Not to beat a dead horse... (EGR idea?)

bewestro · **Posted:** Sun Sep 28, 2008 9:05 pm

I've been reading lots of posts about the EGR issue and possible solutions, and had an idea I haven't seen discussed yet (please feel free to cyber-smack me if this has been covered and I missed it).

As I understand it, when the computer decides to introduce exhaust air, it fires the EGR valve and the FCV: the EGR valve to access the exhaust gas, and the FCV to sort of "force" the engine to suck some of that instead of all fresh air. The MAF sensor makes sure there is a corresponding drop in fresh air flow at that moment. If you just block off the EGR valve and take the butterfly out of the FCV without any special computer tune, it notices something isn't adding up. Then it gets angry and glowers at you with it's little amber light.

SO... could you block off the exhaust to the EGR valve, but also run a line to it that feeds it fresh air instead? Either from a second air box mounted...somewhere... or drill into the back of the existing air box (ahead of the MAF) and run a line from that? Leave all the electronics and components as they are. That way, when the EGR & FCV fire, it still pulls fresh air. Just from a different place. The MAF should still see a corresponding drop in flow where it is, and not complain. And I'm thinking that if the EGR valve isn't operating in that hot, sooty environment anymore, that it might even last longer. Also, your shutdowns should remain smooth because the EGR valve will block off the fresh air, and the FCV will function as intended.

I'm not sure this is possible, and I might not have any idea what I'm talking about, so please help me learn. Thanks!
--Ben

Goglio704 · **Posted:** Sun Sep 28, 2008 9:54 pm

That general idea has been discussed before - back before the ORM or the SEGR. I don't think anybody ever shot holes in it or tried it out. Let us know how it works.

CATCRD · **Posted:** Sun Sep 28, 2008 10:03 pm

Usually there is positive pressure in the exhaust manifold that helps push the EG into the intake. In your example you would lose boost pressure out your second airbox. Basically the air would flow in the opposite direction as you are wanting it to.

Goglio704 · **Posted:** Sun Sep 28, 2008 10:07 pm

The connection to the exhaust manifold would be - gone. A check valve would be needed to prevent loss of boost, and you would never get correct flow through the second filter unless the closed butterfly actually produced vacuum in the intake. Don't think I like that part. I think electronics do offer a much more elegant solution, but I think the OP's idea could work - and/or be a lot of work. :wink:

nursecosmo · **Posted:** Sun Sep 28, 2008 10:39 pm

Even when the FCV is semi closed as in when the EGR is open, there is still a significant amount of boost (except at idle and even then there is some) which is normally overcome with the exhaust pressure so that the air flow does not go backward into the exhaust. If you did not have that back pressure on the line going through the EGR tube, the charge air would go right back down to wherever you were pulling it from.

BlackLibertyCRD · **Posted:** Mon Sep 29, 2008 12:19 am

What I understand about the ORM or the SEGR the FCV is also disabled except when you shut off the engine when it shuts for a moment to aid in quicker shut down. I'm using the ORM and like the fact that the FCV is not choking the engine while I'm accelerating down the road.

gmctd · **Posted:** Mon Sep 29, 2008 1:13 am

The key is Exhaust Gas Pressure, which is at least equal to Boost pressure, often greater than Boost pressure - so, no, the idea is not workable

ATXKJ · **Posted:** Mon Sep 29, 2008 11:07 am

Actually - it's been done.
someone named Farmboss said he blocked the EGR and routed intake air to compensate. However - that leaves the FCV functioning - and since it chokes intake flow - it's not as good as the SEGR.

He never posted any pictures or anything more than a general description - and then got in an argument with the moderators and hasn't been heard from since. Most of his posts ended up deleted including the general description of his mod.

gmctd · **Posted:** Mon Sep 29, 2008 12:52 pm

He may have plumbed it, but it is not workable, as intake pressure is either Baro at zero Boost, or Baro + Boost at Boost event - EGP is always higher than Baro and Boost pressure - pressure equalizes to any lower pressure, not vice versa - I did not indicate the idea is not plumbable, but that it is not functional, as MAF output is Barometric\volume referenced against higher pressure of EGP reducing that volume

tulsa · **Posted:** Mon Sep 29, 2008 12:54 pm

What if:
you added a solenoid operated path from the filtered side of the airbox around the MAF, plugged off the source of the exhaust gas to the EGR, fed the EGR with intercooled compressed air from the turbo and removed the butterfly from the FCV? Would that be the rough equivalent of the SEGR, just a lot more work?

Lewis

gmctd · **Posted:** Mon Sep 29, 2008 12:59 pm

Boost pressure (MAP) plumbed to the exhaust inlet side of the EGR will equal Boost pressure (MAP) on the outlet intake manifold side of the EGR - won't work - pressure must be higher on the exhaust inlet side of the valve to get flow across the valve

ATXKJ · **Posted:** Mon Sep 29, 2008 4:05 pm

gmctd wrote:

He may have plumbed it, but it is not workable, as intake pressure is either Baro at zero Boost, or Baro + Boost at Boost event - EGP is always higher than Baro and Boost pressure - pressure equalizes to any lower pressure, not vice versa - I did not indicate the idea is not plumbable, but that it is not functional, as MAF output is Barometric\volume referenced against higher pressure of EGP reducing that volume

Actually the reason it might work is the reason the SEGR is so effective. That's the Flow Control Valve - it's primary purpose is to allow the exhaust to go into the intake - and it does this by choking down the airflow enough to create a venturi effect, that pulls enough of a vacuum to pull in exhaust.
However that means the FCV by itself is a real performance killer - because it chokes the intake on a regular basis - That's why the SEGR disables it.

Farmboss claimed lots of miles with no problems - but with no details - no one else confirmed it.

gmctd · **Posted:** Mon Sep 29, 2008 6:06 pm

Agreed, he could claim that with all veracity, as it does not work, therefore cannot cause failure or detrimental operation - it's just diverting flow from one end of the manifold to the other end = same difference

bewestro · **Posted:** Mon Sep 29, 2008 6:34 pm

Ahh, I was under the impression the exhaust was introduced AHEAD of the turbo, where there would be suction, not after it. It struck me as strange, as this would allow crusty soot through the turbo, but... it seems they've done equally strange things elsewhere anyway, so I didn't think much of it.

This is why I will never touch a screw on that thing without consulting LOST first.

Thanks for clearing that up!
--Ben

P.S.: Phooie.

gmctd · **Posted:** Mon Sep 29, 2008 8:05 pm

Sometimes new ideas are breakthrus :idea:

, othertimes they're breakdowns :evil:

, or even breakups :-)r

- try never to discourage contribution of ideas

jmoomaw · **Posted:** Tue Sep 30, 2008 7:08 am

Being new to many things, this thread expands my understanding of what I am working with...
Thanks...

Not to beat a dead horse... (EGR idea?)

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