anyone know how to keep the CEL light from coming on...bypassing the EGR? Should be able to put a resistor in somewhere to fool the computer...anyone know how this can be done? :confused:

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That's what I've always wondered and I've brought it up before. You can find the old threads and see what folks say, but I don't think it was anything definitive. It may even be that the ECU's aren't actually different.

 

I've always thought that messing with the EGR is the wrong way, why not make it think it's one of the "non-EGR" vehicles.

 

But, I've asked before and it doesn't seem like anyone knows the magic formula.

 

The ECU issue is that almost all non-EGR 1995+ ECU's are manual transmissions. So if you have a manual trans that might work. If you have an auto you're hosed. Although I did own a 1997/8 Impreza OBS EJ22 without EGR that was an automatic. DANG IT I wish I would have known back then about this and I would have taken the ECU. The intake manifold (non-EGR) is the one currently in my Legacy LSi, so i'm absolutely positive it was a non-EGR automatic. Good luck ever seeing one of those again.

Edited by grossgary
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It is a manual trans car, but the donor vehicle is long gone. So what year ECU should I look for...maybe a '95 legacy with MT?

 

Cool, I would try exactly that.

 

But, it might not be as simple as swapping ECU's. Often the ECU's can run either car, they are "looking" for inputs and pins that tell them what the car is.

 

That's why you can interchange ECU's between auto and manual vehicles - the ECU 'knows' what it is and can run either by identifying it.

 

Same thing could happen here - you install a "nonEGR" (so you think) ECU into your car, but then it "sees" that yours is an EGR equipped vehicle so it still throws the code.

 

That being said, it's worth a shot since the ECU is so easy to replace. Any 1995-1998 EJ22 ECU would be fine. Just make absolutely sure it doesn't have EGR.

 

A 1995 Manual should be a sure bet, assuming the ECU's are interchangeable. For some reason I feel like I got a 95 ECU and it was different plugs, but I might be mistaken. Someone will pipe up an verify that.

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I have a '96 ej22 in my GL. It was throwing an egr code before I grounded the pin that told the ecu that it was supposed to be for a manual tranny. Afterwards, no code. So for the 96's the ecu's should be the same for manual and auto transmissions. You just have to let it know which one you have.

 

As far as 97's go, I have no idea.

 

-Doug

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For the 96 ecu the AT/MT identification is pin 81. On the 96 wiring harness it is a black wire with a white stripe. It needs to be grounded to tell the ecu that it is a manual.

 

Before I did this it had the egr code and a auto trans diagnostic code (1702 I think) because it was looking for the auto tranny that wasn't there. It also cured a high cold start idle (2500 rpm) and made that function normally as well.

 

Hopefully some of this is relevant to his '97 model.

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Awesome. An easy fix like this is what I was hoping for. Pulled the engine last nite, looks like it'll need a clutch too, so it'll be a week or two before I have the parts and time to reassemble. Thanks for all the help, I'll follow up once everything is up and running...

 

...edit...wait a sec...this is a manual trans car...engine is also from a manual trans car...don't see how grounding the ECU is gonna help in this case...since this manual trans car is supposed to have an EGR...

Edited by outbackusjunkus
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  • 1 month later...
  • 2 months later...
i have the entire car, so should i swap ECU or not.
you can but that won't get rid of your CEL's. and then ground the pin and you're still going to have issues because you have an automatic transmission. that further confuses it.

 

unless you swap the manual trans in then of course you're fine.

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I did a quick review of the wiring schematic looking for diffs between a 1995 EJ22 ecu and EJ25 ecu hookups. I saw that there were several diffs that would make a big difference and explained the fact that, when i installed my 95 ecu in the 97 outback with 1995 EJ22 installed, I got a nostart condition.

 

So.....don't think that installing the ej22 is going to work with you folks either.

