Smoking from high side PCV after ports plug.

[Traf]

Hi guys, i have a small problem regarding my PCV system.

My high side PCV is catch can then VTA.
My low side was stock until i plugged the 6 holes in the head and did a external low side PCV 2 days ago.

My problem is now i get a lot of smoke coming from the VTA high side at idle/low loads, meaning the crank case is under pressure.
Somehow plugging the ports and routing the low side externaly lowered the crank case vacuum...

I really don't understand what is happening, if someone has any idea it would be really appreciated.

 

[doublespaces]

Hi guys, i have a small problem regarding my PCV system.

My high side PCV is catch can then VTA.
My low side was stock until i plugged the 6 holes in the head and did a external low side PCV 2 days ago.

My problem is now i get a lot of smoke coming from the VTA high side at idle/low loads, meaning the crank case is under pressure.
Somehow plugging the ports and routing the low side externaly lowered the crank case vacuum...

I really don't understand what is happening, if someone has any idea it would be really appreciated.

Assuming your plumbing is done correctly, it could mean you have some blowby issues, ringland possibly? At idle crank case gasses should be evacuated from the low side into the intake manifold into the engine. Are you sure that is setup correctly?

 

[JimboFresh206]

So you blocked the ports and haven't added a low side+pcv.

If so seems normal..

 

[doublespaces]

So you blocked the ports and haven't added a high side+pcv?

If so seems normal..

If I am understanding he said he added an external pcv valve on the low side. The high side literally needs nothing to function. You can rip the flapper off and just drip oil out and the car will run fine. Some cars might like having a restrictor but that doesn't have any bearing on why smoke is exiting that port at idle, with a properly plumbed PCV system.

 

[Traf]

Assuming your plumbing is done correctly, it could mean you have some blowby issues, ringland possibly? At idle crank case gasses should be evacuated from the low side into the intake manifold into the engine. Are you sure that is setup correctly?

Well plumbing isnt that complex, TB adapter >> Catch can >> Checkvalve on the VC. I measured vacuum going to the check valve i got -10.1Psi.
I thought about the ringlands, but that wouldn't explain why the problem wasn't there before. Also the amount is minimal, just enough to see it.

 

[JimboFresh206]

What's the weather like there?

It's cooling off and getting moist here and my catch can (vta only to inlet) filled up pretty quick with moisture and fuel vapor gross stuff.


@doublespaces typo there made that pretty confusing lol, I read his post as just a vta and no low side. Aka no vaccum and blow by/vapors at idle, which would be expected. Lol sorry about that

 

[doublespaces]

Well plumbing isnt that complex, TB adapter >> Catch can >> Checkvalve on the VC. I measured vacuum going to the check valve i got -10.1Psi.
I thought about the ringlands, but that wouldn't explain why the problem wasn't there before. Also the amount is minimal, just enough to see it.

If there is vacuum in your intake manifold then we pretty much know the crank case pressure is coming from the combustion chamber.

The "Because it worked before" reasoning is never good reasoning, it is simply what we often resort to when there is no other explanation. When I read the situation as you've explained it, you're saying the engine is able to evacuate the crank case pressure through the head ports better than through the external PCV valve.

So either the PCV valve and related pathway to the crank case is under performing or the amount of crank case pressure being generated by your engine is greater than normal. If there are other options then feel free to chime in, this is just the first thoughts that come to mind.

EDIT: If I were to guess at 10 PSI of vacuum, the engine can probably displace a larger volume of air through the six head ports and associated pathways in the valve cover than can be drawn through the single PCV valve at the same vacuum level. If I recall, that hole really isn't very large. So assuming everything is plumbed correctly, we have zero reason to believe any changes you've made are somehow causing your engine to blow smoke. Viewing the situation that way is why this seems confusing. As sucky as it would be for this to be true, I find it more plausible that it simply smokes more than normal but the stock system is capable of hiding it better.

I have seen many reports of people switching to a VTA Breather and blamed the system for causing all kinds of smoking problems. The reality is the smoking problem already existed but the engine wasn't ingesting and covering it up..

Perhaps it is time for you to do a leakdown test?

 

[Traf]

What's the weather like there?

It's cooling off and getting moist here and my catch can (vta only to inlet) filled up pretty quick with moisture and fuel vapor gross stuff.


@doublespaces typo there made that pretty confusing lol, I read his post as just a vta and no low side. Aka no vaccum and blow by/vapors at idle, which would be expected. Lol sorry about that

It was a pretty sunny and dry day when i first drove it after the modification.

If there is vacuum in your intake manifold then we pretty much know the crank case pressure is coming from the combustion chamber.

The "Because it worked before" reasoning is never good reasoning, it is simply what we often resort to when there is no other explanation. When I read the situation as you've explained it, you're saying the engine is able to evacuate the crank case pressure through the head ports better than through the external PCV valve.

