Thanks for watching, and thanks for the comment!

The Subaru engineers did a TERRIBLE job in designing the PCV system because there's still a LOT Of oil that gets sucked in the engine. Which is why AOS and catch can are so popular and a must have to avoid detonation / knock.

@@neuspeed79I’m sure you could have emgineered a better system. Besides, AOS and catch cans are completely unnecessary at stock power.

@@SonikJesus You couldn’t be more wrong. Because the pcv sucks, is why a lot of engines fail. Blowback builds up over time within the engine and the heads / cylinder get blown. AOS is a reliability mod.

Absolutely, and that is why I made the video :-) Glad that it was helpful and thanks for watching! You should check out the video about Crankcase pressure too: kzfaq.info/get/bejne/fqemq82EybfXiH0.html Stay Tuned!

@@FlatironsTuning ive watches some of it so far, will watch the rest pretty soon. id already watched all of the other ones. i was hoping to drastically simplify the system and remove as many hoses as possible, but not im thinking just to add an aos. apart from the vacuum leak from said cracked pipe (which i eventually sourced, part no. 99071AB352), i dont have any other issues with the system other than it being in the way of literally every maintenance task. lol. seems like the pcv system is half the reason there is a snake pit sitting on top of subaru engines.

Thanks for watching and Stay Tuned!

Awesome compliment. Thanks Ted!

Wow, that is a huge compliment Dauv. Thanks for your support and thank you for your business!

Will Do. Thanks Vernon!

Glad that the video was helpful. Thanks for watching and Stay Tuned!

what was the solution

​@@06wrxRAR dry sump

That is awesome Dagan. Very glad that we could help, and thanks very much for your support!

Thanks very much for the comment. Glad that we had the information that you needed! Stay Tuned!

Thanks very much and please share if you can. Thanks for watching and Stay Tuned!

Very glad we could help! Thanks for watching and Stay Tuned!

Thanks for your comment, and thanks for watching!

Thank you for watching!

Thanks very much! Glad we could help and Stay Tuned!

Very glad that we could help! Thanks for watching and Stay Tuned!

Awesome comment. Thanks Case, and thanks for watching!

Hey! I would love to run something similar to this, any way you could make a quick video explaining what you did? I've read through a lot of forums and watched many videos but I'm having trouble grasping exactly what I need to do.

@@Mqxwell Are you asking about a dual catch can set-up specifically?

@@FlatironsTuning Yes, but I have also read a lot about rerouting the high load lines in the PCV system running them to 2 catch cans. At least I think that's right, not 100% sure but this forum thread goes pretty in depth - forums.nasioc.com/forums/showthread.php?t=2870817 (Specifically mrsaturn7085's posts) I'm just not sure what to make of it. I'd love to see somebody's set up and specifically going from a stock set up to dual catch cans. This video did help a lot but I'm not sure which changes to make. I've also seen a few videos showing the system off but I can never tell what's changed and where I'd get the materials. I can find catch cans, but would I need extra hosing? I'm already having to purchase a lot for my bugeye, and I know that's just a part of the Subaru life but if I can save a few hundred dollars on something I don't actually need, I'd love it!

No problem. thanks for watching!

Thanks for your question. That is a tricky one. I'd actually say that for most applications there are some advantages of keeping the PCV system largely in tact so that you can use vacuum to scavenge the crankcase. Going to atmospheric venting is appealing at first, but in doing that, you lose all ability to pull any kind of a vacuum. More than anything, the degree that you need to modify the PCV system depends on how much oil you are moving through it. If it is very low, then you most likely don't need much of anything. I hope that helps and Stay Tuned!

Thanks for watching Peter!

Thanks for your comment, and thanks for watching. Stay Tuned!

Awesome! Thanks for watching and glad it was helpful. You should check out this video too as it may be similarly enlightening: kzfaq.info/get/bejne/fqemq82EybfXiH0.html Thanks for watching and Stay Tuned!

Awesome comment, and glad that this video was helpful. Thanks for watching and Stay Tuned!

@@FlatironsTuning I'm hoping you will start producing videos on the 08-14 WRX and/or STI. I've done my own work my '13 STI, but I am always up for learning from professionals.

@@Thaib0xer69 Thanks Alexander. We have a 2014 WRX that is our Pikes Peak race car, and we have a fair amount of content on that on our site. But we are always trying to make more :-) It has been a bit busy of late, but we have a lot more content in the works, so please subscribe and check back. There is a lot more to come :-)

Absolutely! Glad that the video was helpful. Thanks for watching and Stay Tuned!

