EGR breather, Valve cover

[Meegs]

I got a question that kinda buggs me. On the oil fill there is a stub that from the factory had a tube going to the EGR. My question is what purpose does that have? I have seen many 5.0's with simple vavle breathers over the stub and a cap over the EGR port. That being said what purpose does the EGR have, or function? I have looked into getting a larger EGR spacer and for 20 bucks I don't think it comes with all the bolt ons so I would have to salvage those from my current EGR? But if I am thinking right why should I even have a EGR if most people cap off the end? Also my car has a supercharger if that matters.?

[CleanLX]

Many people remove their EGR after "turning it off" through the processor.
Or, you can keep the spacer on and install a block off plate.
But until you tell the computer otherwise, you need to run the EGR.
I have a EGR, its the same size as my throttle body(70mm). And yes, its as simple as removeing the old shtuff off the stocker and bolting to the larger diameter EGR.
So there are several options.

[Sweet35th]

On the oil fill there is a stub that from the factory had a tube going to the EGR

On the oil filler neck that tube should NOT go to the EGR valve, that is a breather tube. By placing a breather on that nipple off the oil filler neck you create an unmetered air leak on mass air flow equiped cars. This can actualy cause a lean condition, and should not be done.

The EGR is used to direct inert gasses (exhaust gasses) into the cylinders. This gas displaces the air/fuel mixture in the cylinder there by reducing cylinder volume. Because of the reduced cylinder volume less air/fuel is taken into the cylinder. This there by produces less heat which lowers NOX emissions. The bennifits of EGR then come into play. Because less heat is created, more ignition timing can be run when EGR is applied, creating more power with less fuel. And because of that, combined with less fuel being taken into the cylinder, EGR increases fuel economy.

EGR is very benificial, and removing it without having the PCM programed for it being removed can cause severe detonation problems, low power, and poor fuel economy.

If a vehicle has aftermarket cam/cams, the increased duration and over lap "generaly" lowers cylinder pressure, and there by creating less heat making the need to reduce NOX gasses redundant, and at that time EGR can safely be removed, however the PCM should still be programed to account for it.

[5.0Cobra]

That breather tube goes between the oil filler neck and the throttle body. On a NA car, you want to leave it there to prevent unmetered air. However, you said you have a supercharger? That tube should NOT be hooked up in the factory manner with a supercharger. Under boost, you will be pressurizing the crankcase. Most supercharger kits have you route a new tube from the filler neck to the airbox instead. This still allows the PCV system to operate properly and prevents crankcase pressurization (assuming your PCV valve is good enough to seal under boost). Some people just run a breather cap, which is doing the same thing.
This will introduce unmetered air, but only under vacuum and a small amount. Most people don't have any problems running like that, but some claim to have idle issues.
If you really want to eliminate unmetered air and crankcase pressurization, you can run a tube from the intake side of the supercharger (after the MAF) to the oil filler neck, with an oil separater and check valve inline.
The unmetered air topic has been beaten to death on corral. I honestly don't see how it can be a problem in supercharged applications unless you are pulling a huge amount of vacuum at idle.

[Sweet35th]

The unmetered air topic has been beaten to death on corral. I honestly don't see how it can be a problem in supercharged applications unless you are pulling a huge amount of vacuum at idle.

Most cars with mild cams are still pulling close to 18in of vacuum at idle, and around 8-10 at cruise. Thats decent vacuum.

The issue isnt with manifold vacuum however. Its with crankcase vacuum created by the PCV system. (The PCV does supply intake vacuum to the crank case, however the vacuum at the breather itself will not reach intake vacuum.) This crankcase vacuum draws air in from open orifices such as an open breather.

Now the old EEC IV processor in the 5.0ls fuel statigy is a lil bit on the retarded side (slow) so there is not a large issue with it, however on long trips fuel trims will certainly move up past the normaly acceptable range.

However on EEC V vehicles, with much more stringent emissions complaince and far more advanced fuel stratigy, I assure you that the second you open the breather orivice to unmetered air, the STFTs will begin rising. And if the breather has low enough restriction, it will easily reach the point of setting a P0171 and P0174 after it pushes the LTFTs far enough (usualy 25% but some vehicles will set at lower).

Corral can kiss my ass. That web site is filled with some many knuckle heads that spend too much time reading the wrong way about how stuff works, from some other knucklehead that the he knew what he was talking about. Then spout out information that is not entirely true, with a very poor understanding of how things work. And certainly without and real experiance to back up anything they have to say.

[5.0Cobra]

How do EEC V cars solve the problem of unmetered air in supercharged applications? How is the PCV system setup on new Cobras and Lightnings?
There are obviously a lot of factors that could affect whether unmetered air could be a problem, but it seems like most boosted EEC-IV cars do just fine with a breather. I have not seen any proof of exactly how much unmetered air gets in, but it would be an interesting experiment.
I agree a breather is not the ideal setup, but it does prevent the crankcase from being pressurized by boost both directly and from blow-by under boost.
Also people seem to worry about the unmetered causing a lean condition and blowing up their engine. What never gets mentioned is that this lean condition can only happen at idle or cruise, when running slightly leaner is probably not going to kill your engine. Under boost, the PCV is sealed, there is no unmetered air, so it will not be lean. I'm guessing there could actually be a rich condition, depending on the fuel trims.

