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Old 09-11-2019, 06:16 PM
Join Date: Jun 2014
Location: Omaha, NE
Posts: 1,235
cn90 is on a distinguished road
- The modification I posted previously works just fine for a cost of $30 for parts.

- To plug existing system hoses: as long as you have some rubber material to plug any factory open hoses, it is OK. The idea is to de-commission the factory PCV system.
1998 E39 528i 5sp MT
2006 E53 X5 3.0 6sp MT
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Old 09-12-2019, 02:40 PM
Join Date: Jul 2011
Location: Ro
Posts: 4
Xelo is on a distinguished road
CN90, could you please be more specific as to how you've plugged this original open ends of the CCV hoses (marked with big red arrows)?

As we know, open end as female - meaning you had to insert something into them, but how did you make sure it is tight/snug ?

Thanks !

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Old 09-18-2019, 07:18 AM
Join Date: Jul 2011
Location: Ro
Posts: 4
Xelo is on a distinguished road
Hello again,

I am planning to do this modification also (including a catch can) but after days of studying I've stumbled upon one issue that has not been adressed (or addressed too little).

There are 2 versions for any PCV system: open and closed.
Open ones are venting the blowby gases to atmosphere, closed ones (as in this case for the M54s) are venting the "filtered" air back into the engine through the intake manifold.

Now comes problem #1: this "filtered" air is not measured .

MAF measures air coming through the intake manifold, but the one coming back from the valve cover through this modification is routed back into the IM AFTER the MAF (through distribution cover) - so there is a surplus of air going to the cylinders, although the ECU has measured less and O2 sensors will measure more.

This will cause crazy fuel trims.

Any schematic of closed PCV system on the net is described as having a venting hose coming from the air filter (so metered air) which allows the crankcase to breath.

See examples below:

Returning to the case of M54 engines: OE system does not have a supplementary/aditional valve cover breather as I remember. The only port of the VC is the one going to the CCV.

So this raises so many questions:
1) Why does the OE M54 CCV system does not have a breather allowing the crankcase to draw air from the intake
2) Would this breather be a good idea as it still allows vacuum but also protect engine seals ?
3) Where would the best connection for a breather be ? I have heard a case where the guy connected a hose from the vacuum F connector in the intake boot to the oil dipstick. If so, would this need a non-return valve (for the improbable case oil from the crankcase/oil pan would come up and flood the intake) ?

My take on this:

Last edited by Xelo; 09-18-2019 at 07:24 AM.
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Old 09-18-2019, 11:38 AM
Join Date: Mar 2016
Location: Saskatchewan Canada
Posts: 882
80stech is on a distinguished road
Good for you for trying to think things through and you are justified having some concerns, but you have some errors in your information. One big problem is that you don't have a diagram of the factory CCCV system. A CCCV system is NOT a closed PCV system. Also, I think it would be good if you started a new thread on this.
1988 325is (purchased new)
2004 X5 3.0 (new to me) 2005 X3 2.5 (new to wife)

Last edited by 80stech; 09-18-2019 at 11:43 AM. Reason: add
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Old 09-19-2019, 06:21 AM
Join Date: Jul 2011
Location: Ro
Posts: 4
Xelo is on a distinguished road
Umm, sorry, but could you please me more specific about the errors ?
My drawing explicits exactly what you guys are talking about for some time: transforming the CCV into a PCV.
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Old 09-24-2019, 01:13 PM
Join Date: Feb 2016
Location: Florida
Posts: 222
trentcdrums is on a distinguished road
OP - is that a clutch fan or electric fan?
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Old 09-25-2019, 11:05 AM
Join Date: Feb 2016
Location: Florida
Posts: 222
trentcdrums is on a distinguished road
Originally Posted by $chlitz View Post
Where the heck are you guys finding the little plastic plugs like the one used to plug the black plastic air distribution runner? I went to Autozone, Advance and Harbor Freight and found nothing. Plenty of vacuum caps, which would work for the dipstick tube, but that isn't going to work to plug the hole. Frankly, I'm tired of running all over town...
i finally found something similar ---
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ccv, oil separator, pcv, vacuum, ventilation

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