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TOPIC: 1999-2004 Honda Odyssey 3.5L V6 Manifold Cover

1999-2004 Honda Odyssey 3.5L V6 Manifold Cover 12 Jan 2020 11:57 #1

  • Jette
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Greetings All!
I am writing this, as I have searched the forums and have not seen any questions, comments, or ideas about this.
In my 2002 Honda Odyssey, which GadgetMan Michael Lee completed wonderfully grooved for me , while I have noticed power improvements, and a much smoother idle, I believe I can still get more efficiency out of this thing.
The picture is of the Manifold Intake Cover on the bottom side. The red circles/ovals are the grooves on the two sides??!?!?! The yellow circle/oval is where I believe the EGR recirc flows back through [and no this is not currently blocked, as in many Honda cases].
Several years ago, before I knew about GadgetMans' Grooves, I learned about these, because for some reason, I don't remember, probably rough running, I pulled this cover to see what was the matter. The grooves on both sides were filled COMPLETELY with carbon. I scraped them all clean, and sprayed the whole thing with Carb/Choke Cleaner, and put it back on, and there was noticeable improvement.
I have an idea which I am CONSIDERING [by opening this discussion]:
Now that I am GadgetMan Grooved, I am CONSIDERING what may be able to be done about these grooves, if anything?
I also recall seeing fluid inside the intake puddled [I don't recall if it is gasoline or not, but it is clear, and the inside of the manifold is orangish color, like gasoline [and not antifreeze], which may indicate an injector/fuel line leak?~~
I am curious what, if any, others have to say about this, based on knowledge, or even scientific speculation experience.
Why I might NOT consider doing this is because I believe this is part of the EGR valve flow and I do not really understand how these grooves do or don't impact that process.
Thanks in advance for your thoughtful insights.

Jette

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Last edit: by Jette.

1999-2004 Honda Odyssey 3.5L V6 Manifold Cover 12 Jan 2020 14:28 #2

  • GregK
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Jette -
a while ago, I was considering designing a vessel that was combination air-oil seperator catch can and EGR filter vessel. I never got around to it.
Here is what I was considering: Blowby still has burnable fuel in it, as well as water vapour. a seperator is supposed to get those vapours to condense, but the engine actually runs BETTER on them. Further, the EGR system is meant to lower NOx emissions as well as recycling exhaust vapour and unburned fuel back into the engine. Trouble with both of those streams back into the engine is the waste products - all the carbons, hydro and otherwise. that gum up and cause the engine to degrade, as well as increase it's consumption of fuel. would bubbling hot EGR gas through the condensed PCV vapours, and then re-introducing that product back into the intake airstream upstream of the throttle body, displacing and warming intake air, further reduce fuel consumption and by extension emissions?

Perhaps you might be the person to test my theory, Jette. ;)
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1999-2004 Honda Odyssey 3.5L V6 Manifold Cover 25 Jan 2020 23:22 #3

  • Tracy Gallaway
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Hi Jette.

I am guessing, lacking more info, that your Honda is a V-6? The area at right in the pic is where EGR gas enters. Then it looks like there are 3 holes on each side of this aluminum casting, each at the end of an individual channel. So I'd guess that this is Honda's way of restricting/metering the EGR gas flow into each cylinder's intake port. Possibly this structure is intended to act as a "carbon trap" to catch and reduce carbon buildup from the EGR gasses. I'd be curious to know if Honda specifies a maintenance interval to pull and clean this casting out as you did.

The liquid and orange gunk is probably water condensation, and the orange stuff sounds like condensed crankcase gasses, probably from the PCV system, if it has one.

As Greg K describes, there are various ideas of capturing/processing/re-using EGR and crankcase gasses and their hydrocarbons. Many Rube Goldberg ideas present themselves w/ this.

All I've ever found effective was to block the EGR, and use an air-oil separator to remove water and oil condensates from PCV system flow. I prefer to just try to eliminate all the crud that's going back into the combustion chambers. but, that's just me!:lol:

Tracy G
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1999-2004 Honda Odyssey 3.5L V6 Manifold Cover 29 Jan 2020 03:40 #4

  • cj donaldson
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Hi Tracy. Do you know what kind of complication I would run into if I where to delete my egr valve. I agree with your points of stopping all this crude going back through. My inlet manifold is dirty black from carbon buildup
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1999-2004 Honda Odyssey 3.5L V6 Manifold Cover 29 Jan 2020 18:27 #5

  • Tracy Gallaway
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Well, CJ, probably some kind of computer code. I don't know that blocking the EGR flow would cause any damage. There might be some sensor that monitors the EGR system. I'm not directly familiar with your Honda.

Maybe someone else here is...?

Lacking any more info, I'd say try it and see. But if you have to go thru a Smog Test, you probably ought to reconnect the EGR some time before the test.

Tracy G
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1999-2004 Honda Odyssey 3.5L V6 Manifold Cover 29 Jan 2020 19:05 #6

  • GregK
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Tracy, consider these:
A MAP sensor could see a commanded EGR injection (reduction in manifold vacuum, meaning an increase in engine demand), then upstream O2 sensors may see a corresponding drop (or change, at least) in exhaust temperature... lots of potential codes to work around/through if they’re not seen as expected.

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1999-2004 Honda Odyssey 3.5L V6 Manifold Cover 30 Jan 2020 13:19 #7

  • Tracy Gallaway
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Greg, I agree in theory that changing anything re: EGR can cause changes in engine sensor inputs, and therefore cause codes.
One has to consider in this engine's case. whether any benefit in blocking off the EGR, or in modifying it in some way--is worth the effort. Or would it be simpler/easier to accept the carboning-up the EGR causes, and plan on occasionally pulling this cover and cleaning it out.

As far as the carbon buildup in the intake tract, and especially intake port/ intake valve/ combustion chambers areas-- one can occasionally use any of the many specialised cleaners available today to keep this under control. IMHO, of course!:)

Tracy G
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