Simple queston.(did a search) is there any reason why I should not be able to put a breather over the PCV valve?? studying from the Haynes book and there diagram given(6-19), I can see no reason why this would be bad, given I will cap the other end. Those who have done or thought about this before please responed. FOR ALL WHO ARE GOING TO POST ASKING WHAT BREATHERS ARE FOR DO A SEARCH!

 

I was gonna answer this differently but after looking at the referenced page; I think you probably could. If your states emissions are strict this might pose a problem for you. I put a breather element on the other side of the PCV system to keep air mixed w/ oil from blowing back into my filter/MAF/intake. I wonder, since I have a breater element, air that has passed over the MAF has been metered to help determine the amount of gas to add, but I'm venting some of that metered air out of the breather element. Does that richen my fuel mixture and if so, is it enough to do damage? Maybe I would be better off with a breater element on both ends of the PCV system? Very interesting question to me.

 

Be careful with what you read from Haynes manuals. Of the two thick tubes that are routed to the resonator, the one on the front side is called a Crankcase ventilation tube, while the one on the back is called a Crankcase ventilation hose (see page 4-7 in your Haynes Manual). I don't know about you, but hose and tube are pretty much the same thing to me. And in either case, they are DEAD WRONG about the one on the back. The front one can be replaced with a breather filter. Although there are no performance gains to be had by doing so. Yes an intake with one less opening on it will flow better, but not even a dyno will be able to find results.

Now we get to the one on the back. How do I know that it cannot be replaced with a breather? Because I made my own intake not too long ago, and when the tube is not hooked up to the intake line behind the maf sensor, your car will not be able to hold an idle. Why? Because it is used to measure metered air. So because of this drawback, I had to run basically a POP intake, until I have the time to finish of the intake to include atleast two nipples, one large one for the metered air, and a small one for the little line, for which I have not figured out as to what it is exactly for yet. It is definetly a vaccuum line, but I do not feel comfortable stating what I think it is until I have a better idea.

Off to a tangent now, so if you do not feel like reading more about the routing, please stop now. The following deatils my making of my own intake as opposed to buying one from Ange's group deal not too long ago.

When I was deciding on the intake, and working some calculations out, I had to take some measurements from the engine bay. That's when I noticed that the throttle body opening is only 2.5" in diameter, while the back of the MAF sensor has a 3" opening. So I started taking closer looks at CAI, and CAI upper pipe intakes. And that is when I realised that those intakes use a 3" to 2.5" silicone tube reducer when going from the pipe to the throttle. And having studied some physics, this is a HORRIBLE design. Just imagine the air going from a 3" pipe that is flowing pretty darned smoothly because of the length of the pipe, jumping down to 2.5" within less than half or an inch of tube is just going to kill velocity. But will 2.5" piping flow enough? Hell yah! In order for the engine's output to be limited by 2.5" pipe over 3" is about 350hp. And does 2.5" make more power then 3" piping? Yup! A lot, nope. Percentage wise? Yup. How do I know? I dynoed them. What's the difference, about 3.5 hp and about 5 ft.lbs of torque. My buddy bought a JWT pop charger, and a complete Place Racing CAI. And we dynoed my car bone stock, with the PR CAI upper pipe, and JWT, and with my intake consisting of a 2.5" silicone coupler from the throttle body to a 2.5" aluminized steel pipe, to a 2" long cnc machined lucite adapter to go from the 2.5" pipe to the 3" MAF, to a RACtive double coned air filter (it's an K&N rebadged). I'll break down the runs by intake.

Stock: 163.2hp and 175ft.lbs.
PR CAI upper pipe and JWT: 168.8 hp and about 182 ft. lbs.
My intake: 172.1 hp and 186 ft. lbs.
* All numbers are peak hp, and an average of 3 runs, all done within 1 hour, with temperatures around 20 degrees celcius with about 85% humidity.

Yes about 3hp and 4 ft. lbs isn't much, and can't be detected by the buttometer, but it is a noticeable percentage gain over the PR CAI. The PR made 5.6 hp and 7 ft. lbs over stock, but my intake made 8.9 hp and 11 ft. lbs over stock.

