Valve Cover breather with MAFT setup

[ScreamSalvation]

Ok, I've searched and read on the PCV system but haven't seen in definate answers for someone running a MAFT setup.

I know stock that the VC breather is hooked up pre turbo so it seems vacuum but never boost, correct? The PCV valve opens under vacuum but closes during boost, you would still be pulling out fumes through the VC breather.

Right now as some of you know I have been putting my eclipse back together from the PO and his mistakes. There is currently just a filter on the VC breather and the PCV valve is still hooked up. The car is also setup with a MAFT system on it.

I know the best way to hookup the VC breather would be after the MAF so that only metered air is allowed in, but being a MAFT setup that only leaves me hooking the breather to the intake manifold. This would allow the breather to see the necessary vacuum but also it would receive boost, thus possibley overpressurizing the VC, correct?

I guess it comes down to, with a MAFT, would the best setup be to connect the VC breather pre turbo again even with unmetered air and then richen the fuel mixture to account for this?

I plan on adding a filter or catch can to the PCV system and a check valve.

DSM link is hopefully in my future for tuning, but not this paycheck

 

[No_Skillz]

This is one of the drawbacks of the MAFT setup - you cannot use the factory circulation system for the crank case. You could do it like you said but it will be hard to tune for. You could also install a checkvalve and connect the VC nipple after the MAFT. It won't circulate under pressure but will still maintain proper function at all other times.

 

[92AWDHX40]

Yes ^he's right.

 

[ScreamSalvation]

That's what I needed to know. I was wondering if a check valve would allow it to circulate under vacuum but not boost.

Would a check valve from US plastics such as these work?

Check Valves - US Plastic Corporation [www_usplastic_com]

shortened url since the other was too long to post apparently.

I am planning on adding a filter onto the line also, but with a filter and check valve connecting to an intake nipple should be fine?

 

[obx tsi]

I am also curious about this. I have a breather on the valve cover and have left the other line that attached pre turbo just open. Would like to know what others with a maft setup do.

 

[HBWaterfowler]

Why would the MAFT have anything to do with the crankcase ventilation?

I would think it would be the same as stock or MAFT/other???

 

[slowstang]

Why would the MAFT have anything to do with the crankcase ventilation?

I would think it would be the same as stock or MAFT/other???

Because the stock setup draws air pre-turbo but after the MAF, keeping the VC out of boost but allowing the air to be metered for tuning. When the intake manifold is under vacuum it draws air through the PCV valve which get it's air from the side VC vent. If that vent isn't hooked up after the air metering device, theres a discrepancy in tuning.

However all that being said, all of my friends using MAF-T just throw a filter on that VC breather and tune like it's not a problem.

 

[1992awdlaser]

This is why I have my catch can set up the way I do.

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[TSIMonsteR]

In all honesty, it should still be fine hooking the VC to the intake pre-turbo even though the MAF is going to recount this air, right? Is it really going to be so much air that its going to make it harder to tune?

I guess the simple solution is just a VC breather, but this doesn't provide vacuum to really get the air out.

hmmm....

 

[TSIMonsteR]

This is why I have my catch can set up the way I do.

What is the point in having the PCV at all in this setup? There would be no vacuum at any point to pull the air. This would be no different than putting a breather on both really...?

 

[1992awdlaser]

^^I am sorry but that is just flat out ghetto. I am assuming you guys have no tech inspect your car before going to the track?

Better to do it for free rather than spend $70 on a catch can at this point in the modding process imo.

This should pass tech inspection at any track really. It works exactly the same as a catch can and is secure.

 

[1992awdlaser]

What is the point in having the PCV at all in this setup? There would be no vacuum at any point to pull the air. This would be no different than putting a breather on both really...?

You would be correct. That is why it is drilled out.

Edit: There doesn't have to be a vacuum since the crankcase is pressurized. The air comes out by itself because of the pressure.

 

[1992awdlaser]

Pressure comes from the piston moving down. The whole reason for "vents" are to get rid of crankcase pressure. PCV=POSITIVE crankcase ventilation. Positive meaning pressure.

How is it going to get hot where it is? That is what I would say if a tech guy said that to me. And then they would just stand there because nothing is even close to it that puts off enough heat to melt it.

 

[HBWaterfowler]

The VC breather is a in/out?
PCV is a one way valve (in?) under boost?

I don't see the harm in having just a filter on the VC breather and keeping the PCV stock.

