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  #11  
Old 06-29-2009, 10:21 AM
olds olds is offline
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Originally Posted by wedged View Post
ah, bliss.... you just have to love it.
Is that directed toward me?? look guy, I'm not the one who thought an EGR valve is directly related to exhaust temperatures. It's a friggin valve.

And yes, if there is no PCV valve on an engine that should have one, it will have all kinds of hard running symptoms. But don't take my word for it cuz I'm young
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  #12  
Old 06-29-2009, 04:14 PM
wedged wedged is offline
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Check into it and you'll see that it's not what "I think" EGR is for, but what it actually is for.
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Old 06-29-2009, 09:12 PM
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Check into it and you'll see that it's not what "I think" EGR is for, but what it actually is for.
Okay, just give it up are you serious? It recirculates exhaust gases. It has no control over temperature whatsoever, that is the result of having the valve
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  #14  
Old 06-29-2009, 11:22 PM
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GregWeld GregWeld is offline
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FIGHT!

LOL

The whole thread wasn't about EGR -- it's about PCV and it's use or lack thereof...

Now you two go back to your rooms and don't come out until you can be nice!!
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  #15  
Old 06-30-2009, 03:21 AM
BritishGreen68 BritishGreen68 is offline
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Check into it and you'll see that it's not what "I think" EGR is for, but what it actually is for.
5 seconds on Google----
The EGR valve helps your car more efficiently and completely burn fuel by recirculating a portion of your exhaust and running it through the combustion process again. This results in a cooler, more complete burn of the fuel which decreases you car's noxious emissions by prohibiting the formation of some harmful gases.
The EGR valve, or Exhaust Gas Recirculation valve, is a vacuum controlled valve which allows a specific amount of your exhaust back into the intake manifold. This exhaust mixes with the intake air and actually cools the combustion process. Cooler is always better inside your engine. The exhaust your EGR valve recirculates also prevents the formation of Nitrogen related gases. These are referred to as NOX emissions, and are a common cause for failing emissions testing. Unfortunately, your EGR valve can get stuck, causing NOX gases to build up. You'll know if your EGR valve is stuck or malfunctioning because your car will experience symptoms like rough idle and bucking on accelertaion.
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  #16  
Old 06-30-2009, 10:22 AM
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Okay, just give it up are you serious? It recirculates exhaust gases. It has no control over temperature whatsoever, that is the result of having the valve
@ OLDS

I think you needed to do a bit of research on the subject BEFORE starting a cat fight... LOL

I love stuff like this - because it causes me to go out and RESEARCH the subject... to my surprise (NOT!) I usually learn something in the process.
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  #17  
Old 06-30-2009, 10:40 AM
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okay, then this is directed toward all of you because I'm guessing you don't understand how chemistry or physics work

Let me introduce or refresh a new concept to you all. You can boil water without heat, you use pressure. The two are directly related but not interchangeable.

Now, if you have a valve that controls vacuum - pressure - of exhaust gasses you are not varying temperature in any way. When the valve opens as more fuel is being put into the engine (and coming out), the pressure of exhaust gases decreases and it has a similar effect as lowering temp. BUT there is no temperature regulation or change.

It has NO direct effect on exhaust gas temperatures. There is no possible way that a vacuum which controls pressures can be regulated by temperature. Because the properties are directly related, it has the same effect and it's easier for people who can't explain it to say --- oh it lowers exhaust temperatures.

So before you all start saying I don't know my stuff, you better think about it for a while.
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Old 06-30-2009, 01:28 PM
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Originally Posted by olds View Post
okay, then this is directed toward all of you because I'm guessing you don't understand how chemistry or physics work

Let me introduce or refresh a new concept to you all. You can boil water without heat, you use pressure. The two are directly related but not interchangeable.

Now, if you have a valve that controls vacuum - pressure - of exhaust gasses you are not varying temperature in any way. When the valve opens as more fuel is being put into the engine (and coming out), the pressure of exhaust gases decreases and it has a similar effect as lowering temp. BUT there is no temperature regulation or change.

It has NO direct effect on exhaust gas temperatures. There is no possible way that a vacuum which controls pressures can be regulated by temperature. Because the properties are directly related, it has the same effect and it's easier for people who can't explain it to say --- oh it lowers exhaust temperatures.