As for a description of what the charts looked like, off the line, stock, PR and mine all were pretty much the same, with the PR and mine starting to noticeably pull away from stock around very low 2000 rpm. And from there, the two slowly separated. The PR and mine basically looked like identical curves, with my intake just slightly stretching out the chart.

The intake is working out so well, I'm already setting up to sell them locally to people I meet at races, and to friends in the area. I just need to finish off my finals, and I'm going to produce about 3-5 to sell right away. If people like them, and word gets around, I'll make some more.

 

Actually, no one, anywhere in North America will get passed a visual inspection if they use breather filters instead of the hoses.

And as for your concerns of oil getting ont the maf and filter, forget them. First of all, there isn't that much pressure relative the vaccuum and volume of the intake, secondly, there is no possible way for the gasses to travel the other direction in the intake to foil either the MAF or filter. It is simply impossible. Also, that is NOT the PCV. The PCV is actually located close to the throttle body. This is just crankcase ventilation. And as for your concerns about losing metered air, don't. The gas that comes out of the crankcase ventilation hose is not from ingested air, unless you have some SEVERE leaks in your engine. Yes there is SOME combustion gas in there, but it is lost from the combustion system already.

And like I said in my other post, the other is NOT crank case ventilation, but rather metered air for idle.

 

on 2nd thought I think it is more reliable to put a breater on the valve then on the crankcase(my curent set up)because it dose not alow any air back into the system like on the crank case. Dose alowing the presure in the crank case to ventilate at all times by puting a breater on hurt anything???But the air we are letting escape is no longer fresh air its exhaust to so it should not hurt any MAF readings.

 

That's the point of a breather FILTER. And I have a feeling that disconnecting the PCV will set off check engine lights, because it should be built into the emissions system for it to go off.

Basically, if you want to put a breather filter on the front bank, it will NOT do any harm to the car whatsoever, just as long as you install it so that all air must be filtered (don't want dust getting in there). And as for the PCV, I am pretty darned sure you will get a check engine light if you do what I think you described that you will try.

 

So can you put a breather on the PCV valve???? reason being to help keep things clean.

 

You type faster then me

 

Before I say yes, I want to know EXACTLY, FOR SURE, that we are talking about the same thing. The PCV valve is a small little valve about 1/2-2/3" in diameter. It is found right behind and below the throttle body. Page 1-23 of the Haynes Manual.

 

Why would the CEL go off?? I thought the only difference betwen the crank to resonator and pcv valve to wear ever was the valve

 

Yes ,we are talking about the same thing.

 

I appreciate your input and your intake sounds very interesting but I must disagree with you on one point. It is very possible for intake gases to travel the other direction. This is why you will sometimes find oil on your air filter. I'm not talking about K&N oil, I'm talking about black, sooty, engine oil that was found on my stock intake filter. Maybe the PCV valve was sticking or something but non-the-less oil can blow back. Maybe it happens when you let off from WOT? When I said the other side of the PCV system I simply meant the other side of the loop. I know where the PCV is, and my breather is on the vent side. Not flaming just covering my a$$. Too see a car that has no PCV system in use, check out PapaSmurfs set up. His car is a freak of nature - he has breather elements everywhere. http://www.cardomain.com/member_page...=143237&page=2

 

It all depends on the sophistication of the ECU. I know for a fact that if I were to do so on my Volvo 850 Turbo, it would. On the Maxima, I assume it would. It very well might. However, it may not.

It's just my warning to you that it may set off the CEL.

 

Well, I guess I should've included under normal operating conditions. I have never ever had engine oil or any crankcase gasses going the other direction (towards the maf) on any of 4 cars I have maintained.

The thing is, you have the intake manifold which has an opening to create vaccuum that is attached to a tube. This tube has a PCV valve at the end of it, and that is attached to the crankcase. Are you saying you want to put a breather on both the intake as well as the crank case?

