How are LQ4's pcv system set up?

[txarkitekt]

...leaving the passenger side valve cover connected to the nipple on the TB...

Then take a hose from the driver's side valve cover to the inlet side of the Catch Can, then a hose from the outlet of the Catch Can to the passenger side of the intake...

And since you have the emissions crap taken out, just plug the brass nipple on the driver's side of the intake behind the TB. That should get you the correct routing.

'clean' and 'dirty' are non-technical names for the two sides of the PCV system. Clean (air)= System Input, Dirty (air)= System output


The clean side connects at the throttle body and valve cover for a N/A LSx. This side is designed to flow fresh filtered air from the air intake (atmosphere) into the engine crankcase.

The dirty side connects from the valley cover or opposing valve cover to the intake manifold plenum chamber (engine vacuum).

Blowby can flow out the clean side when dirty side flow is insufficient to overcome blowby production...

+1 on getting a better catch can.

Thanks for linking the diagram Jay. It illustrates what I was saying. Sometimes a picture does better than my retardedly elaborate/confusing verbage.

Nevermind, I saw your diagram when I went home on lunch break. I couldn't see it on my phone earlier because the screen is so small haha

I appreciate all of your help guys! And I ordered a revxtreme can on my break too lol

Yeah--adding an inline PCV would be the thing to do. And the Revxtreme Catch Can is a great purchase!

[BlueZee28]

Ok so I just got back from the dealership, and they said that the '99/'00 LQ4's don't have an actual PCV valve??? They said that all those blocks got was the little pressure stem that goes in the driver side valve cover. They showed me what it looked like and it looks exactly like what is on my valve cover. So....what should I do?

[txarkitekt]

Ok so I just got back from the dealership, and they said that the '99/'00 LQ4's don't have an actual PCV valve??? They said that all those blocks got was the little pressure stem that goes in the driver side valve cover. They showed me what it looked like and it looks exactly like what is on my valve cover. So....what should I do?

That is essentially an inline PCV. You can either ditch it and go buy an inline PCV or just attach a hose from the driver's side PCV stem and run it to the inlet side of the Catch Can.

Depending on age/condition of the existing PCV stem, I think I would pay the extra $4 and put a new one in.

[BlueZee28]

It doesn't look too bad. The motor had 100,xxx on it though. It actually clean up rather nicely when I had them powdercoated.

[txarkitekt]

The mechanics of a PCV can wear out over time..and mileage. If it was me, I would definitely make sure my PCV works so that my investment in the Catch Can works to the fullest extent.

[BlueZee28]

I will, but I really don't think I have time to before the tuner gets here on Saturday. I still have to install the torque arm, finish the transmission wiring and re-locate the ALDL or whatever it's called, and wire up the alternator before 3:00 on Saturday, just so I can have it running for him to put a base tune on it, then it goes to the exhaust shop next week, and when I get it back from there and tagged, I will go back and probably put a new PCV valve in, and install the rest of the interior and loom all the extra wiring under the hood lol. That, and I'm fighting a soon-to-be nasty cold, so it really sucks lol

[ff_jeff]

I know that on my LS1 that if I take the line from the passenger side valve cover, and switch were it attaches to the intake with the valley cover line, it will actually cause problems. If you hear a squeaking noise, and you take the oil cap off, and it sucks in a lot of air... you got it wrong. And might try switching it. On the newer Ls1's they don't have a driver side pcv barb or line. Instead they have a valley cover that has one. And it supposedly works better. But on my old truck I noticed a similar problem when I put a Ls1 nitrous plate on a truck intake. It blocked off a port, and cause the crankcase to have really bad vacuum. This was remedied by moving the line to a catch can instead. like this


I drilled and tapped a 3/8 barb on the driver side valve cover. And drilled and tapped 3/8 barb on the oil fill cap. Capped all other elbows and open ports and ran the 3/8 hose from both valve covers to a filtered catch can. This prevents ANY oil or vapor from entering the intake. This method is also useful for boosted applications so as not to pressurize the crankcase.
Sorry so long.
Note: This type of catch can can not be used if you return pcv line back into intake. This will allow unmetered air to flow into the intake, and will cause a lean condition.

[Sleaper]

I know that on my LS1 that if I take the line from the passenger side valve cover, and switch were it attaches to the intake with the valley cover line, it will actually cause problems. If you hear a squeaking noise, and you take the oil cap off, and it sucks in a lot of air... you got it wrong. And might try switching it. On the newer Ls1's they don't have a driver side pcv barb or line. Instead they have a valley cover that has one. And it supposedly works better. But on my old truck I noticed a similar problem when I put a Ls1 nitrous plate on a truck intake. It blocked off a port, and cause the crankcase to have really bad vacuum. This was remedied by moving the line to a catch can instead. like this


I drilled and tapped a 3/8 barb on the driver side valve cover. And drilled and tapped 3/8 barb on the oil fill cap. Capped all other elbows and open ports and ran the 3/8 hose from both valve covers to a filtered catch can. This prevents ANY oil or vapor from entering the intake. This method is also useful for boosted applications so as not to pressurize the crankcase.
Sorry so long.
Note: This type of catch can can not be used if you return pcv line back into intake. This will allow unmetered air to flow into the intake, and will cause a lean condition.

The way that the diagram shows is to keep everything "emissions legal" and so the system remains closed. Not saying that Jeff's way won't work, just different ways to get there.

Also, I'm not sure you need an inline PCV because the catch can that you bought, RevExt, has one within. If you would have gone with a different catch can, then you would need one.