Glad the video was helpful! Thanks for watching and Stay Tuned!

Thanks Nicholaus, and thanks for watching!

That is awesome! We are going to come back to this here shortly so stay tuned for a new video or two :-) Thanks for watching and Stay Tuned!

@@FlatironsTuning I'll definitely be looking forward to it. I'm pretty impressed with the Subaru pcv system. It's just slightly more advanced than the one on my ford, lol.

Thanks for watching the video and I hope it was helpful. Stay Tuned!

Excellent! Glad to hear it. Thanks for watching and Stay Tuned!

Very glad that we could help! Thanks for watching and Stay Tuned!

At some point, yes, we will talk about this. Stay tuned!

The short answer is yes, but you have to tune for the atmospheric configuration. I'd recommend going through this video that we made on the topic: kzfaq.info/get/bejne/bMiAmtad1b3OkZ8.html Hope that helps and Stay Tuned!

Thanks for your question. You have the function of the PCV valve correct. First, I'd say that it is not that common of a failure point, so I would say that isn't a reason to remove the valve. As to why it is there, it is to help ensure that the crankcase gasses are still being vented when the engine isn't under positive boost. If the valve wasn't there, then there could be a build up of those vapour's, especially on a street car that isn't in boost that often. This is less of an issue on a race car though. The other purpose that a PCV valve serves is to ensure that if any positive pressure is built up at WOT, it can be reduced when the throttle closes, and by the same token, it helps to ensure that as you go into WOT, the crankcase should be starting under slight vacuum rather than atmospheric pressure, etc. It is a small difference, but on a street car especially, it can make a big difference. Even on some track cars. Hope that helps and Stay Tuned!

Yes, the metal line on the intercooler that connects the two valve covers is the same as on the 2.5 Liter engines, but the 2.0 Liter heads are missing the second set of breathers. They did start putting them on the STI 2.0 liter heads though, but I'm not sure exactly what year. If you see a 207 head with 2 fittings on top of the valve covers, then the routing would match what we go over in the video. Hope that helps, and thanks for watching!

@@FlatironsTuning can't you just ditch the crankcase breather to valve covers setup? The 2.0 litre never had it so what's the need it would clean up the engine bay of plumbing.

@@jordanp6420 I wouldn't recommend it. It does serve a purpose, but if for some reason you have to remove them, yes, you are correct, the 2.0 liters here in the US never had those connections. The EJ207 did get them eventually though. On a street driven car, they are far less necessary. But if you track your car, the purpose of that connection is to help the oil drain back from the heads to the pan. I hope that helps, and thanks for watching!

Thanks for that comment Gerardo. In short, I would agree with you. My current take is that if you are not using much oil if any, the need to intervene with the PCV system is minimal if any. The need for something like a catch-can or AOS only starts to come into play if you are seeing more oil consumption and you want to make sure that the oil isn't making its way into the engine, etc. Thanks for watching!

FlatironsTuning Thank you! 👍

You bet Ryan. Thanks for watching!

Thanks for the suggestion. We might have to consider that. Basically, you would just have to install the catch cans as jumpers in the two lines that go to the turbo inlet. But it definitely makes sense that a clear representation would help. We'll keep it in mind. Stay Tuned!

@@FlatironsTuning you’d be surprised! A lot of people don’t understand any of the catch can install videos because they can’t see what their dealing with because of the the intake manifold hiding the routing. So people get overwhelmed and confused.

Thanks for your question. The PCV valve should close under pressure. If you are thinking that it is stuck open, I'd say the first step would be to remove and inspect the valve. While it is off, block both ends of that connection and try the test again. If the leak goes away, I'd definitely say it is time to replace the PCV valve. If it does not change the result, I would recommend disconnecting parts of the intake system (take the intercooler off for instance), so you can pressure test specific areas of the intake track until you find the leak. Testing from the throttle body, and then the turbo specifically would be good ideas. Hope that helps and Stay Tuned!