Like someone was saying, you don't need to have the VC breather hooked up. The air will get blown out as needed. If you are worried about the air not getting metered correctly, I would say, that the air lost is so little that it would have no effect for tuning.

Right?

 

[obx tsi]

Thanks for the pictures 1992awdlaser. That is what I am looking for is just how people have their maft setup. I could care less about all the reasons and technical discussion right now. So anyone else with a maft setup please post pictures and or description of what you have done with your vc line and such. Thanks.

 

[TSIMonsteR]

You would be correct. That is why it is drilled out.

Edit: There doesn't have to be a vacuum since the crankcase is pressurized. The air comes out by itself because of the pressure.

Cool. So this works well for you then?

Actually seems like a good idea. Brilliant really. You solve the problem of boost entering through the PCV while also keeping both "vent" ports open at all times.

Thanks for the idea. I'll set mine up this way this weekend.

 

[1992awdlaser]

Doesn't a PCV valve keep positive pressure(we know they leak) from entering the crank? Again correct me if I am wrong but the valve closes under pressure to keep the positive pressure from entering the valve cover and going to the crank which leads to the dipstick popping out if the valve fails? To my understanding the whole point of the vent is to help with emissions and to help keep your oil form getting contaminated with unburnt fuel resulting in frequent oil changes. Yes this may not matter for a track car but on a daily driver I would want my oil to last as long as possible.

The way the stock system is set up, you will be getting oil in the entire intake system. This can get into the cylinders. It will build up a film on the inside of the majority of the intake system. With a catch can, you CATCH this oil instead of it going into useless places. If you want it is perfectly safe to put the oil back in the engine from the catch can.

 

[1992awdlaser]

Cool. So this works well for you then?

Actually seems like a good idea. Brilliant really. You solve the problem of boost entering through the PCV while also keeping both "vent" ports open at all times.

Thanks for the idea. I'll set mine up this way this weekend.

Yes, it works perfect. You can do it with a regular catch can or how I did. Make sure you drill some small holes in the top portion of the bottle for the crankcase air to get out of. Or if using a catch can make sure you have a breather on top of it. You do not want a sealed one with it set up this way.

 

[bpk1337]

Yes, it works perfect. You can do it with a regular catch can or how I did. Make sure you drill some small holes in the top portion of the bottle for the crankcase air to get out of. Or if using a catch can make sure you have a breather on top of it. You do not want a sealed one with it set up this way.

Do you have any more pictures of that? looks intresting. haha i dont have the money for an oil catch can this might be a good temporary solution.

 

[1992awdlaser]

Do you have any more pictures of that? looks intresting. haha i dont have the money for an oil catch can this might be a good temporary solution.

No more. It's pretty simple. Just two lines off the valve cover going to a vacuum t. Then the one line goes into the bottle's cap. Drill a hole in the bottle's cap for it to go in. And drill some small holes near the top part of the bottle. And drill out the pcv so it is open ll the time.

 

[bpk1337]

No more. It's pretty simple. Just two lines off the valve cover going to a vacuum t. Then the one line goes into the bottle's cap. Drill a hole in the bottle's cap for it to go in. And drill some small holes near the top part of the bottle. And drill out the pcv so it is open ll the time.

ooohh i see. where does the other line go? back to the intake or..?

 

[JayRolla]

Better to do it for free rather than spend $70 on a catch can at this point in the modding process imo.

This should pass tech inspection at any track really. It works exactly the same as a catch can and is secure.

Actually I just bought an ebay catch can for under $20 and installed it just like you. I originally had the pcv valve and VC breather straight into the catch can but with no way to breath. I then went and bought a tee like you.

Here is the one I got but mine is chrome.

eBay Motors: Oil Catch Reservoir Can Tank Talon Eclipse Mirage Blue (item 120333207020 end time Nov-19-08 17:55:24 PST)

 

[JayRolla]

No more. It's pretty simple. Just two lines off the valve cover going to a vacuum t. Then the one line goes into the bottle's cap. Drill a hole in the bottle's cap for it to go in. And drill some small holes near the top part of the bottle. And drill out the pcv so it is open ll the time.

You can plug the VC if you do it this way.

 

[1992awdlaser]

ooohh i see. where does the other line go? back to the intake or..?

The two connect and then the one just goes into the bottle.

You can plug the VC if you do it this way.

What do you mean?

 

[JayRolla]

Ive seen people completely plug up the Valve Cover breather and just drill through the pcv valve and only vent that. Seemed to work fine.