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Discussion Starter #1
Hi, there probably already is a thread about crankcase breathers, however they are in different sections and 3.2 Busso definitely has at least different ECU and the stock ventilation system is also different then for example on GTV.
Does anyone have experience with fitting them? As my stock flex elbow was failing and I do not like to drive with one wrapped in duct tape, I just ordered and fitted regular 3' bendable hose for connecting airbox to TB and put a mini filter on the crankcase end connected to old elbow. Looks good, sound is nice also, however when car is cold both idle and throttle response became really rough. Once warm at least little (over 50° C) it is stable as before. Subjective performance about same, with fuel consumption I have to wait a while to get data, however looks either same or better. Any hints what may cause the cold behavior? Is the PCV purely mechanical or is there some ECU control as well?

Other thing is the oil smell which is much worse then I expected.

Currently I am considering fitting a one-way valve between filter and valve cover and some small vacuum pump with hose exiting behind everything which can go to cabin on the second breather (currently going to plenum). Anyone tried this setup before? Is there any convenient way to tap DC directly from alternator?

Any advice appreciated.
 

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Does your GTV have one or two breathers? I'm assuming 2, try remove the other one also and block the PCV valve on the intake manifold off. I was getting similar problems when I removed only one. When I removed both and blocked the PCV off, it was all good.
 

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Discussion Starter #3
Does your GTV have one or two breathers? I'm assuming 2, try remove the other one also and block the PCV valve on the intake manifold off. I was getting similar problems when I removed only one. When I removed both and blocked the PCV off, it was all good.
I do not have a GTV, I have 3.2 GT, that is why I posted it in GTA section... But this would make sense, still does not explain why it does it only cold but disconnecting the 2nd is probably what I will end up doing. Thanks for reply anyway.
 

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I did same on my 147 GTA, took both breathers and closed both intakes, one on the metal manifold with a blank screw, one on the silicone bend with a plug
 

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Does your GTV have one or two breathers? I'm assuming 2, try remove the other one also and block the PCV valve on the intake manifold off. I was getting similar problems when I removed only one. When I removed both and blocked the PCV off, it was all good.
If you remove one, then you are hoovering unmetered air into the engine via the breathers. This has a habit of messing up the idle. Either remove both, but be aware that the oil smell is likely be bad, and a picky MOT guy could fail you. Or buy the proper elbow from partsworld for £99.
 

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Got a few questions.

Why not port the vent tubes to an oil collector?

What are the two tubes at the back of the plenum for/from?

Is a certain amount of oil vapour expected in the programming of engine ecu. It's not monitored so what happens when this removed?

A presume you get a cleaner burn without the oil vapour but are there any disadvantages?
 

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Pretty sure this is how the system works on the CF3 - its not a breather for each bank but the front bank is the entry point for clean air, and the rear bank is where the oily vapour air is vacuumed out.
 

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I did same on my 147 GTA, took both breathers and closed both intakes, one on the metal manifold with a blank screw, one on the silicone bend with a plug
Presumably you have a catch can? Is it connected to your air intake system to give it some draw or just open to atmosphere on the other side of the catch can?
 

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Pretty sure this is how the system works on the CF3 - its not a breather for each bank but the front bank is the entry point for clean air, and the rear bank is where the oily vapour air is vacuumed out.
I’ve just been playing with this as a result of trying to fix my poorly GTV engine.

The whole engine runs at a negative pressure internally. If you leave one breather on, and then block the other with something, it will pull a considerable vacuum - which is caused by induction. As long as the engine is not knackered with a massive blow by, the induction volume is far greater than anything generated within the engine.

So both the breathers are drawing air out of the engine - actually, once it is at steady state, then they are simply maintaining vacuum, rather than actively pulling air out.
 

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Discussion Starter #10
If you remove one, then you are hoovering unmetered air into the engine via the breathers. This has a habit of messing up the idle. Either remove both, but be aware that the oil smell is likely be bad, and a picky MOT guy could fail you. Or buy the proper elbow from partsworld for £99.
My initial understanding was that the PCV valve sitting between the plenum and the second breather should be somehow controlled to shut off at idle and WOT and allowed to open only if some throttle/load condition are met but it seems that it is not the case and it is simply sucking air whenever there is vacuum in the manifold.

Got a few questions.

Why not port the vent tubes to an oil collector?

What are the two tubes at the back of the plenum for/from?

Is a certain amount of oil vapour expected in the programming of engine ecu. It's not monitored so what happens when this removed?

A presume you get a cleaner burn without the oil vapour but are there any disadvantages?
Current plan is to take he second ("output") breather and run some small hose under the car.

I dont know which two you tubes mean but there are definitely at least fuel vapor ventilation and brake booster lines going from back of the plenum.

As for ECU considering oil vapor, I would highly doubt that.

Disadvantages can be poor idle if you do it half-way and oil smell if you do not route it sufficiently away, other than that possibly MOT consideration.
 

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Presumably you have a catch can? Is it connected to your air intake system to give it some draw or just open to atmosphere on the other side of the catch can?
catchcan, and pipercross metalfilter to outside air ....

Also tried mini catchcan in each breather at some point:
 

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Discussion Starter #13
I did same on my 147 GTA, took both breathers and closed both intakes, one on the metal manifold with a blank screw, one on the silicone bend with a plug
What kind of screw did you use to blank the manifold please?
 

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I just went to a big hardware store, and got a copper blanking screw, as used for water pipes etc. ;)
 
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