@@FlatironsTuning Thanks for the reply!!!! we shot some video troubleshooting the PCV and boost issue on my bugeye and will post that soon. But you're absolutely right. boost leak testing is a step-by-step process. there's just no way to shortcut it as thats what I tried and failed. I like the idea of vape testing but from my diesel experience sometimes they only leak under boost. Also, SHOUTOUT to you guys I bought some JDM tail lights from you online just before Xmas for my sons GC8 and they came in perfect I am sure will order more parts from ya'll JDM tail lights video below and again many many thanks kzfaq.info/get/bejne/iK1joMx52t2rf4E.html

Thanks for your question. It definitely is a tricky one. I believe that the Crawford AOS drained back to the turbo oil-return. But you are exactly right, You would have to make sure that the drain from the AOS didn't effect the turbos ability to drain. One of the more interesting we have seen recently is the Roger Clark Catch tank that drains to the oil pan drain bolt. It works for them because they are Right-hand drive. But we took an initial look, and it would be pretty darn hard to route a can from the right side all the way down to the drain plug. Still an interesting solution to the problem. If we come up with anything, we'll let you know!

FlatironsTuning interesting. There is an extra bung on a killer b pan. Long hose as you said.

@@FlatironsTuning I comments is quite inline with Davids. I would like to sum up the video pull out some conclusions and have your feedback about it: There are 3 circuits: * first equalizes pressures between crankcase and the head covers. * The second takes out "clean" blow-by-gasses (BBG) from head covers internal AOS outputs and connect directly to turbo inlet. * The third circuit connects to cranks-case AOS output (the more probable source of BBG), PCV valve, which output is turbo inlet hose and is triggered by a small line to intake manifold. When manifold is under pressure (WOT), it shuts the PCV valve. When manifold is under vacuum (no motor charge), valves open. I have five conclusions: * The three internal AOS work thanks to gravity and may not be effective for gasified oil (Blow-by-gazes). * Manifold under pressure (WOT): BGG from head covers enter the turbo inlet which is under heavy vacuum. * Manifold under vacuum (cruising): BGG from head-covers + crank-case enter the turbo inlet which is under light vacuum. * PCV valve function is only to limit the risk of allowing liquid oil from crank-case to enter directly into the turbo. * adding and external AOS will require to modify the plumbing of at least the 2nd and the 3rd circuits since oil return cannot be done to any internal AOS output (no oil should be there) Am i right ?

I don't think so. If you watch this video again, look at the white plastic connector that connects to the turbo inlet. In that white piece of plastic is a jumper connector that connects to the engine harness. Most likely, I'd guess that is not in place, and that is causing your CEL. I will also mention that on the newer cars, there are more of those jumper connectors. If any of those are not in place, then the car will throw a code for the PCV connection. I hope that helps and Stay Tuned!

That is a great question. Think of the PCV valve as a switch. It closes when the manifold is under pressure because you are using the vacuum pull from the turbo to scavenge the crankcase. But when you close the throttle and the turbo is no longer pulling that vacuum, the PCV valve opens, and then you are using the vacuum behind the throttle plate to scavenge the crankcase. I hope that helps, and Stay Tuned!

Thanks for watching!

Thanks for your question. I would answer that by saying that in the condition where the factory AOS system fails, the addition of something like the IAG AOS will give you more capacity. It is not a fix, just an increase in capacity. There is a little more to the cause of the issue, and we are working on a solution, or a discussion of possible solutions. I'd also recommend going through these videos as they go into more detail about what is going on when the PCV system fails: kzfaq.info/get/bejne/fqemq82EybfXiH0.html kzfaq.info/get/bejne/n7CjZLaEprW9mYk.html Hope that helps and Stay Tuned!

Thanks for your question. That is not a sensor actually. It is just a jumper electrical connection. Thanks for watching and Stay Tuned!

Thanks for your question. Putting on a catch can can certainly be a little tricky. If you haven't all ready, I'd recommend going through our video on AOS configuration here: kzfaq.info/get/bejne/bMiAmtad1b3OkZ8.html That might help you. The best piece of advice I would give is on a GD WRX or STI, you really need 2 catch cans to be able to plumb them correctly. I may actually be putting together a video on this topic here soon in fact. The one thing that you do not want to do is to "T" any of the lines into or out of the can. You need to keep both circuits separate (the one from the top of the factory AOS, and the other from the top of the valve covers). I hope that helps and Stay Tuned!

Sure. For track cars, there are definitely advantages to this. And if you are making a good deal of power ( say 400 - 450+ whp), then going to VTA again has some advantages. If you do, you just have to make sure that your plumbing is correct, that you have removed the PCV valve (as you mention), and that you are tuned for it. Hope that helps, and thanks for watching!

