How does a non EGR engine, intake manifold, and ECU give EGR code?

[idosubaru]

I installed in a 96 Legacy an intake manifold, engine, and ECU from non-EGR automatic EJ vehicles. So the only thing left from the EGR set up is the body harness - right? I cut the EGR wire at the ECU - pin 71 Black/Pink.

 

I still get the EGR code.

 

Why is the computer looking for an EGR when it comes from a non-EGR engine and has a non-EGR engine/intake manifold?

 

So it has to be some other wire/circuit or sensor or the feedback from the TCU (Unlikely)?

 

If they make a non-EGR automatic - why does Subaru not have that in the FSM's?

[WoodsWagon]

There is no non-egr automatic OBDII. Sorry, but whoever had swapped the non-egr engine into the 96 automatic lived with the egr code too. If the computer is put in an automatic car, it looks for EGR.

[86subaru]

my 2000 a/t 2.5 has no egr, no engine code,engine never been swapped, ob 2

Edited May 9, 2010 by 86subaru

[OB99W]

I installed in a 96 Legacy an intake manifold, engine, and ECU from non-EGR automatic EJ vehicles. So the only thing left from the EGR set up is the body harness - right? I cut the EGR wire at the ECU - pin 71 Black/Pink.

Gary, disconnecting ECU pin 71 shouldn't change anything, once there's no EGR solenoid. I assume there's also no wiring/connector for one in the engine harness at this point -- is that the case?

 

 

I still get the EGR code. [...]

There are two primary EGR codes (and some less-typical ones). P0400 indicates detection of a flow problem. P0403 is triggered by a solenoid circuit fault. Which code are you getting?

[idosubaru]

There is no non-egr automatic OBDII.

They are very rare, but they're out there. I'm equally confused about why/how Subaru did it.

 

I assume there's also no wiring/connector for one in the engine harness at this point -- is that the case?

It came from a non-EGR automatic. I never looked closely but I don't recall seeing a connector when I did the swap, I assumed it didn't have one.

 

Gary, disconnecting ECU pin 71 shouldn't change anything, once there's no EGR solenoid.

That makes sense, no sensor = ECu doesn't see anything? I just can't figure out how these ECU's "know" or "don't know" it's a non-EGR auto.

 

Which code are you getting?

I had both 0400 and 0403 yesterday and no others, been driving the car like this for a couple years. I cut the wire and drove the car 35 miles and now have only 0403. So either I haven't driven enough and 0400 comes back or cutting the wire got rid of one code (doubtful)? Edited May 9, 2010 by grossgary

[OB99W]

I had both 0400 and 0403 yesterday and no others, been driving the car like this for a couple years. I cut the wire and drove the car 35 miles and now have only 0403. So either I haven't driven enough and 0400 comes back or cutting the wire got rid of one code (doubtful)?

Although you didn't say so, I assume that what you did was cut the wire and reset the ECU, then waited to see what codes would/wouldn't return. (Correct me if I got that wrong, please.) If so, P0403 would likely return rapidly because the ECU can immediately detect the lack of EGR solenoid continuity. (One end of the solenoid goes to 12 volts, the other to ECU pin 71. So the ECU should see pin 71 get pulled up whenever it isn't trying to energize the solenoid by pulling that pin to ground. If pin 71 doesn't go high, that should cause P0403 to be triggered.)

 

On the other hand, EGR flow problems are detected by running conditions. That means that the I/M monitors have to complete, including a couple of drive cycles, before P0400 will trigger a CEL (although if scanned it might show as pending).

 

On MT cars, which typically don't have EGR, pin 81 is grounded. You can't really do that to resolve the lack-of-EGR problem with an AT, because there are other differences.

 

Although I've never done what I'm about to mention, Gary, you seem to be willing to experiment. I wonder what would happen if pin 71 got pulled up to 12 volts via a resistor. A 1,000 ohm (1 kohm) 1/2 watt resistor connected from a switched (not always hot) 12 volt source to pin 71 might fool the ECU, at least as far as whether there's an EGR solenoid. That could potentially eliminate P0403 at least.

 

DISCLAIMER: Anyone (this means Gary and/or any other) who tries what I mentioned in the paragraph above does so at his/her own peril! (As I said, I've never tried it myself, and although offhand it would appear to not be problematical, there might be unforseen consequences.) You've been warned.

[idosubaru]

Disclaimer rightly heard, I am perfectly fine ruining my car. Thanks for the help OBW, I think I'm probably hosed if you don't know, thanks for helping.

 

Others have put a resistor in for the EGR and it didn't work, I believe they said because it looks for more than resistance. But it shouldn't need fooling - the ECU just needs to think it's a non-EGR automatic which Subaru has made in rare cases. So how to make the ECU *think* it's a non-EGR?