 

I've also played with introducing a signal back to the 97 ecu by introducing 12 volts with a resistor to knock it down to about 5. Still got the cel. In reading more about the issue, the computer is also looking at sensors that would indicate that the egr is allowing hot exhaust gases back up into the intake (via the tube that WAS installed on the ej25 head/intake manifold). If it doesn't sense that the exhaust is being allowed back up into the intake, it throws a cel. I'm still not certain whether there is a negative affect on how the vehicle runs tho. My ej22 runs pretty well at idle. But when cold i get a bucking unless i raise the revs when in lower gears. I also don't get the gas economy that I was hoping for.

I'm leaning toward drilling/tapping the rear side of the ej22 head to allow installation of the egr tube.

 

ps: if anyone is interested in taking a look at the wiring diagrams i'm referencing, have a go...

http://www.weidefamily.net/vanagon/Pending_Content/Engine_Conversion/Reference/WiringDiagrams/

 

brent

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Is it not just an EGR temp sensor? There should be a +5v signal from the ECU going to some kind of thermistor that tells the ECU there is exhaust gas flow through the EGR. Take that signal, run it through a relay controlled by the signal to the EGR solenoid, then through two 5 watt resistors that simulate the voltage drop in the 5v line both with/without EGR flow (so the ECU see's the temp change when it shuts off the EGR vacuum supply).

 

The ECU isn't that smart - it's looking for a temp change in the EGR passage when it opens the EGR solenoid. Find out the proper resistances that the thermistor generate's at typical EGR temps and give the ECU the signal it wants.

 

GD

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i installed my 95 ecu in the 97 outback with 1995 EJ22 installed, I got a nostart condition.
that would only be for 95 model years - all EJ25 DOCH vehicles will run just fine with an EJ22 ECU from 1996-1998, completely interchangeable. Of course all the EGR and auto/manual items still apply.
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FWIW...this car is now up and running with the '96 2.2 (w/o egr). the car ('97 OBW) is throwing the egr code but runs fine. I've done some more research, found a guy who swapped in another non-egr computer but it still threw the code...he ended up splicing the sensor into his wiring harness (just before the engine, as the new intake does not have the wiring for egr). its the two wire sensor that's on the intake of the egr motor, next to the egr valve. that cured his problem. i'm planning on doing the same...maybe this weekend when i pull the engine back out to fix leaky head gaskets (i know...2.2's aren't supposed to do that...but my 2nd used 2.2 in a row with bad head gaskets). I'll stop back with the result.

Edited by outbackusjunkus
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FWIW...this car is now up and running with the '96 2.2 (w/o egr). the car ('97 OBW) is throwing the egr code but runs fine. I've done some more research, found a guy who swapped in another non-egr computer but it still threw the code...he ended up splicing the sensor into his wiring harness (just before the engine, as the new intake does not have the wiring for egr). its the two wire sensor that's on the intake of the egr motor, next to the egr valve. that cured his problem. i'm planning on doing the same...maybe this weekend when i pull the engine back out to fix leaky head gaskets (i know...2.2's aren't supposed to do that...but my 2nd used 2.2 in a row with bad head gaskets). I'll stop back with the result.

 

to make this process easier, should you use the wiring harness from the egr engine and then connect the sensor, with the egr car's computer of course.

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  • 2 weeks later...
to make this process easier, should you use the wiring harness from the egr engine and then connect the sensor, with the egr car's computer of course.

 

Thought about that, but went the easy way. Spliced in that two wire senser off the 2.5 EGR into the wiring just before the engine and bingo...no more light. Its been a couple days now and the light has stayed gone, so looks like problem solved. Yay...:banana:

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Thought about that, but went the easy way. Spliced in that two wire senser off the 2.5 EGR into the wiring just before the engine and bingo...no more light. Its been a couple days now and the light has stayed gone, so looks like problem solved. Yay...:banana:

 

which wires on the main harness do you use to splice it in?? colors, etc... or a pic would be even better :)

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