@@FlatironsTuning ​ FlatironsTuning I am in the middle of testing this out - I am getting some smoke on startup once routing all my hoses to a compact catch can. I did not get any smoke when just venting to the mini style breather filters you normally see on old V8 builds. I am thinking that running all the lines to a small catch can (reducing the size of the crankcase breather as well to fit) might be causing a restriction and causing some oil consumption? Is this a plausible theory? You can see the video about the PCV Delete I did on my channel under the subaru engine out video.

@@Booki89 The short answer is yes. If you look at the first Catch Can video I did, I "T'd" the intake and outlet on the catch can, and this is a mistake. Basically what we have now learned is that if you don't have sufficient breathing for the crank case, you will start to build positive pressure and this can prevent the turbo from draining properly. The smoke you are seeing on startup is most likely a symptom of that. I'd say you would definitely want to run 1 can per hose you are interupting. Or, if you are looking at VTA, that should also reduce the issue, but if you have a small single port that you are venting, that could cause an issue in an extreme case (running lots of boost pressure, making more than 400 whp, etc.). I hope that helps and good luck with the install!

@@FlatironsTuning Just thought I would update this post. Similar findings to yourself, I have the two valve covers T'D to my small catch can which VTA, and my crankcase is just with a breather filter for now (VTA) Smoke from start up is gone! There must have been a flow restriction to the can causing the pressure to build up as you said. Will need to mount up a separate can for the crank case vent.

@@Booki89 Glad that you are getting a handle on it, and that the fix was relatively simple :-) The PCV system is definitely more tricky than it would appear on the surface, and glad we could help!

I believe that fitting should be 1/2". Most of the PCV hoses are short of the main fitting that comes of the block which is 3/4". Hope that helps and Stay Tuned!

This one? www.flatironstuning.com/99071ab352-hose-vacuum Thanks for watching and Stay Tuned!

Thanks for the question Matthew. The simple answer is that yes, a PCV system's job is to control crankcase pressure, and also to get out all of the oil and fuel vapor that can collect in the crank case.

@@FlatironsTuning So then having a stuck pcv valve could be a very bad thing for the engine. Is that a fair statement? If so, then why don't manufacturers put those valves on a maintenance schedule? It seems like the kind of thing that could fail and lead you to drive around with too much pressure in your crankcase without even realizing it, jeopardizing seals and gaskets all over place. I'm just learning about these things -- the pcv system is fascinating I must say, and your video was very helpful conceptually even though I have the NA ej25. Planning to change it just for fun and see what the old one looks like when I take it out.

@@CommaCam Depending on how deep you dig, there is usually a replacement interval on a PVC valve. But on the newer cars, they do seem to be omitted on the maintenance schedule. The short answer to your question is yes, if the valve sticks, it can lead to excess oil consumption, and it is definitely something to check if you are having that issue. Thanks for your comment, and thanks for watching!

@@FlatironsTuning Thank you so much. Really appreciate your reply.

The reality is that the piston rings don't keep 100% of the gas expansion above them in the combustion chamber. So you get "blow by" - and as a motor gets more worn, this increases significantly. Those blow gasses have to go somewhere, else positive pressure build up will blow the crank seal out etc. The blow by is also rather noxious to breathe - so its most healthy destination for the environment and to stop burnt oil smells from the front engine area is for it to be feed back in with the intake fresh air, where it can be burnt. The PCV valve is just a one-way valve that sits at the final destination before entering the intake manifold. Unfortunately, oil finds its way into this flow of vapors. Especially if the PCV valve fails (happens at like 60k miles and up). The heat basically slowly melts the modern plastic ones.

Thanks for the question. In short, every system has its limits, and the same is the case for the stock PCV system. If you are seeing the signs that you need something like a catch-can or Air Oil Separator, then it is usually quite helpful. I hope that helps, and Stay Tuned!