So before you all start saying I don't know my stuff, you better think about it for a while.
@ Olds

Cut and pasted this from an article in EGR systems... there is much more detail about the systems for later vehicles etc - but for now - this states quite clearly what the EGR system does... regardless of whether or not the valve itself operates by vacuum doesn't really matter for purposes of this "argument":

Understanding Exhaust Gas Recirculation Systems

Posted 11/5/1997
By Henry Guzman
Exhaust gas recirculation (EGR) systems were introduced in the early '70s to reduce an exhaust emission that was not being cleaned by the other smog controls. Oxides of nitrogen (NOx) are formed when temperatures in the combustion chamber get too hot. At 2500 degrees Fahrenheit or hotter, the nitrogen and oxygen in the combustion chamber can chemically combine to form nitrous oxides, which, when combined with hydrocarbons (HCs) and the presence of sunlight, produces an ugly haze in our skies known commonly as smog.

How to reduce NOx NOx formation can be reduced by:

Enriching the air fuel (A/F) mixture to reduce combustion temperatures. However, this increases HC and carbon monoxide (CO) emissions.
Lowering the compression ratio and retarding ignition timing; but this leads to reduced performance and fuel economy.
Recirculating some exhaust gases.
How EGR systems work The EGR valve recirculates exhaust into the intake stream. Exhaust gases have already combusted, so they do not burn again when they are recirculated. These gases displace some of the normal intake charge. This chemically slows and cools the combustion process by several hundred degrees, thus reducing NOx formation.

The design challenge The EGR system of today must precisely control the flow of recirculated exhaust. Too much flow will retard engine performance and cause a hesitation on acceleration. Too little flow will increase NOx and cause engine ping. A well-designed system will actually increase engine performance and economy. Why? As the combustion chamber temperature is reduced, engine detonation potential is also reduced.
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  #19  
Old 06-30-2009, 01:54 PM
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Originally Posted by GregWeld View Post
regardless of whether or not the valve itself operates by vacuum doesn't really matter for purposes of this "argument":

How EGR systems work The EGR valve recirculates exhaust into the intake stream. Exhaust gases have already combusted, so they do not burn again when they are recirculated. These gases displace some of the normal intake charge. This chemically slows and cools the combustion process by several hundred degrees, thus reducing NOx formation.
.
Okay, I've been trying to tell you it doesn't reduce exhaust temp. And for the last time tell me how this reduces exhaust gas temperatures?

Here's what you can do if you don't believe me, take a nice high dollar probe and stick it in your exhaust pipe, you can even use a fitting if you like. Take the temperature when the EGR valve is closed, the exhaust will be temp A.

Take the reading when the EGR valve is open, it will be temp A.

Recirculating gases and reducing pressure out your exhaust does not cool it in any way.
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  #20  
Old 06-30-2009, 04:45 PM
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Originally Posted by olds View Post
Okay, I've been trying to tell you it doesn't reduce exhaust temp. And for the last time tell me how this reduces exhaust gas temperatures?

Here's what you can do if you don't believe me, take a nice high dollar probe and stick it in your exhaust pipe, you can even use a fitting if you like. Take the temperature when the EGR valve is closed, the exhaust will be temp A.

Take the reading when the EGR valve is open, it will be temp A.

Recirculating gases and reducing pressure out your exhaust does not cool it in any way.
@Olds --

Let's try this one last time... because EVERYTHING I read about EGR systems say the same thing - they are present in diesel and gasoline engines because THEY REDUCE TEMPERATURES... Whether you choose to believe it or not matters little to me. I never knew what they were for until this thread started - and you started to argue about it. So... like I always do... I went out and researched what this system does.... and I learned a couple of things. #1 is that this system is in place to REDUCE TEMPERATURE... #2 is that, as usual, I never trust what anyone blindly states on the internet - and especially in a forum... because many people just think they know - and often times they're just plain wrong.

So here's how the EGR system reduces temperatures :

Exhaust gas recirculation

In internal combustion engines, exhaust gas recirculation (EGR) is a nitrogen oxide (NOx) emissions reduction technique used in most petrol/gasoline and diesel engines.
EGR works by recirculating a portion of an engine's exhaust gas back to the engine cylinders. Intermixing the incoming air with recirculated exhaust gas dilutes the mix with inert gas, lowering the adiabatic flame temperature and (in diesel engines) reducing the amount of excess oxygen. The exhaust gas also increases the specific heat capacity of the mix, lowering the peak combustion temperature. Because NOx formation progresses much faster at high temperatures, EGR serves to limit the generation of NOx. NOx is primarily formed when a mix of nitrogen and oxygen is subjected to high temperatures.

So I think that TEMPERATURE REDUCTION is mentioned TWICE in just this one description of it's function. Vacuum isn't... that seems to be just a controller function and varies widely depending on the system.

Class is over on this one.
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