Currently installing a trick performance stage 3 kit on my lq9 Silverado. I am using a dual valve catch can and oil fill cap from RX performance and plan on following their instructions for the pcv line routing. My question to ya'll is when I install the catch can, will there be unmetered air entering the system? I showed my tuner the diagram of the install along with the install instructions from RX and he claims this setup will allow unmetered air in causing "fuel trim swings in vacuum" Please let me know what ya'll think. I am including a picture of the diragram from rx's install instructions.

 

I don't think so. The system will pull vac from the valve cover using the intake until you go into boost. Then it will pull vac from the valve cover using the turbo inlet. Not sure how in metered air is entering the system.

 

Does the catch can have an open breather on it? or is it a sealed unit?

 

the catch can is a sealed system. The only open source for air would be the check valved oil breather cap

 

thats good then! Because if it didnt have a check valve it would pull vacuum through the catch can under normal conditions(no boost).

 

I'm pretty sure your tuner was referring to the line right behind the throttle body. Under vacuum this line would allow unmetered air into the intake manifold. But I think most the rx dual valve catch cans have a single or dual check valves... If so your good.

 

Did that diagram come from the catch can manufacturer? I'm not sure why one blue line goes from the valve cover and the other goes to intake vacuum(Behind the throttle body). Then there is another line before the turbo.

I run 2 separate catch cans hooked to each valve cover. Then the catch cans vent to atmosphere with a small screen.

 

I'm not sure on the line from behind the throttle body either.... I'm running this same setup though, but I have both lines coming off of each valve cover to the cc then one line to the turbo intake tube (which helps pull pressure from the block when boosting).

 

gadget and jordan -

i believe the blue line behind the TB is for reg driving vac. once in boost that check valve closes and the line to the turbo inlet is now the vac source while in boost.

 

Yes choda, that's how it's intended to work as far as their instructions go. Once I get the build completed and everything completed I guess I'll know if there's any problems. What do most of ya'll do with the Evap line coming out of the intake? Most say just plug it and it's fine...