Thanks for the question Jeremy. There are a couple of options. The best one being to duplicate the routing that the 2.5 liters got, and "T" that center breather to the valve covers. This would require adding an extra fitting the the valve covers themselves though. It is also a valid option to simply block that port off. In the early days of the hybrid swap, this was the preferred method. You just have to make sure that you aren't trapping oil in your heads which is what that new connection was designed to prevent. Keep in mind that for a daily driven car, balancing the pressure in the heads and crankcase is not very hard. It only starts to get interesting as you turn the boost/power up and especially when you start tracking the car. A third, somewhat new option would be to rout that fitting to incorporate it into an AOS system. I have talked to a couple of people about that and in a pinch, it might work okay. But the ideal would again be to duplicate the OEM routing. The one thing that you can not do is to rout it into your PCV system. There is a lot of liquid oil that comes up through that port, and if you connect that to your OEM PCV system, you start to see a good deal of oil consumption. I hope that helps, good luck with your project, and thanks for watching!

Some built ej205 blocks come with this port just blocked off, would it be harmful to run this system on a ej205 with 2.0 heads?

Glad it helped! Thanks for watching and Stay Tuned!

Thanks for your question. The first thing I would say is to make sure that your drain is routed properly to ensure that the AOS can is draining properly. Beyond that, we do have something in the works, but it isn't something that I can go into detail about yet. In the mean time, I'd recommend taking a look at these videos: kzfaq.info/get/bejne/n7CjZLaEprW9mYk.html kzfaq.info/get/bejne/pr6Bl8qprb2qp58.html Hope that helps and Stay Tuned for another video in the next couple of weeks.

@@FlatironsTuning thank you so much for the quick response! I’ll definitely stay tuned 👍🏼

Hello Booki. I just looked up a 2009 FXT, and it shows that the PCV valve itself is in a "T" that would be similar to the one that we discuss in this video. The catalog is not always 100% accurate though. If you need help finding a new valve, etc., please don't hesitate to reach out and we'll see what we can do. Thanks for watching!

FlatironsTuning thanks for the advice. Check out this video I just made. It looks like my pcv is in the intake manifold? kzfaq.info/get/bejne/fcV_gcx2qNvchJ8.html

Thanks for your question. Yes, you can install a catch can on an NA Subaru. Generally they would need them less, but the principal is the same. Just make sure that you follow the same rules and keep one can per PCV circuit. Hope that helps and Stay Tuned!

Thanks for watching. Stay Tuned!

Thanks for watching. The PCV valve needs to close when the intake manifold goes into positive pressure, which happens when a turbo starts making boost pressure. hope that helps and Stay Tuned!

@@FlatironsTuning thanks! Still confused 😆... so the pressure on the intake side before the compressor also becomes positive under boost conditions? I find that in itself confusing. I'd have thought it'd become more negative under boost as the turbo sucks in more air 🤔. I'd been theorizing that the pressure in the turbo intake might spike into positive under deceleration when the throttle body closes and the flow is suddenly blocked pushing pressure back past the turbo into the turbo intake duct.

@@fannerguitarworks1024 You are thinking correctly. There should be a slight vacuum in front of the turbo inlet, and the PCV system uses that vacuum to help scavenge the crankcase pressure. If you haven't watched it all ready, you should take a look at our video specifically on crankcase pressure. Here is a link to that: kzfaq.info/get/bejne/fqemq82EybfXiH0.html That might help since we are talking about some real world examples of modifications to the PCV system (AOS's specifically), and then how they effect crankcase pressure.

Thanks for your question Bill. I would say that for your car, the lack of oil consumption would mean that yes, your engine is healthy, and the stock system is working properly. If you are not going through oil, and you don't see enough oil in your intake system that would prompt you to correct that issue, you should be fine staying with the stock system. Hope that helps and thanks for watching!

So I've decided I want a catch can for my 06 WRX before installing a downpipe & tune. She's a daily driver and I want to maintain the longer oil change intervals, so I don't have to worry about possible oil contamination with an AOS. All the catch cans I've seen only connect to the tube (bolted to TMIC) that T's off to the valve covers... What about the other lines from the factory separator that connect to the turbo inlet and intake manifold? Wouldn't those have blow-by as well? I hope I'm understanding the system correctly. Your video focused on 3 main connections: - 1st is from crankcase to valve covers (not directly connected to intake air) - 2nd is from valve covers T'd to the turbo inlet - 3rd is from factory oil separator, one to turbo inlet and another to intake manifold. Am I correct? Wouldn't there need to be at least 2 connections to the catch can to collect all the blow-by?

