Hi everyone I know they're many posts about this topic but I'm finding mixed information about the PCV.

So I purchased a brand new OEM PCV valve and did the blow test before install (I can only blow through one side). But when I do a boost leak test, it's leaking from the PCV valve.
I can't get my car to hold more than 18 psi because of the valve.

Is this PCV valve faulty that I got or do I remove the PCV valve when I do a boost leak test ?

Thanks

 

our pcv cannot leak enough to affect max boost IMO (genuine mitsu part or generic), not more than what would leak thru your valves and rings

I dont think a boost leak test helped me solve anything

 

So I'm better off removing the PCV valve and plugging the hose when doing a boost leak test ?

 

yeah sure. its definitely better to test in small sections so you can get a better idea where the hissing is coming from. but again, I dont think that would help me solve anything
do you have a boost pill or a manual boost controller?

 

I just have a electronic boost controller. I'll do some boost leak testing without the PCV and see how much I hold

 

I did another boost leak test without the PCV and I'm holding 26 psi so I should be good ? I am running 25 psi peak boost

 

are you saying you were pushing boost thru the pcv into your block? thats super odd

 

Yeah the PCV is letting air into the valve cover then coming out of that stem on the right side of the cover. Just confused if it's normal or not because the PCV valve is brand new.

 

that is super weird if it cant keep pressure with steady air supply. I tried the cheap ones from autozone and they hold fine(not perfect). I actually have 2 in series but thats because I have a custom PCV/catch can set up

 

I thought my old PCV valve was bad because it was leaking but it's operating the same as the new one. So that's why I think it's normal operation? But I could try to get a aftermarket one too and see how it goes

 

On one of my other cars I also thought the PCV was bad because it was leaking and got a new OEM replacement, which did the same thing. From what I've read it seems to be normal operation for the PCV's to pass limited amounts of air in and out of the intake manifold so it can flush the blow-by contaminants out of the engine more effectively.

 

I disagree. there's already low pressure on the intake side whenever you have positive crankcase pressure

 

Of course, but even at idle the PCV counts on the vent to the intake tube to build a small air current through the engine and flush the blowby contaminants through the VC. I've seen OEM PCV's on other boosted applications leak a smaller amount of air(boost) and my guess is that it was designed to do this same flushing method, just in the opposite direction. I'm not 100% sure on this and I'm not sure if there's any detriment in adding a check valve behind the PCV to seal boost, but I suspect this is at least part of the reason why OEM's decided to create millions of PCV's that are very bad check valves lol

 

well if you have blow-by you already have leaks to push air out. I'd say "a little boost leak" is fine. I have 2 OE PCV in series to block the leaked air from the 1st PCV (and to make sure theres back up if it completely fails, if thats even possible)

 

I have one of those 1/2" high flow check valves in series with the OE PCV on my other project car and it seems to work well so far. The PCV takes care of metering the right amount of air for stable idling and the check valve seals in the boost from leaking out.