So either the PCV valve and related pathway to the crank case is under performing or the amount of crank case pressure being generated by your engine is greater than normal. If there are other options then feel free to chime in, this is just the first thoughts that come to mind.

EDIT: If I were to guess at 10 PSI of vacuum, the engine can probably displace a larger volume of air through the six head ports and associated pathways in the valve cover than can be drawn through the single PCV valve at the same vacuum level. If I recall, that hole really isn't very large. So assuming everything is plumbed correctly, we have zero reason to believe any changes you've made are somehow causing your engine to blow smoke. Viewing the situation that way is why this seems confusion. As sucky as it would be for this to be true, I find it more plausible that it simply smokes more than normal but the stock system is capable of hiding it better.

I have seen many reports of people switching to a VTA Breather and blamed the system for causing all kinds of smoking problems. The reality is the smoking problem already existed but the engine wasn't ingesting and covering it up..

Perhaps it is time for you to do a leakdown test?

Well i agree with you that the 6 holes in the head would draw more than the external routing, the thing is, the pathway to the 6 holes also goes through the PCV valve and thus is restricted.
Anothing thing i noticed, is that there is less smoke when i pinch the hose going to the PCV valve. So when i supress the vacuum there is less smoke which is really counter intuitive...

 

[The Convert]

1. How did you measure crankcase vacuum?

2. Do you have the low side pcv valve in correctly?

 

[Traf]

1. How did you measure crankcase vacuum?

2. Do you have the low side pcv valve in correctly?

I didn't measure the crankcase vacuum, i measured the vacuum going to the pcv valve.

Well i think i do, its an adaptater i bought so idk rly. My next step was to test by ditching the PCV valve and somehow connecting the hose directly to the VC . Just to see if the valve is causing this.

 

[doublespaces]

I didn't measure the crankcase vacuum, i measured the vacuum going to the pcv valve.

Well i think i do, its an adaptater i bought so idk rly. My next step was to ditch the test by ditching the PCV valve and connecting the hose directly to the VC somehow. Just to see if the valve is causing this.

If we are going back to a plumbing issue then I would immediately suspect the valve. Measure the vacuum on the crank case side of the valve or try blowing through it to make sure it is working and not backwards.

You could connect directly but do not drive the car this way obviously as that test only works while idling.

 

[Traf]

If we are going back to a plumbing issue then I would immediately suspect the valve. Measure the vacuum on the crank case side of the valve or try blowing through it to make sure it is working and not backwards.

You could connect directly but do not drive the car this way obviously as that test only works while idling.

Of course it would be just to test at idle, won't drive the car without the PCV valve.

 

[doublespaces]

Of course it would be just to test at idle, won't drive the car without the PCV valve.

If you decide you are 100% fed up with the car however, I am interested in a video of that.

 

[Traf]

If you decide you are 100% fed up with the car however, I am interested in a video of that.

Well actually you could drive it if you don't go into boost right ?

 

[The Convert]

You can pull too much vacuum and damage seals, then hydro lock the engine through sucked oil with the low side pcv replaced. It happened to a buddy of mine.

Cc Vacuum should be measured from oil cap with the bmw tool. It’s only like $90 and is great for this kind of diagnoses. You just need a gauge that also reads vacuum.

 

[doublespaces]

You can pull too much vacuum and damage seals, then hydro lock the engine through sucked oil with the low side pcv replaced. It happened to a buddy of mine.

Cc Vacuum should be measured from oil cap with the bmw tool. It’s only like $90 and is great for this kind of diagnoses. You just need a gauge that also reads vacuum.

When people say the the seals are howling etc, which seals exactly? That has never happened to me so I don't know first hand what is going on for sure.

Well actually you could drive it if you don't go into boost right ?

Seems fine however if you did try to go into boost your wastegate duty cycle would probably shoot way up and you may squirt oil out of your high side catch can into your engine bay by pressurizing it. Also your low side catch can might push oil into the crank case in reverse, but this would probably be minimal if at all. Basically it would be a massive boost leak and perhaps some other side-effects I am nothing thinking of.

 

[Traf]

You can pull too much vacuum and damage seals, then hydro lock the engine through sucked oil with the low side pcv replaced. It happened to a buddy of mine.

Cc Vacuum should be measured from oil cap with the bmw tool. It’s only like $90 and is great for this kind of diagnoses. You just need a gauge that also reads vacuum.

I was looking for a tool like that ! Do you have a link or a PN?

 

[The Convert]

I was looking for a tool like that ! Do you have a link or a PN?

I think I got mine from ecs tuning. I’ll try to remember to see if it has a pn on it.

 

[Traf]

I think I got mine from ecs tuning. I’ll try to remember to see if it has a pn on it.

I think i found it, thanks
https://www.ecstuning.com/b-genuine-bmw-parts/pressure-test-adaptor/83300496326/

 

[The Convert]

I think i found it, thanks
https://www.ecstuning.com/b-genuine-bmw-parts/pressure-test-adaptor/83300496326/

That’s the one.