Thanks for your question Bill. If you want to catch any and all oil that is going through the PCV system, you would need to look at both of the points where the system connects to the turbo inlet. The best piece of information I can give is that you want to keep both of those connections separate. If you want to use catch cans, you would need 2. You do not want 1 can with multiple connections in my opinion. This is the mistake that I made when starting to look at blow-by and hooking up a catch can that"T'd" both the inlet and outlets into one can. The reason for this is that those connections will function differently as the manifold goes from vacuum to pressure, and as the crank case starts to pressurize. If you connect them into one can, you are significantly limiting the systems ability to adapt to changing conditions in the manifold and case. This is something that we will dive more deeply into at some point, but that is the gist. Hope that helps, and thank you for watching!

I was going to use 1 can, but your recommendation has sent me in a different direction. It'll be much better to just install 2 cans connected to each inlet port, than to somehow connect multiple connections to 1 can. Thanks for the advice!! :)

No problem Bill. Glad we could help!

Thanks for your question. If you are going to change the configuration of your PCV system, you will have to tune the car for that change. I'd also say that there are definitely some benefits from having the PCV valve in place. I'd recommend that you take a look at the video that we did on the AOS/Catch-can configuration. That may be a good resource as well: kzfaq.info/get/bejne/bMiAmtad1b3OkZ8.html Hope that helps and Stay Tuned!

Thanks for your question. The short answer is yes. The newer STI's have a few more connections to the wiring harness, but the principal is the same. Thanks for watching and Stay Tuned!

Thanks for your question. You are correct, there are 2 points where the crankcase ventilation connects to the turbo inlet. Once from the valve covers to the turbo inlet (fitting closest to the front of the car), and one from the top of the factory AOS breather (fitting closest to the turbo). If you want to run a dual catch can, you would want to put one can on each of those circuits. I have actually put a set of dual catch cans on a car recently, so that is one of the topics that we have in the works. Thanks for watching and Stay Tuned!

@@FlatironsTuning is it incorrect where people use a single 3 port where the catch can out port goes only to the valve cover turbo inlet and the inlet from pcv is capped/plugged?

@@jonathancunanan I would say it is not ideal. We have played around with the configuration of various AOS and Catch-Cans, and the best advice I can give is that you want to keep the two circuits as intact as possible. If you join or "T" together the circuits in either the inlet, outlet, or both, some interesting problems can come about. We actually have a lot of content along these lines. Here are some good links that you may want to take a look at: kzfaq.info/get/bejne/fqemq82EybfXiH0.html kzfaq.info/get/bejne/rK2BmciizM-ViHk.html kzfaq.info/get/bejne/bMiAmtad1b3OkZ8.html Hope that helps!

@@FlatironsTuning it helps a lot. thanks!

Yes, that is fairly common actually.

Thanks for quick reply. May still have oil leak issue.valve covers done,now doing the oil cooler oil rings. Hope this helps. Last is the feed lines on the turbo

No fun! Hope you can track it down.

Thanks for your question. We definitely do, and we actually have kits built up for a lot of the common cars we work with. If you search for OEM PCV Hose Kit on our site, you will hopefully find what you are looking for: www.flatironstuning.com/catalogsearch/result/?q=oem%20pcv%20hose%20kit Thanks for watching, and thanks for your business!

@@FlatironsTuning I appreciate the information and the links. I have a V8 ej207 set of heads (chambered to run 2.5) and a JDM intake without TGVs. Do you know which one of the kits would suit me best? If I need to email or use live chat I will. Thanks in advance for your time!

@@nrw510 Definitely open up a live chat with us and we'll see what options we would have for you. Thanks!

Thanks for your question. Basically, any leak in the PCV system will translate into a vacuum leak to some degree. The bigger the leak, the bigger a problem that the leak can create. I would recommend that you smoke test the intake system, or take the car to a mechanic that can do that test for you. that will show you where the leak is coming from, and you should be able to get a measure of how significant the leak is as well. On Mass Airflow cars, it is quite important to keep any intake leaks to as near zero as possible. I hope that helps, and Stay Tuned!

Thanks for your question, if you have that additional breather on each head, then yes, that should be the same. Hope that helps, and Stay Tuned!

Thanks for your question. Because the hose from the valve covers (the metal tube on the intercooler) connects to the front of the turbo inlet hose, there is not much suction there. In most cases, this is actually a fresh air feed for the crankcase because the vacuum occurs at the back port with is the top of the factory AOS. In short, that would typically be the port that you would see the most oil coming out of initially. It is worth mentioning that if you are overloading your PCV system, that is when you would see oil coming out of the valve covers, and that would indicate a greater need to modify the system. I hope that helps, and Stay Tuned!

