Another PCV thread

[AWCR1MC]

I’ve read through every possible PCV thread on here and other forums, but still can’t figure out this stupid system. I’m about ready to do an LS swap and say fuck the n54.

Under the advice of VTT, I went with their dual catch can setup after getting their VC. I’ve been getting the 2d2e code ever since running the throttle body PCV adapter. I switched to venting both sides to atmosphere to see if I would stop throwing that code. It did, but then the problem turned into smoking at idle on the high and low side.

I returned it back to how it was, but am still getting smoke at idle from the high side which is VTA. It never smoked like this before, so I’m confused as to why it’s changed all of a sudden???

Maybe the throttle body adapter or check valve is faulty?

I did a compression check to make sure the motor is healthy. I got 180 across the board, so I was happy to see that at least

Someone mentioned to me that I should be running a -8 check valve in-line before the low side catch can, and then get a vacuum relief valve as well.

Does anyone else have any input or advice on this?

 

[doublespaces]

If you want to retain the PCV function, you are in for a world of complication.
Do you have the PCV head ports plugged?


Which part of this diagram do you deviate from?

 

[AWCR1MC]

If you want to retain the PCV function, you are in for a world of complication.
Do you have the PCV head ports plugged?


Which part of this diagram do you deviate from?
View attachment 54819

Yes I have my head ports plugged. Only thing I’m missing the vacuum relief and the -10 in-line check valve. I’ll be getting the vacuum relief and in-line check valve this week. I have a breather, but it kept getting stuck, so I took it off. I’ve been told the in-line check valve should be on the -8 line and not the -10?

 

[doublespaces]

Yes I have my head ports plugged. Only thing I’m missing the vacuum relief and the -10 in-line check valve. I’ll be getting the vacuum relief and in-line check valve this week. I have a breather, but it kept getting stuck, so I took it off. I’ve been told the in-line check valve should be on the -8 line and not the -10?

So first of all, the -10 check valve is borderline optional, it depends on how restrictive the filter and catch can is on that same line, so it's luck of the draw in a way whether or not you need it and the associated relief.

It could be too free flowing or not free flowing enough and you'll get a throttle blade code because the car has to adjust outside of it's accepted range while trying to keep the idle in the right spot.

Normally there is a flapper valve there which has a metered orifice, it controls how much air can flow inward into the valve cover during idle. Since there is no check valve it all falls on your filter and your catch can construction to place the correct restriction, which it sounds like it does not. Since vacuum varies from one car to another, people can get different results here even with the same pcv setup.

By adding the -10 check valve, this cuts off that path during idle which eliminates that variable and instead you are expected to open up a new path via the vacuum relief. This relief can be adjusted in a way that your car can be happy in a controllable manner.

As for why you're getting smoke from that filter at idle, the only explanation I can think of is you're now getting enough positive crank case pressure/blowby for some reason and it isn't completely being sucked in through the throttle body port. The excess is coming out the -10 line. Once you change these things, it may take a little while for your adaptations to revert back to their original state. Just a guess.

When you say you vented both ports to the atmosphere, what did you do with the throttle body port?

 

[AWCR1MC]

So first of all, the -10 check valve is borderline optional, it depends on how restrictive the filter and catch can is on that same line, so it's luck of the draw in a way whether or not you need it and the associated relief.

It could be too free flowing or not free flowing enough and you'll get a throttle blade code because the car has to adjust outside of it's accepted range while trying to keep the idle in the right spot.

Normally there is a flapper valve there which has a metered orifice, it controls how much air can flow inward into the valve cover during idle. Since there is no check valve it all falls on your filter and your catch can construction to place the correct restriction, which it sounds like it does not. Since vacuum varies from one car to another, people can get different results here even with the same pcv setup.

By adding the -10 check valve, this cuts off that path during idle which eliminates that variable and instead you are expected to open up a new path via the vacuum relief. This relief can be adjusted in a way that your car can be happy in a controllable manner.

As for why you're getting smoke from that filter at idle, the only explanation I can think of is you're now getting enough positive crank case pressure/blowby for some reason and it isn't completely being sucked in through the throttle body port. The excess is coming out the -10 line. Once you change these things, it may take a little while for your adaptations to revert back to their original state. Just a guess.

When you say you vented both ports to the atmosphere, what did you do with the throttle body port?

Ok makes complete sense, thanks for the explanation.

I took the whole car about and put everything g back together after checking things out. I think my check valve got flipped around, because when I drove it again after putting it together the smoke is gone. I’ll still probably add the in-line check valve just in case.

When I ran VTA on both it just had a filter on the front of each can. I only ran it like that for a little bit to see if it would stop the 2d2e code. I returned it back to how it was originally and things are ok outside of rhe 2d2e code.

So I should only run the in-line check valve on the -10 high side and not the -8 on the low side? It seems like once I add the vacuum relief and check valve I should be good to go.

 

[doublespaces]

Ok makes complete sense, thanks for the explanation.

I took the whole car about and put everything g back together after checking things out. I think my check valve got flipped around, because when I drove it again after putting it together the smoke is gone. I’ll still probably add the in-line check valve just in case.

When I ran VTA on both it just had a filter on the front of each can. I only ran it like that for a little bit to see if it would stop the 2d2e code. I returned it back to how it was originally and things are ok outside of rhe 2d2e code.

So I should only run the in-line check valve on the -10 high side and not the -8 on the low side? It seems like once I add the vacuum relief and check valve I should be good to go.

You need the -8 check valve. If you don't have that you'll be sending boost into the crank case. This will potentially result in you spraying caught oil out of your -10 filter(high side). In other words you'd have a massive boost leak. You have that check valve installed currently correct?

And remember if you install that -10 check valve, the relief becomes mandatory because it's not a metered check valve like the flapper. It's a full stop one way valve. Your car will idle poorly or die and your crank seal will probably start howling.

 

[AWCR1MC]

You need the -8 check valve. If you don't have that you'll be sending boost into the crank case. This will potentially result in you spraying caught oil out of your -10 filter(high side). In other words you'd have a massive boost leak. You have that check valve installed currently correct?

And remember if you install that -10 check valve, the relief becomes mandatory because it's not a metered check valve like the flapper. It's a full stop one way valve. Your car will idle poorly or die and your crank seal will probably start howling.

I was referring to an in-line check valve between the VC and catch can inlet. Only asking because it was suggested to me……after reading your explanation it doesn’t make sense to have two different valves on the same line.

Having a -10 check valve would mean I have a sealed system, which is why the vacuum relief would be the crucial. If I didn’t do the check valve but had it VTA it would be almost the same thing as a vacuum relief just not one that could be adjusted.