Again, the best way to solve all the problems seems like running the tube from the oil filler to supercharger intake, after the MAF, and putting an oil separater to keep oil from getting into the supercharger. However, very few people seem to ever do this. Do you know of any supercharger kits that come with this or don't create unmetered air?

[Meegs]

WOW, great feedback!! Thanks alot! I am in the process of putting together a blow-off valve in. I think I will run a tube from the filler neck to the tubing inbetween the valve and the power pipe. I would not want to run it inbetween the vavle and the intake/TB would I? That part would be under boost. I looked up a separater in Granger and from Ingersol Rand it is going to cost me $140 Wich is not the end of the world but I hope it takes care of the lean codition that I am not sure I have or not>.

My only concern is that I will be puting HOT air back into my intake. I guess that is the price I am going to have to pay right?

I can't thank you guys enough!

I design civil projects by trade but when it comes to automotive issues I get kinda lost. I took my car to JHM when I first started messing with it and walked out of there with a $1,400 fuel pump?! Nope not even a dyno tune or chip. Since then I got pissed off with speed shops and have started to do mechanical work on my own. I purchased a blow-off valve from Powerdyne and spent $185 on a part that I just looked at Granger and saw that it cost $35 I guess that it also came with radiator hose to tap into the valve so that must be where the extra money went?!

Keep up the good info for us newbies!!! We really do appreciate it!
~Justin

[5.0Cobra]

Justin, that sounds like a good plan. I think you should be able to hook up an oil separator much cheaper by just using an air compressor air/water filter, like campbell hausfeld, etc. Steeda sells one with a bracket. You could also look up user "Sinful" on corral. He's selling kits for about $60 that include a PCV valve and 2 separators- 1 from oil filler to powerpipe, and 1 from PCV to intake (to prevent oil from getting sucked into the intake).

Don't worry about hot air going into your intake. It is a small quantity (in my opinion) and coming from the crankcase.

You are just running a breather right now? I wouldn't count on this taking care of a lean condition. You might want to consider tuning with a chip, tweecer, etc.

[Sweet35th]

How do EEC V cars solve the problem of unmetered air in supercharged applications? How is the PCV system setup on new Cobras and Lightnings?

On EECV vehicles you can compensate with MAF transfer function to correct for the unmetered air entering the engine at idle and cruise from having an open air style breather system.

The cobras and lightnings are a lil differance situation. Because they are roots type blowers residing on the believe the actualy intake, during normal operation they have vacuum before the blower (because the blower is after the throttle body). So the PCV system operates similar to that of an NA vehicle. The breather is routed to before the throttle body, so it works normal as well. They do though because of possitive crankcase pressure created under boost have oil ingestion problems. Be it assisted by the venturi affect across the PCV port in the intake, or by the crank case pressure pushing the oil past. This is why some owners run a oil separator.

Some Lighting owners have tried to run a open breather to corret the situation, believing that much of the oil is from the breather system. It typicaly does little to help, and does create an unmetered air leak, and many people eventualy get a P0171 and P0174. Alot of tunners (JLP, JDM, ECT) will tune to correct this.

I have not seen any proof of exactly how much unmetered air gets in, but it would be an interesting experiment.

No experiment needed, its fairly simple explanation actualy. The PCV system is constanly supplying manifold vacuum to the crankcase. This vacuum then through the crankcase reaches the breather, where in an open breather system, it draws in air that has not been measured by the MAF. The extent of the lean condition is reletive to how free the air flows through the eliment of the breather. But the condition does not only exhist at cruise and idle, it exhist any time there is vacuum to the PCV.

Usualy at least once every few months I get a vehicle in with a check engine light that has recently had its oil changed at MonkeyLube or what not. Pull codes and low and behold its a P0171, p0174. What do I find? The oil filler cap missing. The same condition occured that occures when running an open breather.

[5.0Cobra]

The extent of the lean condition is reletive to how free the air flows through the eliment of the breather. But the condition does not only exhist at cruise and idle, it exhist any time there is vacuum to the PCV.

It would still be interesting to see actual numbers to show how much unmetered vs. metered air is being sucked in. I believe you that it's enough to throw codes in EEC-V vehicles.
A breather cap is pretty much wide open so it doesn't add any more restriction, compared to the small tube supplied by paxton/vortech which probably is more restrictive. That could be one reason why they supply the tube rather than just a breather.
I think that could also be bad if it is too restrictive to vent the crankcase under boost, leading to leaks, etc. I liked the idea somebody on corral had to run the tube from oil filler to powerpipe (w/ separator), plus add a breather with a check valve in case excess pressure did develop. Kind of a safeguard really. No unmetered air, just "over-metered" air if the check valve opened.

[Rick]

My Paxton kit ('98 Cobra) ties in the breather tube between the MAF and supercharger inlet. That results in the PCV air flow being measured by the MAF. I've had no boost related oil migration issues so far. I guess my PCV valve is sealing well under boost and I haven't cooked the temper out of my piston rings yet.