CSL breather tube

[repoman89]

For the system to function correctly, you need variable control over the position of the PCV. That's why it's an electrically-actuated valve in the first place, and it's why earlier cars didn't just tee the oil separator outlet to the airbox and vacuum at the air rail.

If you're on a CSL tune, it's not aware that the PCV is even there, so my bet is if the car runs normally, then terra's hypothesis is right: The harness is probably powered by default such that even if the ECU isn't aware of the valve, turning the car on snaps the valve shut and keeps it that way. Then the system functions as if it were an earlier car (e.g. a CSL) having its oil separator connected only to the airbox. I'd love to test that but my cars are '01 and '02, so I don't own a PCV-capable wiring harness.

You can probe it in the DME box if you can manage to stick a multimeter lead to pin 52 of X60003 while it’s plugged in (can’t remember if that would be possible). Other end is one of the big Molex connectors in there looks like. I snipped off my breather valve connector and need to remember to pull these two wires one of these days.

https://www.newtis.info/tisv2/a/en/e46-m3-cou_200506/wiring-functional-info/power-train/engine-control/digital-motor-electronics/controller/crankcase-ventilation-valve/uHDGNAK

[Cubieman]

Wonder if I could back probe that connection, I'll check. Hopefully I'll have my airbox installed by Sunday is the goal.
If I can back probe the connection I'll test stock than test again after installed CSL DME.

[ethan]

But to answer your question, I think we're getting pretty close to the definitive answer, no?

Isn't the idle air valve (which is variable and PWM-controlled) going to compensate for the air coming from the PCV? It can compensate within reason, and this would be within reason.

All of the air mass will be calculated by the MAP sensor and IAT sensor, I believe. I think the DME looks at RPM targets to main idle with the correct fueling. This is my grossly oversimplified understanding/mis-understanding of course - feel free to correct.

For the system to function correctly, you need variable control over the position of the PCV. That's why it's an electrically-actuated valve in the first place, and it's why earlier cars didn't just tee the oil separator outlet to the airbox and vacuum at the air rail.

If you're on a CSL tune, it's not aware that the PCV is even there, so my bet is if the car runs normally, then terra's hypothesis is right: The harness is probably powered by default such that even if the ECU isn't aware of the valve, turning the car on snaps the valve shut and keeps it that way. Then the system functions as if it were an earlier car (e.g. a CSL) having its oil separator connected only to the airbox. I'd love to test that but my cars are '01 and '02, so I don't own a PCV-capable wiring harness.

[Cubieman]

But to answer your question, I think we're getting pretty close to the definitive answer, no?

Isn't the idle air valve (which is variable and PWM-controlled) going to compensate for the air coming from the PCV? It can compensate within reason, and this would be within reason.

All of the air mass will be calculated by the MAP sensor and IAT sensor, I believe. I think the DME looks at RPM targets to main idle with the correct fueling. This is my grossly oversimplified understanding/mis-understanding of course - feel free to correct.

Very close, and you are above me in the understanding of this system so your insight is quite welcome. I'm just not 100% this valve will not create issues.

Now that the MAF is gone, if the valve lets in air I suppose you could no longer consider that to be unmetered air and the ICV/MAP should be able to figure out whats going on as I think you just alluded to.

[jbfrancis3]

But to answer your question, I think we're getting pretty close to the definitive answer, no?

Isn't the idle air valve (which is variable and PWM-controlled) going to compensate for the air coming from the PCV? It can compensate within reason, and this would be within reason.

All of the air mass will be calculated by the MAP sensor and IAT sensor, I believe. I think the DME looks at RPM targets to main idle with the correct fueling. This is my grossly oversimplified understanding/mis-understanding of course - feel free to correct.

[Cubieman]

Why don't you cap the air rail AND the small bung T'ed off the breather fitting (remove the small corrugated line). That way you can be at ease with everything.

I've got a CSL breather tube on hand, so I will remove the US tube/valve and cap the air rail. This stuff is going through my head all day! Although excited it's finally time to put it together.

[jbfrancis3]

So is there really a definitive answer whether or not this setup with CSL Software will cause a vacuum leak? I've seen this valve left on other CSL airbox conversions.
It turns out ECS won't have a pre-04' rail for a few weeks and I'd like to start working on getting my airbox in tomorrow night.

Dura didn't seem to be having any issues running his setup.
As of now I'm just planning to go get some of those vacuum caps at the local auto parts store and cap off the bung on the rail to the valve. After reading through all the great info in this thread I'm still unsure about this valve.

I guess it comes down to this question: is the valve OPEN or is the valve CLOSED when not energized? I suppose when I've got everything apart I can blow through the valve and find out whats what.

Why don't you cap the air rail AND the small bung T'ed off the breather fitting (remove the small corrugated line). That way you can be at ease with everything.

[heinzboehmer]

And I was also was reminded of the fact that motor oil tastes awesome

Lol. Blowing might have been better than sucking.

[ethan]

And I was also was reminded of the fact that motor oil tastes awesome

👍. Same - really noticing the difference in this Ravenol additive package.

[terra]

The valve is definitely open when not energized. I guess question is does the DME output default to grounded or not. The CSL DME has no control over it, but if the output defaults to grounded, you might be okay.

[Cubieman]

So I took off the breather, plugged the crankcase side hole with my finger then sucked through the airbox side hole, that valve if definitely open.
So I would be led to believe that the bung to this valve on the air supply rail needs to plugged with CSL airbox/software, yet others say it causes no issues.

And I was also was reminded of the fact that motor oil tastes awesome

[Cubieman]

So is there really a definitive answer whether or not this setup with CSL Software will cause a vacuum leak? I've seen this valve left on other CSL airbox conversions.
It turns out ECS won't have a pre-04' rail for a few weeks and I'd like to start working on getting my airbox in tomorrow night.

Dura didn't seem to be having any issues running his setup.
As of now I'm just planning to go get some of those vacuum caps at the local auto parts store and cap off the bung on the rail to the valve. After reading through all the great info in this thread I'm still unsure about this valve.

I guess it comes down to this question: is the valve OPEN or is the valve CLOSED when not energized? I suppose when I've got everything apart I can blow through the valve and find out whats what.

[jbfrancis3]

You were right! Also well done with pulling everything.

I understand better your comments around a fresh air breather and theory of operation. And yes, I agree the check action prevents vapors from escaping with no vacuum draw it seems. I don't envision a scenario where blowby is so excessive that you have net positive pressure in the system, and that check valve would come into play. Rather I'm under the impression vacuum is always going to exceed blow-by forces in an engine with properly sealing rings.

[ethan]

Stock piece from FCP for reference:



My tube:



The check valve has an arrow on it labeled "Top" (meaning to airbox presumably), but the flow through the check valve runs opposite the direction of the arrow haha - thanks BMW.




Makes sense - otherwise crankcase vapors could just bypass the cyclone separator on pre-04 cars with no vacuum draw on the case by way of this tube.

[ethan]

Yes and if we checked which way it, uhhh, checked, then it would tell a lot.

I'm thinking its allows flow up towards the airbox, and checks the other way. I believe you are thinking the opposite (allowing flow from the airbox)?

Interesting! I'll just have to pull mine and check the direction of the check.