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Originally Posted by negcamber,May 26 2006, 06:27 PM
BTW...something that I noticed while doing this mod is that the air pump valve is attached to the intake manifold. Hot exhaust gases are passing through the head and into a port on the intake manifold that leads to the air pump valve. That does not seem like a good thing for heat soak.
Hot exhaust will not travel in that direction. It is a valved system to prevent that from happening. That air pump appears to lead to the intake manifold but it doesn't actually infiltrate it. It pumps air to the exhaust manifold via a separate route.
Hot exhaust will not travel in that direction. It is a valved system to prevent that from happening. That air pump appears to lead to the intake manifold but it doesn't actually infiltrate it. It pumps air to the exhaust manifold via a separate route.
Originally Posted by negcamber,May 26 2006, 07:47 PM
Interesting...where is the valve?
HUH? You, yourself called it the "air pump valve". Why are you wondering where it is? You're the one who noticed it. Remember your post? .......................................
BTW...something that I noticed while doing this mod is that the air pump valve is attached to the intake manifold.
BTW, it's called the "air control valve".
That valve is controlled by the "air control valve vacuum control solenoid valve", which is that little cylindrical thing that's attached to the back side of your air filter box.
HUH? You, yourself called it the "air pump valve". Why are you wondering where it is? You're the one who noticed it. Remember your post? .......................................
BTW, it's called the "air control valve".
I thought you must mean a different valve since you were saying that exhaust gasses can't go though the intake manifold. And that the air pump uses a different route.
Here is a pic of the manifold:
The gold topped assymbly above the green arrow is the air pump control valve. It sits on the manifold (the gasket that seals the air pump control valve is of the same material as an exhaust gasket). The small port above and to the left of the green arrow is the passage that leads to the air pump control valve. There is a matching port on the head that appears to allowsthe air pump to push fresh air through the head and over to the exhaust (according to the ESM, it appears there is a rail and passage system that allows the air to enter the exhaust stream).
Note that when the air pump control valve is closed, it appears hot exhaust gasses can flow through the head and into this passage in the intake manifold. I didn't see anything on the exhaust manifold side of the head to prevent this. The intake manifold passage on my car was black with exhaust soot indicating that exhaust gasses were flowing through the intake manifold up to the control valve.
The air injection ports in the exhaust ports are actually quite small. I'm not cylinder flow expert, but the vast majority of expanding exhaust gases are leaving the cylinder head from the large port through the exhaust manifold. (the easy way out) instead of snaking back through the air injection passage.
Some exhaust gases make it back through the air injection ports, but they are stopped by the air pump control valve. The small hole in your pic is for the air injection, farthest away from the intake port.
The large passage the green arrow points at carrries 200deg+ coolant much closer to the intake port than the air injection system does.
The greater cause of heating the intake manifold is the heat from combustion inside the cylinder.
I'm with Slow on this one. Exhaust will always take the path of least resistance. It's going to go out into the header and out of the car. It's not going to work its way into a dead end passageway. When the pump pumps and the valve opens, it will do it mainly when the engine is cold and the pump pressure will likely overcome any exhaust pressure in the system at that point.
P.S. If that gasket wasn't such a PITA to install AND if I could devise some sort of manually operated valve to allow for coolant flow for warm up, I'd do it myself. Of course, I'd unblock the plug that would allow coolant to go into the throttle body. For my winters, I need to have "carb heat". But I'd sure like to insulate the intake manifold.
The air pump moves a huge amount of air, it's built like a electric centrifugal supercharger. It's a closed system, the only way for the air to go with the pump on is to the exhaust ports.
Try pulling the fuse to the ECU (I think it's a 7.5A fuse marked "Back Up")
At a loss regarding your symptoms - your vac lines were fine IIRC. After about a dozen Hondata gasket installs, this is the first time I've heard of an erratic idle due to the gasket. Combined with the drop in performance and increase in fuel consumption, I'd venture to say it is not directly related to the gasket.
Try taking the VAFC out of the equation.
BTW, here's a cutaway view showing the passage that air takes from the air pump into the exhaust ports. Apparently the metal cover running along the head right above the header covers this passage.
As a side note, you can only remove this system IF you are using a Standalone EMS, or a PCM that doesn't support OBDII emission monitors such as the Mugen N1.
05-26-2006, 05:44 PM
You, yourself called it the "air pump valve". Why are you wondering where it is? You're the one who noticed it. 
Remember your post? ....................................... 
But I'd sure like to insulate the intake manifold.
It's a closed system, the only way for the air to go with the pump on is to the exhaust ports.