 

Slap the breather on top of the PCV valve and cap the hose going out of the top of the PCV valve.Thats what I want to know if I can do.Wait when the PCV blowes its going up towerds the hood right.What dirtion is the air flow?

 

Gasses will flow from the top of the crank to the PCV valve, through the tube, then into the intake manifold. You do know that the PCV valve is IN the tube correct?

 

yes I know.

 

AHHHHHH, the way you just explained it makes so much more sense for me. I thought that air went in through the PCV side and exited through the front cylinder bank through my breather element. But from what you've just said; it is now clear to me that when I accelerate, the engine creates a vacuum at the PCV valve side that then pulls air in from the breather element. Is this correct? IF this is the case then my earlier question about losing "unmetered" air is opposite of what is really happening. I would actually be adding unmetered air wouldn't I? The Haynes illustration isn't the best for the PCV system. Ultimately can you answer this for me, I'm so confused, which way does the air flow through the PCV system? PCV to breather or breather to PCV? thanks.

 

I thought I new how this system worked but now I am completely confused.Stupid Haynes diagram

 

We need to stop talking about breathers first, and just worry about flow direction. From there, where to put breathers will be logical.

There is a crankcase with an unsealed opening at the top. A tube with a PCV valve inside of the tube, right at the bottom of the tube, where it plugs onto a nipple on the crank case. With the engine running, a vaccuum is created on the side of the tube that does not have the PCV valve in it, because the open end of the tube is plugged onto a nipple on the intake manifold.

IF you want to replace the PCV valve and the tube between the crank case and the intake manifold, you will have to put a breather onto the intake, as well as a breather on the top of the crank case. YES, if you did this, you would be adding unmetered air into the engine. And I can't possibly see why you would want to.

 

IF you want to replace the PCV valve and the tube between the crank case and the intake manifold, you will have to put a breather onto the intake, as well as a breather on the top of the crank case.

Why put a breather on the intake side? I want to leave the valve attach a new hose >adapter> Breather. cap the OLD hose leading back to the intake. am I makeing sense?

 

So you want to put a breather on the top of the crankcase and just cap off the intake? Why keep the hose at all? Just cap where the metal is.

So now, it'll be, crank case to breather filter, lack of tube, and capped off intake?

 

All right, thanks for all the replies. I've put down the Haynes manual and am now looking at my FSM - much better write up. I am happy with my set up but will let you all know what the FSM states. "During partial throttle operation of the engine, the intake manifold sucks the blow-by gas through the PCV valve. Normally, the capacity of the valve is sufficient to handle any blow-by and a small amount of ventilating air. The ventilating air is then drawn from the air cleaner, through the hose connecting air cleaner to rocker cover, into the crankcase.
Under full throttle condition, the manifold vacuum is insufficient to draw the blow-by flow through the valve, and its flow goes through the hose connection in the reverse direction. On vehicles with excessively high blow-by some of the flow will go through the hose connection to the air cleaner under all conditions." Damn my hands are sore from typing. Don't know if this cleared anything up but its very interesting to me for some reason. Maybe it's because I'm neglecting my homework right now. From this I would think that you could cap everything on the intake side and vent everything off the engine side? I'm keeping my set up but would like to know if you do this. I'm done for a while.

 

So under light load, crankcase gasses are pulled through the PCV valve because of the intake vaccuum, which may cause some slight amounts of air being pulled into the valve cover at the front of the engine, which if stock, is attached to the intake tube. But under heavy load, the valve's opening is insufficient, therefore causing air to be drawn from the opening in the valve cover, and intake air drawn from the intake manifold to the tube, to the PCV valve, to the top of the crank case right?

Makes sense. So if you aren't too concerned about polluting a bit more by venting crankcase gasses, there should be no reason why you can't seal up all the openings in the intake that are PCV related, and putting breather filters on all the PCV openings.

 

That was my assumption from the begining!!! I wanted to know if anybody had done this before. I did it.

 

can anyone pleased tell me where i can buy a cap to cap up the intake part