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Old 11-12-2012, 06:22 PM   #1
noonagon
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Default PCV Valve and routing question

Looking at this post on IWSTI it seems like the diagram does not show the pcv system going to the heads. I have a 2007 sti and it seems that the PCV is connected tot he crank, both heads and the throttle body. There is also a second set of hoses connected to the heads as well just in front of the pcv valve lines.

My question is, how do all these hoses hook up?

So far I am thinking,

Head-(PCV-Throttle Body-Crank)-Head

Head-Crank-Intake-Head

Is this correct? I am lost
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Old 11-12-2012, 06:29 PM   #2
the suicidal eggroll
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What do you mean it doesn't show the system going to the heads? That diagram is exactly what it looks like, and the port on the intake closest to the turbo runs directly to the two heads in the diagram, so I'm not seeing what you're referring to.

It doesn't go to the throttle body either, it goes to the manifold, also shown in the diagram.

The second set of ports that you're referring to just go head-crank-head. It's just used to balance the pressure in each, it doesn't run anywhere else.





There are three separate systems, two of which are shown in the diagram. I've listed the connection points in order from left to right when looking at the engine (passenger side to driver side).

1:
intake-crank-manifold (this line has the PCV valve in it to prevent pressurized air from the manifold from pushing its way back into the crank in boost. This is also the line that causes problems when switching to a blow-through MAF setup, since this line allows the manifold to draw air directly from the turbo inlet)

2:
intake-head-head (this is the one that routes through the hard line attached to the stock TMIC)

3:
head-crank-head (this one is hidden under the manifold, you can't really see it until the manifold is pulled)

Line 3 is only on the EJ25, the EJ20 does not have this one. This is where the extra crank vent comes from when people do a hybrid setup (2.5L short block with 2.0L heads).

Last edited by the suicidal eggroll; 11-12-2012 at 06:36 PM.
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Old 11-12-2012, 06:58 PM   #3
noonagon
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Quote:
Originally Posted by the suicidal eggroll View Post
What do you mean it doesn't show the system going to the heads? That diagram is exactly what it looks like, and the port on the intake closest to the turbo runs directly to the two heads in the diagram, so I'm not seeing what you're referring to.

It doesn't go to the throttle body either, it goes to the manifold, also shown in the diagram.

The second set of ports that you're referring to just go head-crank-head. It's just used to balance the pressure in each, it doesn't run anywhere else.





There are three separate systems, two of which are shown in the diagram. I've listed the connection points in order from left to right when looking at the engine (passenger side to driver side).

1:
intake-crank-manifold (this line has the PCV valve in it to prevent pressurized air from the manifold from pushing its way back into the crank in boost. This is also the line that causes problems when switching to a blow-through MAF setup, since this line allows the manifold to draw air directly from the turbo inlet)

2:
intake-head-head (this is the one that routes through the hard line attached to the stock TMIC)

3:
head-crank-head (this one is hidden under the manifold, you can't really see it until the manifold is pulled)

Line 3 is only on the EJ25, the EJ20 does not have this one. This is where the extra crank vent comes from when people do a hybrid setup (2.5L short block with 2.0L heads).
Sorry, the one is the diagram looks as though it goes to the inlet and not the heads.

Ok, I have a FMIC, and I am really sorry for my ignorance in this subject, but it seems I only have one entry point on the Inlet for a vent to go to. I see the Head-Crank-Head, the Head-PCV/crank-Manifold-head,(is this just lines 3 and 1 together?)
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Old 11-12-2012, 07:09 PM   #4
the suicidal eggroll
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The diagram shows two systems (#1 and #2 in my list). The lower one, closer to the turbo, goes between the inlet on the left and the two heads on the right.

You must have an aftermarket inlet (doesn't really have anything to do with the FMIC, since the PCV ports are on the turbo inlet that runs under the manifold). Manufacturers will often merge the two lines that go to the turbo inlet into one so they only have to put one port on it. In that case they'd be merging the turbo inlet (intake) side of #1 and #2 in my list.

#3 is never touched by any setup, it's hidden under the manifold and just does its thing out of anybody's way. It's just used to equalize pressure between the crankcase and heads, it doesn't do any venting.
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Old 11-12-2012, 07:14 PM   #5
noonagon
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Quote:
Originally Posted by the suicidal eggroll View Post
The diagram shows two systems (#1 and #2 in my list). The lower one, closer to the turbo, goes between the inlet on the left and the two heads on the right.

You must have an aftermarket inlet (doesn't really have anything to do with the FMIC, since the PCV ports are on the turbo inlet that runs under the manifold). Manufacturers will often merge the two lines that go to the turbo inlet into one so they only have to put one port on it. In that case they'd be merging the turbo inlet (intake) side of #1 and #2 in my list.

#3 is never touched by any setup, it's hidden under the manifold and just does its thing out of anybody's way. It's just used to equalize pressure between the crankcase and heads, it doesn't do any venting.

I meant 1 and 2 lol, I have no idea why I said 1 and 3. Yes, I have an APS hard inlet, this clears the whole system up for me, thank you very much.
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Old 11-15-2012, 11:09 AM   #6
claythrow
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So which is the best way?

I have a used engine that has has the pcv system deleted and I can't figure out what the hell to do with all the wires and parts that I had before. I understand blocking the PCV valve on the perrin turbo inlet, but where to go from there?

I'd like to just put the PCV system back if I had some clear pictures or diagrams on how to do it. I guess I'll start by reading that 120 page thread : (
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