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PCV plumbing

5K views 13 replies 5 participants last post by  BO185 
#1 ·
Took a deep breath, we're going to finish this thing...

I have a Sheet Metal intake, DBW TB, relocated coils with aftermarket valve covers, alum intake tube going to both fenders, Moroso PCV can and AN fittings in each valve cover. I have one port on the back of my intake where I currently have my MAP Sensor plumbed.

To add PCV ingest I'll called it, I guess my choices are:

-add a fitting under the intake tube just ahead of the TB.
-add a fitting under the intake itself
-share the fitting on the back of the intake with the MAP via a "Y" hose.

Thoughts?

Thanks,
Charlie
 
#5 ·
I'm using a Holley Dominator for the ECU, so I'm MAF'less- Speed Density. I can't use a vented cap on the valve covers as they don't make one for the one's I have.

It's been a bit since I thought about all this... Don't I have to complete the system by essentially pulling from the PCV can back into the motor? What programming do you to do based on how your managing PCV?

Thanks!
Charlie
 
#8 ·
You need a fresh air in so either make/find a filter for a valve cover or hook 1 valve cover to the intake tube this will be you fresh filtered air in. The your valve tray should have the port in it for the PCV unless its a truck motor then it will not you never stated what motor you have. And you use the opposite valve cover as dirty air into the intake. Add a bung to your intake were ever is easiest. I would not Y it into the MAP sensor.

Also pictures would help too.


Being SD the ECU should handle it but might have to fine tune the idle and such.

Now all that said you can run an open crank case. And not even have a PCV system. Just run the valve cover fittings to a remote location and add a filter there. It might drip oil but will be an open system.
 
#6 ·
I think all he's suggesting is to tune the engine in the normal manner after you've completed the PCV setup - so that you compensate for the small vacuum leak caused by having a PCV system.

For what it's worth, the LS3 PCV system draws filtered air in from the intake tube, connected at the passenger valve cover. The "dirty" air comes through passages in the valley cover plate. A connection is made from the valley cover plate to the throttle body. If you use a "can", you'd connect from the valley plate to the can, and from the can to the throttle body. Valley covers vary for various Gen 4 setups.
 
#7 ·
For what it's worth, the LS3 PCV system draws filtered air in from the intake tube, connected at the passenger valve cover. The "dirty" air comes through passages in the valley cover plate. A connection is made from the valley cover plate to the throttle body. If you use a "can", you'd connect from the valley plate to the can, and from the can to the throttle body. Valley covers vary for various Gen 4 setups.
To avoid confusion.
The stock LS3 system draws clean filtered and meter'ed air from intake tube, meaning the MAF has accounted for it so its not a "vacuum leak". to the pass valve cover in which moving through the motor picks up oil vapor etc and moves through the port on the valley tray through a tube to an port on the intake. The dirty air connection is on the on intake itself not the TB on all LS motors Gen III and IV. The only port on TB is Gen III DBC TB of which this is the fresh air inlet not dirty air.

So in short on car motors dirty air moves from valley tray to intake port aft of the TB. On truck motors it uses the drivers rear valve cover port and dirty air moves through it to the top side of intake and burned.
 
#9 ·
Here's a pic of the engine, not much you can see as it pertains to this thread.

I drilled and nutsert'ed some threads into my valley cover with the intention of putting a cover of some kind over the wires running from the firewall and out under the intake. Good idea before it was all actually installed. :) There's no way to get a cover of any substance/size in there and with there being two connectors between the sides of the intake runners, I have to put the intake on, then run the wiring. I also ran my head cooling port plumbing under the intake to the water pump. Just no room and/or too hard for what it would net out to be.

I'm going to get a new valley cover without the front port on it. That will leave the fittings on the covers, y'iing into a line going to my catch can and then a line running from the catch can to a bung/fitting I'm going to add in my intake tube ahead of my TB.

That sound like a plan?

I have to start reading up on my Dominator programming again.

Charlie
 
#10 ·
I'm going to get a new valley cover without the front port on it. That will leave the fittings on the covers, y'iing into a line going to my catch can and then a line running from the catch can to a bung/fitting I'm going to add in my intake tube ahead of my TB.

That sound like a plan?

I have to start reading up on my Dominator programming again.

Charlie
You have it back ward. The line from intake ahead of TB to one valve cover the other valve cover goes to the catch can then to a port intake for vacuum.

If you hook it the way you say you will suck all the dirty air threw the TB and gum up the idle cicrut and TB blade.

If you have a port on the valley use it!!
Run from intake tube before TB to pass valve cover then from valley for to a bung in the intake. You can Y the valve covers into the intake tube but not really worth it GM quit doing that years ago.
 
#12 ·
If you read my post Ricks info is wrong the stock Ls3 uses a port on the intake itself just behind the TB. You need intake vacuum.

You need to connect to the intake itself. Either add a port via drilling and tig weld a bung or use an existing port.

If you can't then just run a open system with a filter.

They way you stated before will not work.



Do you have vacuum brakes? Or a port for it if so tee into it for PCV.

A PCV system needs engine vacuum for it to work correctly this is accomplished by hooking to the intake itself.
 
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