 

The engine, intake, and ECU are from non-EGR vehicles.

 

The 5 dollar question is how does Subaru make a non-EGR automatic? No mention in any of the FSM's I have.

 

MAF? TCU? Body wiring? Am I missing a solenoid somewhere? Is the non-EGR solenoid different?

 

I wish I would have had Larry (lmdew) cut off the connector to the ECU of the non-EGR auto so I could have compared the wires to mine. I'd love to find a car like that again to play with, I had one about 5 years ago.

[WoodsWagon]

The 5 dollar question is how does Subaru make a non-EGR automatic? No mention in any of the FSM's I have.

 

That's more of a $50 question. That would solve a lot of the issues with finding 2.2l to put in place of 2.5l potentially. If answered, then you could use any 2.2l from 90-98.

[idosubaru]

That's more of a $50 question.

yah, no doubt i'd give more than to figure it out at this point. !

[OB99W]

[...] Thanks for the help OBW, I think I'm probably hosed if you don't know, thanks for helping.

You're welcome, and thanks for the vote of confidence (although I'm not sure it's totally merited. )

 

 

Others have put a resistor in for the EGR and it didn't work, I believe they said because it looks for more than resistance. But it shouldn't need fooling - the ECU just needs to think it's a non-EGR automatic which Subaru has made in rare cases. So how to make the ECU *think* it's a non-EGR? [...]

On a swap where the original had EGR and the replacement doesn't, I can see why just faking the solenoid valve isn't going to do the trick -- the ECU might be satisfied electrically, but when it does a flow test, it's not, and triggers a P0400.

 

However, in situations like yours I've heard of people who just stuck an EGR solenoid valve in circuit (again, one lead to switched 12 volts, other to pin 71 of ECU), and got neither P0400 or P0403 again. (Don't ask me why, I don't know. )

 

If you have a spare EGR solenoid valve around and feel like experimenting, why not wire one in? If anything good comes of it, humor me and try the resistor I mentioned above if you're okay with that.

[hankosolder2]

I tend to think that the 1K ohm pull up resistor will be too high. Measure the resistance of an EGR solenoid and use the closest standard value resistor. Depends on what the computer is monitoring. It may measure the current through the solenoid rather than having a simple high-impedence logic pull-up type input.

 

However, I'm pretty sure that won't fix your problem, as I doubt a non-EGR automatic car has a "fakeout" resistor. There'd be no reason for Subaru to include an extra part as opposed to simply telling the ECM not to check that input via either a software difference or grounding/jumpering some input to the ECM.

 

Has anyone tried installing a complete EGR system EXCEPT for the pipe to the exhaust feed in the head? The computer has to be looking for either a change in mixture (via the O2 sensor) to verify EGR flow or a change in the MAP sensor. (Vacuum will drop when the EGR valve is open.) If you allowed the EGR valve to suck a bit of air when activated, I think you might be able to fool the computer. Might have to fiddle with the BPT (as there will be no back pressure to help modulate the EGR flow) and you might have to put an orifice on the input of the EGR valve to regulate the size of the vacuum leak...

 

 

Nathan

[idosubaru]

Yes OBW i'm willing to experiment and I have plenty of engines/parts to play with.

 

There has to be a simple way since there are non-EGR automatics.

 

Odd thing - is this ECU came from a non-EGR auto and triggered EGR codes, so apparently the ECU's are interchangeable.

[OB99W]

I tend to think that the 1K ohm pull up resistor will be too high. Measure the resistance of an EGR solenoid and use the closest standard value resistor. Depends on what the computer is monitoring. It may measure the current through the solenoid rather than having a simple high-impedence logic pull-up type input.

The EGR solenoids typically measure about 35 ohms. With a 14 volt supply (engine running), that would dissipate over 5 watts. That's why I suggested trying a spare solenoid first, and if that "worked", next seeing what a 1 Kohm 1/2 watt resistor would do (since it would dissipate less than 1/4 watt). If anyone is going to try a 35 ohm (or so) resistor, be sure you use one that's rated to dissipate the power, and locate it away from anything that won't like the heat given off.

 

 

However, I'm pretty sure that won't fix your problem, as I doubt a non-EGR automatic car has a "fakeout" resistor. There'd be no reason for Subaru to include an extra part as opposed to simply telling the ECM not to check that input via either a software difference or grounding/jumpering some input to the ECM.

Nathan, I'm in no way suggesting that what you've predicted won't be the outcome, nor that your supposition of Subaru's design is inaccurate. However, squelching "research" doesn't seem productive to me.

