Ok everyone, I have been researching placement of oil catch cans in relation to the pcv system. I have a question that pertains to a possible vacuum leak they could cause if I were to use a breather style vs a sealed style catch can. I would like to use a breather style seeing as it vents vapors to atmosphere, therefore making it more efficient than a sealed can in the evacuation of oil vapors (I understand baffled vs non-baffled has an effect on efficiency as well). Anyway, the picture below is a diagram of the setup I would like to run. I currently have the breather filter on my valve cover (due to the ZPI Turbo kit intake style) and it has given me no issues. On to the issue now. I recently removed my intake manifold and to my surprise, I had about 1/2 quart of oil that had accumulated in the darn thing. I figured initially that the seals in my turbo had gone bad and therefore allowed oil to pass through the intercooler and charge pipes. At this point, I removed the piping and intercooler to check this theory, but they were free of any oil residue. The only thing left that could be causing this oil accumulation would be the pcv system that leads from the rear of the valve cover directly into the intake manifold. My solution to this is to place an oil catch can in line with this system. A check valve would also be needed in order to prevent a major boost leak from the breather on the catch can while in boost. So at this point, boost leaks are controlled by the check valve. The issue at hand is now that when the system in under vacuum and not boost, would this filter on the catch can basically cause the pcv valve to be bypassed (seeing as it would pull vacuum through the filter instead of opening the pcv valve and pulling vacuum through the valve cover)? I am worried about a vacuum leak registering with the ECU and throwing a CEL as well as possibly causing drive-ability issues while not boosting. Based on this scenario, which style can would be more beneficial to use; breather or sealed? Feel free to chime in with any knowledge on the subject, whether it pertains directly to the tC or if you have experience with catch cans on previous cars.

 

I went through A LOT of research when setting up a catch can system for my Evo and went with a breather style catch can. I block off the intake manifold nipple and intake pipe nipple and ran both valve cover blow by nipples to the catch can. Runs great with no issue. No check valve either. Just straight hose from both nipples on the valve cover to the catch can. A lot of guys don't even use a catch can, the run both hose to the ground and let it free.

 

Thanks for the info man! I will definitely consider that option. It just so happens that a lot of my research has been coming from the evo/dsm forums as well.