What is this thing on the back of the intake manifold? It's a '95 Legacy wagon with automatic. We're trying to swap in an engine from a '96 Legacy with a manual, and it doesn't have this excrescence on the manifold or the hole in the head for that copper pipe to thread into. We're going to swap the '95 manifold onto the running '96 engine, but there is no way we can install that copper pipe onto the '96 head.

So, what is this, and can the '95 with AT work without it? can we just put a plug in that thing where the copper pipe goes, and live without it?

The thread where I'm documenting the swap is here:

Had to delete the picture there to make room for this one.

This is right along the lines of what I had to do dropping a 2000 Legacy engine into a 2003 Legacy. They made the first two or three years of that era with the EGR but didn’t for the last two. Or the other way around. 
 

On that one, as you should do, keep the original intake. You’ll have to get the drill and tap for that EGR pipe. Don’t drill too deep. Take the other one out and measure that depth and put some tape on your drill bit as a marker. 
 

I think it’s an M22 x 1.5 but double check that. I might have that set still. I had loaned it but I think Jesse gave it back. But for me to find it right now would be tough. Otherwise I’d mail it to you. 
 

I had my daughter get it from Amazon and it was like $16 for the set. Use a smaller pilot drill first. 

Wow! That’s a pain.

So that's for EGR? That means I can just plug the hole and be happy, right? 

Yes.  That's the EGR valve.  You can definitely run without it, and some choose to do so.  Happy would depend on whether you're OK with a permanent check engine light, the emissions laws in your state, and your comfort with increased NOx emissions.

I've left the valve and have tapped into the airbox.  It works as well.

Imdew, sounds like you're just grabbing filtered air from wherever, right?

On 4/27/2025 at 6:06 PM, lmdew said:

I've left the valve and have tapped into the airbox.  It works as well.

You connected your EGR pipe to the airbox? Um.....

And/or try this: 

 

Yes fresh air from the airbox.  I've tapped into the 1" dia hose going to the IAC and also directly into the airbox on cars that do not have the large IAC hose.

20 hours ago, lmdew said:

Yes fresh air from the airbox.  I've tapped into the 1" dia hose going to the IAC and also directly into the airbox on cars that do not have the large IAC hose.

So when the EGR valve opens, the engine revs up?

It's supposed to go to the exhaust...

 

I'm confused

No exhaust to intake.  So just another source of air.  EGR video link below.

Bing Videos

Did hooking that line to the filtered air make the check engine light go out?

Yes as the valve is working as it should.

I do not delete EGR on almost any of my vehicles. But I know they often have a temperature sensor as part of the circuit to verify the systems functionality.

On 5/15/2025 at 11:04 PM, lmdew said:

No exhaust to intake.  So just another source of air.  EGR video link below.

https://www.youtube.com/watch?v=JTCrv8fnZPQ&t=99s

 

Good video, I suggest you watch it. Lots of good information about why it's supposed to be exhaust gasses. It's not "just air".