Thanks for your question. We actually have several PCV hose kits on our web-site. Here is the link to that: www.flatironstuning.com If you don't find what you are looking for, reach out to us through Live Chat and we'll do our best to help. Thanks for watching and Stay Tuned!

Thanks for your question. It really depends on how much oil you are seeing move through your PCV system. If you are not losing much oil, a catch can is much simpler, so that may be the best solution. If you are seeing more oil move through the PCV, (say half a quart in a day at the track), then an AOS may be a better solution. I hope this helps and Stay Tuned!

At that point, the line being described is the line from the metal hard line that goes forward to the turbo inlet. If that is the correct one, this is what vents the valve covers to the turbo inlet. If that is cracked or becomes dislodged, the main issue would be that you now have a large vacuum leak that is letting in a lot of unmetered air. This can definitely cause some drivability issues, and a lean-running condition. I hope that helps and thanks for watching!

Thanks for your question. The simple answer to that question is that it depends on your oil consumption. The degree to which you need something like a catch can is entirely dependent on how much oil, if any, is moving through your PCV system. This will vary depending on how you drive, the amount of power that you make, the build of your engine, etc. So keep track of your oil consumption and that will answer your question. If you aren't using much oil if any, then your need for something like a catch can is minimal. I hope that helps, and Stay Tuned!

Thanks for your question. If you are using that case in an NA251, you would simply block off that center port. You don't need it, and you wouldn't have anything to connect it to so you are best to just cap it off. Thanks for the question and Stay Tuned!

Thank you. The cross over pipe actually wouldn’t allow to just cap so I had to commit to plugging it, and then I cut the plug bolt and shaved it smooth with the case. Came out really well and just glad to verify everything. Thank you.

Thanks Osvaldo. Actually, the 2.0 is basically the same layout as we describe here, but it doesn't have the 2nd port on the valve covers. that second port connects the left and right valve cover to the center crank-case. But if you remove that, everything else is basically the same. I hope that helps, and thanks for watching!

Thanks for your question. That white connector connects to the manifold wiring harness. It is basically just a jumper to tell the ECU that the PCV system is connected. Hope that helps, and thanks for watching!

Thanks for your question. First, keep in mind that the PCV valve is only open when the intake manifold is in vacuum. Once it goes positive, the valve closes. And yes, sealing that off, and venting to atmosphere is an option. I'd recommend that you take a look at the video we did about AOS configuration, as we go into that in a bit more detail, and there is more to come on the subject: kzfaq.info/get/bejne/bMiAmtad1b3OkZ8.html Thanks for watching!

FlatironsTuning thanks for the reply! Do you think it could cause any smoke issues on startup due to inadequate vacuum? (Eg if you ran them all to one compact catch can)

The short answer is yes. This is at least in part why we got the results we did when we started testing a catch-can for our AOS vs. Catch Can testing. Here are links to those vids. What ever you do, don't hook up a catch can like this :-) More to come on this, but this is a start: kzfaq.info/get/bejne/rtB2jLpirqnOeaM.html kzfaq.info/get/bejne/npNmqrGhm9iZZGw.html

FlatironsTuning I understood from your videos your cars Catch can overfilled and as you stated if caused it to smoke alot due to it all being sucked into the intake. I have my pcv blocked off and currently just running some breather filters on my crankcase and valve cover ports...do you think this could cause my car to smoke on cold starts ?

You have to look at your crank-case pressure. If your breather system is not letting pressure dissipate when under high load/full boost, this can prevent the turbo from draining properly. If this happens, then that can cause smoke on start-up because oil is being forced out either the compressor or turbine housing. Usually you would see signs of leaks from either the turbo drain hose, or other PCV hoses too. But what we have now learned is that insufficient venting can cause exactly that.

Thanks for your question Marco. Believe me, we are working on it. If you watch the videos that we have made about the Catch-Can vs. AOS, we start going into this. We should have some more good information here soon. Thanks for watching!

FlatironsTuning thank you I'll be definetly looking forward your findings as to me the pcv delete isnt the way to go at least not as simple as that

Just to make sure I'm understanding correctly, are you just looking to remove the PCV valve itself? Or to replace the entire plumbing of the PCV system?