 

As I said previously, I don't know some of the details of the EGR/non-EGR arrangements, and apparently neither do any of the other forum members (or they aren't willing to speak up). Gary's situation is somewhat different than many other swaps, since he is using parts that apparently came from non-EGR AT cars. That some people have successfully used just a solenoid to get around the problem is "hearsay", as I already freely admitted. The thing is, Gary is willing to try something, and any feedback is useful, even if it just confirms that it doesn't do the trick.

[WoodsWagon]

Has anyone tried installing a complete EGR system EXCEPT for the pipe to the exhaust feed in the head? The computer has to be looking for either a change in mixture (via the O2 sensor) to verify EGR flow or a change in the MAP sensor. (Vacuum will drop when the EGR valve is open.) If you allowed the EGR valve to suck a bit of air when activated, I think you might be able to fool the computer. Might have to fiddle with the BPT (as there will be no back pressure to help modulate the EGR flow) and you might have to put an orifice on the input of the EGR valve to regulate the size of the vacuum leak...

Nathan

 

The whole point of the EGR system is to introduce an inert gas into the intake to take up volume in the combustion chamber without adding to the chemical reaction of combustion. That lowers combustion temps, which reduces NOx. It doesn't change the fuel/air mixture to have exhaust gas getting pulled into the intake. Having a vacuum leak to outside air would, as the excess unmetered air would throw the mixture lean.

[NorthCoast]

Hate to necro an old thread but after searching and searching I haven't seen a viable solution for this problem.  I'm getting the same P0403 on a car that doesn't have an EGR nor has it ever.

[Fairtax4me]

What year is the car? How long have you been getting the code?

Are you the original owner, and know with 100% certainty that the engine and/or computer have never been swapped?

[NorthCoast]

97 OBS. Just recently started getting the code. Not the original owner (4th I think) and I'm 100% sure the engine HAS been swapped at least 4 times (twice by me).  No idea on the ECU.

[johnceggleston]

year?

model?

engine?

trans?

miles?

color?

other info?

 

read the ID tag on the driver side strut tower under the hood,

and give us the trans id number.

Edited July 2, 2015 by johnceggleston

[NorthCoast]

1997 Impreza Outback Sport

 

EJ25D with EJ22E heads and intake

 

Original trans code: TZ102ZA5AA

Current trans code: TZ102Z2CBA

 

Mileage and color really don't matter.  Current ECU is marked "3W". No idea if that is the stock one but I'm pretty sure it is.

[Fairtax4me]

There's a 10 or 12 digit Subaru part number on the ECU that you can try looking for on opposedforces parts site.

 

How recently? Weeks? days?

And how long have you owned the car?

[NorthCoast]

A couple of weeks. Got the CEL right before I went in for emissions testing.  I've had the car for a few years now. 

[idosubaru]

automatic or manual?

 

can you easily swap in another ECU and see what happens?

 

does it currently have a non-EGR engine and non-EGR intake manifold?

or are they EGR deleted engine and manifold?

 

if it wasn't doing it for years and then all of a sudden started giving you this code - there's more to this than an engine swap/difference.

 

more work than you want, but a work around is to install an EGR equipped manifold, remove the EGR and then simply reroute vaccum lines for the solenoid to make the ECU happy - there's a thread on here about it.

or dig into the wiring and see what the ECU wants to see regarding the EGR solenoid that trips this code - and splice it in place with vacuum tubes strategcially placed as mentioned.

[NorthCoast]

I got the same code with another ECU.  It currently has and has always had a non-EGR engine and intake.

[johnceggleston]

that is an EGR car.

with the exception of the few GG has found / seen,

ALL ej22 cars 95 - 98 with the auto trans are EGR.

 

if you swap in an EGR intake manifold,

from an ej22 car 95 - 97, with EGR, usually an auto trans car,

and then do the EGR ''work around'' 

your code will go away.

 

Using a NON-EGR engine in Subaru with EGR - Submit a Tip or Mod to the USRM - Ultimate Subaru Message Board

 

and since you are the 4th owner,

and there have been 4 engines in this car,

there is no way you can be sure it has never had EGR.

it was EGR from the factory.

 

now about the trans,
 

 

Original trans code: TZ102ZA5AA

Current trans code: TZ102Z2CBA

 

the original trans had a 4.11 final drive ratio.

the current trans has a 4.44 final drive ratio.

i sure hope the rear diff matches the trans.

 

this car has been around the block a time or two.

 

you can ''fix'' the EGR as i mentioned,

but unless the code will keep you from passsing an inspection,

or keep you from legally driving it ,

i would just live with it .

Edited July 2, 2015 by johnceggleston

[NorthCoast]

Not a newb John, of course the rear diff matches the trans.  The code is the only thing keeping me from getting new tabs.  I was looking to see if anyone had come up with a legitimate way to fix the code either by grounding pin 81 or by using a resistor. I really don't want to try and find an EGR manifold especially when this has never been an issue in the past.