pardon my ignorance

3zubVdub

Well-known member
Joined
Dec 30, 2000
Location
Washington DC
TDI
2010 JSW silver 6sp MT; 2011 Golf 4DR DSG Shark Blue; Retired - Jetta gls 2001 baltic green traded for (also retired) 2005 Passat GLS
Help please,

What is the difference between the EGR and the CCV?

The main reason I ask is beacuse I have just finished reading the debate on EGR disconnect at the emissions section and as I was picking up mt new car yesterday I was approached by another TDI owner who was adamant that I should disconnect my EGR?? His reasoning seemed to be that I would not have a crud problem in my intake in the future.

This post is not intended to spur flames from anyone. I just am not clear about disconnect of EGR? vs CCV?

After all the VW engineers put these components there for a reason
, right?
 
M

mickey

Guest
YOU STUPID SON OF A....oh, wait. You said "no flames." Sorry.


"CCV" is the crankcase ventilation system. (Known as "PCV" on a gasoline engine, but it'll answer to either name.) It vents blowby gases from the crankcase. Look at the top of your engine. That round, black disc thingey with the little black hose coming out of it is the CCV fitting. Unlike a PCV Valve it isn't really a one-way "valve", though. Just a glorified plastic elbow fitting. Crankcase gases are routed into the air intake system upstream from the turbo, and eventually they are burned in the cylinders. PCV/CCV was probably the earliest "pollution control" system installed in cars, and was done to help prevent unburned hydrocarbons from escaping into the atmosphere and causing smog. It has absolutely NO ill effects on a car UNLESS you have an intercooler, like we do. The fuel and oil fumes in the CCV gases condense on the cool interior surfaces of your intake system, coating them with a thin layer of oil. That wouldn't be a problem, but that oil partially insulates the intercooler and reduces its efficiency. Airflow isn't restricted in any meaningful way, so it doesn't affect cruising fuel economy. But it does cut down your maximum power output under heavy boost a little bit. Routing the gases to the atmosphere is the simplest (and most illegal) way to prevent intercooler fouling. Some folks install some kind of filter on the end of their "elephant hose" in an effort to condense and capture the rouge oil and fuel. The most elaborate systems filter out the fumes and then return the gases to the stock fitting in the intake system, and the condensed liquids are captured in a sump of some kind. Drivebiwire has even rigged up a drain to automatically return the nicely distilled motor oil to his oil pan!

EGR means "Exhaust Gas Recirculation", and does exactly what the name implies. A portion of the exhaust is sucked back into the engine to be "re-burned." NOx (Nitrogen oxide) emissions are reduced because the effect of EGR is to reduce your engine's efficiency! Because some of the oxygen in the intake charge is replaced by nasty exhaust the fuel doesn't burn as efficiently as it should, and thus the engine produces less NOx. It does, however, make more soot, so you're really just trading one poison for another. The gub'mint has decided that soot is better than NOx, though, so we're kind of stuck with it.

The EGR valve is open whenever the intake air pressure is less than the exhaust backpressure at the EGR outlet, which means that it's open pretty much always except when there is a lot of turbo boost. EGR isn't particularly good for ANY engine, but it's especially evil on a diesel because the exhaust contains a high concentration of soot. (Relatively.) The soot combines with moisture inside the EGR valve housing and your intake manifold and will gradually plug them up. How quickly that happens depends on your driving habits, atmospheric conditions (especially humidity) and fuel quality. But sooner or later your intake will be clogged to the point that it will seriously affect engine operation. The solution will be to have the intake manifold pulled and cleaned out. You can easily keep an eye on the situation by pulling off the last rubber intake fitting just before the EGR valve housing and looking in the housing. Once the thing gets more than about 10% to 20% clogged it's time to fix it. (Unless you're Ric, who believes that the intake system is "50% overdesigned" and that the fact his TDI is sipping air through the equivalent of a swizzle stick isn't a problem.
) Anywhere from 50,000 miles to 150,000 miles will be the interval, depending on the factors described above.

If you could, in theory, ILLEGALLY disconnect your EGR valve your NOx emissions would increase by a factor of TEN! Your soot output, though, would decrease. Your fuel economy would improve slightly. Your intake would stay clean. Your oil wouldn't soot up as quickly because the blowby gases getting past the rings would be cleaner. All that internal cleanliness would mean that your engine would last a bit longer. And, if you get caught, you'd go directly to JAIL.

-mickey
 

3zubVdub

Well-known member
Joined
Dec 30, 2000
Location
Washington DC
TDI
2010 JSW silver 6sp MT; 2011 Golf 4DR DSG Shark Blue; Retired - Jetta gls 2001 baltic green traded for (also retired) 2005 Passat GLS
Thanks for the quick reply, mickey.

How's the evil beetle coming?


So, if I follow you correctly the EGR does as it says
and recirculates exhaust gasses. Does this work the same as on a gasser? i.e. free radicals (?) in the exhaust gas help burn the new charge of fuel during complression? Or in our case after injection?

Thanks again, I'm looking forward to some miles and soaking up all the info I can from the forum.

Cheers!

[ April 05, 2001: Message edited by: 3zubVdub ]
 

Davin

Top Post Dawg
Joined
Jan 4, 2001
Location
L.A.
TDI
2001 Golf GLS 5spd blk/blk
AFAIK the purpose of the EGR on our engines is to reduce combustion temps in the cylinders. NOx production is directly related to combustion temp, so lower temps mean lower NOx!