Thanks for your question! Someone has asked about a stumble kit, so we will add that to our list :-)

Thanks for your question. Basically, if you are not moving oil/crank-case gasses through the inlet of the engine, the need for a catch can or AOS is very minimal. If your car is stock, and it is daily driven, then you are probably fine leaving everything stock. The two tell-tale signs are needing to look at changing something would be needing to add oil between change intervals (of say 3,000 miles or more, and needing to add more than 1/4 to 1/2 of a quart), and signs of oil in your intercooler that is more than a very small film. If you haven't looked at it all ready, I would also recommend looking at the video we did comparing the difference between an AOS and Catch Can as well, as that may be some good information for you too: kzfaq.info/get/bejne/pqdjjMl-zNXKonk.html Hope that helps, and thanks for watching!

The short answer is no. You do not want to "T" either the feed side, or return side of any of these hoses. It will cause issues. This is something that we are going to go into detail about here soon as well. If you are going to install a catch can, you want to keep the PCV circuits completely separate. Hope that helps and Stay Tuned!

Thanks for your question. I'm not familiar with that code. I would recommend checking the white harness where the PCV hose connects to the turbo inlet. There is a jumper there that clips into a wiring harness, and that may be missing. That would be my best guess as to what would throw that code. Hope that helps, and Stay Tuned!

Thanks for watching!

Absolutely! Thanks for watching and Stay Tuned!

Thanks for your question Justin. The cooling systems on Subaru's tend to be pretty over-built. The issue you are describing is most likely caused by "lifting" a head from high boost pressure. This would relate to a compromised head stud as well. This is something that shouldn't be much of an issue with a proper build, but I can see where it could come up. I'll add this to our working list:-) Thanks Justin.

i had done a full re build on my ej25 with arp head studs darton dry sleeve included an machine the heads an block for flatness an still the coolant get into the over flow bottle this has been the 3 time i remove the motor to correct this problem an now 3k miles on the build an 20lbs of boost an still we having this problem with coolant over flowing n a few bubbles

took it too the track yesterday an when i parked to have it cool off i notice a few bubbles not much nor have the level pass full mark on the bottle yet but i have seen this b4

also the part where i bleed the system is done with a vacuum bleeder tool. car has no heater system has upgraded radiators an fan! both me an my friend have this problem when pushing the car hard! cars only making around 380 to the wheels!

i am leading toward a thermostat removal as it seems the cooling system are a bit weak! but i dont know need help car was running fine still is but when pushing boost its then i would see some bubbles. replaced rad caps you name it done everything that i would know how to do to fixs this problem. so i was leaning towards removal of thermostat b4 anything gets bad

Thanks for your question. I'd definitely recommend replacing any old lines, etc., in the PCV system, and then keep an eye on your oil consumption once the car is running. If you are using any oil, or you see signs that you are moving oil through the PCV system, then you would want to put in a catch can or AOS depending on the oil volume. Hope that helps, and good luck with the build. Stay Tuned!

Hello Tristan. Thanks for your question. That depends on how you want to deal with the additional center crankcase vent that the 2.5 liter block has that the EJ20 doesn't. One option is to simply cap that extra breather off. The other option (and most likely the best option) is to add extra fittings to each of your EJ20 valve covers and duplicate the routing that the EJ25's got on your hybrid. The only think you should not do is run that extra breather into your PCV system. That will result in excessive oil consumption. I hope that helps, and good luck with your build!

Saw this after posting my comment today. My valve covers are already back on the engine and I have a date with the dyno so I don't have time to take them off right now. I'm safe to just plug this port for now if I read this correctly? No AVCS and stock clearances inside the engine.

Thanks for your question Greg. It all comes down to oil consumption. If you are not using any oil, or just a minimal amount between changes, most likely you are okay leaving it stock, or a small catch can, etc. The key is to keep an eye on it, and watch out for something that changes over time. This is a topic that we go into more detail in other videos about, but always feel free to reach out to us directly if you have more questions. Thanks for watching!

I have an Ej255 that consumes about 1qt every 3 to 4 thousand miles. I'm told this is pretty minimal and not to be concerned.

Thanks for the question Jon. Yes, I'd say that if you are just using/losing that quart over 4,000 miles or so, that would definitely be in a normal range.

deon yang Honestly, VTA is the best way. But you know, it causes harm to the environment

Retrospeck yet people remove cats left and right which is 10x worse.

That is certainly possible, especially as the hoses get older. If the hose has turned solid, there is a good chance that it is not sealing properly any longer. Thanks for watching and Stay Tuned!