PCV bypass for VW 2.0 FSI Description/DIY (long)

[saaber1]

Here are the results of a UOA done at 2711 miles after installing the pcv bypass. The question I was trying to answer is whether bypassing pcv and routing to exhaust, instead of to the intake, would have any positive or negative effect on the oil. It looks like it doesn't. That means that the bypass system is likely allowing adequate crankcase evacuation based on no negative effect on the oil. The full UOA is posted in the UOA section.

The red bars below are the post-bypass run. The pink bars are the pre-bypass run. The blue bars are what I predicted a non-bypassed run would be based on % city driving. In other words, any red bars higher than the blue are better than expected. Any red bars higher than the pink are better than a same mileage run that had easier usage (except for TAN of course where lower is better).

 

[saaber1]

Time to update this thread. My original thinking was to play it safe by using the stock pcv to regulate the vacuum from the exhaust nipple. Another safety feature is the check valve on the exhaust nipple.

After testing the vacuum in "wide open" mode (eliminating both the pcv regulation and the check valve), it pulls 0-3" Hg with a max of 5" for brief moments. This is a very safe level. This is about the same vacuum as normal operation of the stock system when boost is present.

There is also noticeably more power with the "wide-open" setup. I am going to keep it like this but may add a second exhaust nipple in the future to try to improve power even more. Should in theory still be at safe levels with 2 nipples but need to try it and measure to make sure.

 

[StevieC]

Could you not hook up an electronic vacuum pump to the PCV line that normally goes to the air intake and suck it out using the pump and existing PCV valve and vent it to the atmosphere? Illegal yes, but just talking.

Leave the breather line to allow fresh filtered air into the crankcase from the throttle body.

And pipe the intake section that would normally be sucking from the PCV to the air filter box so as not to upset the "unmetered" air leak normally provided by the PCV and possible set a check engine light or screw up the idle RPM.

 

[Bigsyke]

I think the conclusion on HT some time after that was exhaust slash cuts were a no go.

I currently have

http://zilvia.net/f/chat/279349-idea-2x-pcv-valves-series.html

2 pcv valves in parallel actually. Its still too inconsistent to know if Im actually pulling any more crank vacuum than with the OEM setup. The catch can inline does do its job, I went to homedepot and got 2 packets of the stainless dryer mesh screens and stuffed them in the catch cans.

 

[saaber1]

Originally Posted By: Bigsyke
I think the conclusion on HT some time after that was exhaust slash cuts were a no go.


DO you have a reference for that? I would like to see that please.

 

[shpankey]

Just some info on this from the MS3 forums. A guy there has the same setup..

I finally had enough time this afternoon to hook up a vacuum gauge to the catch can. I just want to point out that this is not a very scientific measurement, it is a $25 vacuum/boost gauge from Advanced Auto, so take it for what it's worth. Under cruising normally, light throttle I was seeing no pressure and no vacuum, a neutral condition. When I stepped on the gas I watched the needle fall somewhere between 2-5 inches of vacuum depending on how long I stayed into it. This is what I thought would happen, which after all was what I was after, a vacuum on the crankcase while in boost.

Source: http://www.mazdaspeedforums.org/forum/f33/crankcase-evacuation-system-39239/

 

[Texan4Life]

Originally Posted By: JAG
So this works based on Bernoulli's principle, right?
http://en.wikipedia.org/wiki/Bernoulli's_principle

Has there been any evidence that this setup sometimes can allow a flow from the exhaust to the crankcase?


That was my first thought.. "Oh noes an exhaust check valve!"

I don't see a problem but is there a why to check and make sure it is still functioning?

I had a $550 diverter valve fail on my caddy from what I suspected was a bad exhaust check valve. So I put on two new check valves as insurance for the new diverter valve.

not to sure what will happen if the valve fails in the OP's case.

 

[zoomzoom]

Saaber are you running this without the check valve now?

 

[NEMF]

Can someone tell me if I'm doing this right? I'm trying to bypass the PCV system on my 2006 Audi A6 3.2. I'm venting to the atmosphere, not the exhaust. My PVC plugs directly into my intake manifold and then there is a line coming off the other end of the PVC. I know I have to remove the PCV from the intake manifold and then plug that hole. After that I'm lost. Zoomzoom's instructions say to block off the rear PCV line. I don't know which line that is. I'm thinking since my car is different than zoomzoom's and I don't need to do that since my PCV plugs directly into the intake. Where do I attach the hose? Do I attach it to the PCV? Do I get rid of the PCV completely?

 

[NEMF]

I meant saaber1, not zoom zoom.

 

[NEMF]

Ok so I've figured out I need to attach the hose to the PCV and then plug the crankcase side of the PCV, but I don't know where that is. Here are pics of my engine:

http://sphotos.ak.fbcdn.net/hphotos-ak-s...5_1445373_n.jpg

http://sphotos.ak.fbcdn.net/hphotos-ak-a...9_6555162_n.jpg

http://hphotos-snc3.fbcdn.net/hs510.snc3/26783_413628613407_513113407_5279737_7472828_n.jpg

 

[NEMF]

Update: there's two hoses that go from the valve covers (one hose on each cover) and down to the bottom of the engine. These hoses are sucking air. Do you think they are venting the crankcase? If so, do they need to remain open and then plug the line with the check valve going from the air intake to the crankcase?

 

[zoomzoom]

you need to cap the hose that returns the PCV fumes back into intake and vent out hoses from both valven covers and crankcase..

also I assume there is source of vacuum for you PCV system you need to cap that as well