In terms of disconnecting the EGR, if not done "creatively", the service mechanic will most certainly know. Everyone else will know that something is wrong, be it the EGR or anything else, because your check engine light will come on.

There are no performance benefits of disabling EGR... the only benefit is in keeping sludge from building in the intake. Of course, there are less legally questionable and environmentally-friendly ways of doing that, namely installing an oil separator/filter on your CCV line. The sludge that so many people see in their intake is a combination of soot from the EGR and oil vapor from the CCV. Eliminate one or both and the problem is solved.

-davin
 
M

mickey

Guest
Disabling the EGR is as simple as yanking the vacuum hose off it. But the ECU will notice and store a "code." To prevent that, you need to fool the ECU into seeing the expected from in air flow through the MAF when it sends the "Open EGR" signal. And that's all I have to say about THAT. Fiddling with your emission controls is ILLEGAL, and not a subject to be openly discussed in the forum.

On a totally unrelated note, you can join the Epsilonian Freedom Fighters if you want to help us with our plans for conquest of this third-rate little blue marble. Contact Commander Valois for details. No NOT mention "EGR" in your e-mail or it will be deleted!

-mickey
 

weedeater

Top Post Dawg
Joined
Mar 17, 2001
Location
Reston, VA
TDI
Jetta, 2001, Baltic Green
Funny you should mention these two things.

Diesels have a CCV rather than a PCV fitting because diesels don't draw a vacuum. No throttle plate, no intake restriction. Usually the CCV is essentially a straight pipe, though some have a diaphram that makes it a one-way valve of sorts.

PCV/CCV cuts down hydrocarbon (HC) emissions. As explained, it directly impacts the operating efficiency of the intercooler by coating the inside with oil mist. Also, the intercooler is the low spot in the plumbing. Cleaning it out as part of maintenance can take care of the problem.

EGR sends a portion of the exhaust back into the intake, usually no more than 20% of volume. Since there is no oxygen remaining in the exhaust, it lessens NOx production during combustion and lowers the combustion temperature.

I was reading up on this last night. For gas engines, the EGR valve opens during acceleration and cruise, closing during deceleration and idle. Diesels are the opposite. With newer engines (gas) the loss of power/torque is minimal to none compared with the NOx reduction.

I saw something on Motorweek (Goss's Garage) about a new system out there for cleaning EGR passages in engines. Seems that the stopped up plumbing is not limited just diesels. Plugged up passages cause knocking, which I'm not sure you would ever see in a diesel. After all, what is a diesel engine but a big set of knockers! (Pistons, that is.)
 

jayb79

Top Post Dawg
Joined
May 20, 2000
Location
Exeter,NH
The valve in the CCV is to keep the motor from running away(accelerates uncontrolably) on crankcase oil.
 

justme

Veteran Member
Joined
Jun 14, 2000
Location
Hanover, NH
For what it's worth (practically nothing), I just pulled the intake on my new (used) NB with 65k miles and found it to be clean as a whistle, with a stock setup. I certainly intend to keep the CCV and EGR on this car at least.
It's easy to monitor the state of the intake crud periodically, so you can always decide to pull that stuff if a problem develops for that car. By keeping it stock you are reducing pollution, and the car might be OK with it anyway.
 

SoTxBill

Top Post Dawg
Joined
Dec 14, 2000
Location
its not the base, its the additives!!
TDI
13 passatdsg 10 jetdsg, 09 jetdsg, 2006 jetdsg, 2001Jet, 96passat, 86jet, 81 jet, 78pickup all vw diesel.
I really believe that cold weather and high humidity has more to do with the build up.. assuming all other factors are constant... I was hoping that we could gather info at the gtg's with info of the climates of the drivers to see if that is a contribitor..

I also suspect driving styles can contribute..

such has hard deacelleration and down shifting causing prolonged ccv "sucking" and or short trips where the engine never warms up fully...

hopefully we can gather info on the forum to see if there are other factors that aggrivate the situation... thanks bill
 

Hanover

New member
Joined
May 13, 2001
Location
Ga, USA
davin.....

This "oil separator/filter" you speak of, is it installed inline? Does it require unhooking the EGR system?

I would like to leave the ERG connected, but keep oil out of the inercooler.

Can you please go into more detail about this mod, such as where to get the parts?

Cheers,

Hanover
 

Davin

Top Post Dawg
Joined
Jan 4, 2001
Location
L.A.
TDI
2001 Golf GLS 5spd blk/blk
Hanover,

Yes, to keep the CCV system closed, a filter/separator is installed inline between the breather cap on the valve cover and the hose inlet to the intake.

I haven't performed this mod, so I can't help you with parts, but I know that several other members have done it. Do a search for "Racor" and you should find some messages about installing a Racor commercial CCV filter (also see www.racor.com). Also, GeWilli has fabricated a cheap homemade filter out of PVC and aluminum wool. See http://forums.tdiclub.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=17&t=000794

-davin
 

Joe Romas

Veteran Member
Joined
Aug 13, 2000
Location
Columbus, Ohio USA
TDI
2014 Jetta Sprotswagen
Mickey, hold on a second! I had a bad
. Just a glorified plastic elbow fitting on a 96 passat tdi and it caused it to use 1 quart of oil every thousand miles and of course the intercooler had oil in it too. After the dealer replaced the valve it didn't use any oil between changes even when it passed the 100k mile mark.

Joe
 
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