EGR Removal and Hose Delete Assistance

[flashburn]

I've removed my EGR valve while prepping for my GT28 install and I have some questions for the masters. I attached a photo at the end of this post to make sense of some things.

The large breather hose connected to the EGR which makes a T fitting with the crank case breather I was planning on running to a catch can. Yes - good idea? (See red handled pick)

The small vacuum line which was connected to the EGR I was going to plug. I'd like to just remove it but I see it connects to the solenoid under the intake manifold. What should I do, plug or cut? (See middle finger pointing at it)

Finally, I have to admit defeat and mention that I do not know what the third hose in the picture powers, other than it was connected to the turbo inlet pipe so I imagine it needs vacuum. (See index finger pointing at it)

[texasboy21]

The Audi B6 does not have an EGR valve.

SEARCH noob - http://www.audizine.com/forum/showth...ht=vacuum+line

http://www.audizine.com/forum/showth...simplification

[Charles.waite]

^^ This. WE have no EGR. So before you start removing things whose function you don't know, do some research.

[hanzy]

There is EGR, just no EGR valve.

Internal EGR...

[old guy]

There is EGR, just no EGR valve.

Internal EGR...

It's not an internal EGR. There are no exhaust gasses being recirculated. The combi valve simply adds extra O2 to the exhaust stream to combine with the 22° of intake cam advance. This helps burn more of the A/F mixture that gets pushed downstream because of the advance. End result is faster heat up for the cat.

Chapter 2.1.3 Clicky click

[flashburn]

SAI/EGR - are we really going to argue over that? In the write up itself it says "EGR" so I think there is room for error here. This is my first SAI or EGR related repair or removal so I'm looking for some assistance.

Anyhow: That IS the write up I have read through many times and have been following, I've removed the SAI system as per the write up. I'm planning on keeping the N75 valve in the system for tuning purposes.

Can anyone help in answering my questions about what to do with the hoses? I'm not removing the crankcase breather hoses under the intake manifold. (OR IS THIS MY FOLLY AND I SHOULD JUST COMMIT) I'm thinking of running the mysterious vacuum line back down the valve cover where it was to the new TIP and blocking off the vacuum line that was running to the SAI. I still can't make sense of what the mysterious vacuum line was powering as I can't follow it under the intake manifold.

[Charles.waite]

Oh lord. Those DIYs just need to be deleted. So much disinformation. Just enough rope for most people to hang themselves.

OP: why are you deleting these?

[walky_talky20]

To put aside the "why are you doing this? Think of the children!" for just a moment, I will - at risk of a public flogging - answer the OP's questions:

A: The large breather hose connected to the EGR which makes a T fitting with the crank case breather I was planning on running to a catch can. Yes - good idea? (See red handled pick)

The hole you plugged with your pick tool was not connected in any way to the SAI system at any time...ever. You are getting confused between the 2 large metal hard lines that originally ran across the side of the valve cover. They are completely separate systems: PCV (nasty fumes) and SAI (fresh air!). If you want to put catch can in between that 3-way breather hose and the PRV, while still leaving it connected to the TIP, that's not a bad idea. Just make sure nothing leaks.

B: The small vacuum line which was connected to the EGR I was going to plug. I'd like to just remove it but I see it connects to the solenoid under the intake manifold. What should I do, plug or cut?

You should plug. If you leave it open, you create a vacuum leak whenever the SAI would normally be active. And vacuum leaks are bad. Just trust me on that one.

C: Finally, I have to admit defeat and mention that I do not know what the third hose in the picture powers, other than it was connected to the turbo inlet pipe so I imagine it needs vacuum.

The 3rd hose is a metered fresh air supply from the turbo inlet pipe to the Suction Jet Pump. It supposedly helps your brakes work better. I'd suggest you hook it up to the TIP, unless you want to actually delete the suction jet pump itself.

I hope the above sheds some light on the various modifications you dove into there. Good Luck with all that.

[old guy]

Excellent work as always WalkyT

flashburn: My point wasn't to correct the nomenclature of the device. My point was to educate you as to what it does not what it is called. I am amazed that anyone would decide to just start removing stuff from their motor without having a clue as to its function.

Do you really need all those extra lines coming off of your ABS module? Looks like a good candidate for hydraulic simplification to me. It would really clean things up under the hood and look a lot neater. And as an added benefit there would probably be a little weight savings to boot!

[diagnosticator]

It is hard to advise someone when that person is so clueless about the system they want information about. First, you need to be on the same page with those who know what they are talking about. Then the advise has relevance. If you are resistant to learning what the components are actually installed to do, it becomes difficult to advise you properly in regards to your questions. For what it's worth, the AMB 1.8T does employ EGR, but that is a result of the valve timing overlap and the pressure differentials existing between the intake and exhaust manifolds. This is called Internal EGR. When the stock parts are changed, like a different turbo and exhaust system, the resulting internal EGR rate will change as well, either more or less exhaust recirculation compared to the expected amount. This will effect the air/fuel mixtures that must be used, for best power and drivability. Without understanding this aspect, optimum results are very unlikely to be realized. I don't know of any tuners or DIY tuners using software like Maestro or similar who have any idea how the internal EGR effects the tuning they are trying to employ. EGR has a major influence on how the engine runs especially with the effects on drivability and torque production. I have never heard of any tuner discussing this important part of the many factors involved with changing the ECU tune. Therefore no matter how much the tuner thinks they know about what is happening, in reality, they are only guessing what is going on inside the engine in response to changed tuning parameters.

Good luck with this.

[old guy]

External EGR uses a valve that allows exhaust gases to enter the combustion chamber in order to reduce peak temperatures to keep NOx emissions down.

Internal EGR makes use of the valve overlap period to regulate how much exhaust gas still remains in the cylinder during the combustion process. Obviously you need variable cam timing to make this happen. The end result is to reduce peak temperatures to keep NOx emissions down.

That is not the same function as the SAI system on the 1.8T. With the SAI system the intent is to increase the temperature in the cat faster than would occur normally. I agree that part of the system functions with the same mechanism as an internal EGR. With that being said an internal EGR is used for cylinder temperature reduction to reduce NOx emissions. The SAI system uses the valve overlap to move the A/F mix more toward the exhaust stream and then injects a high volume of air to get it to burn hotter as it enters the front catalyt section of the catalytic converter. The primary function is to reduce emissions during the first few seconds of a cold start. The link provided above in post #5 gives a very detailed discussion of the development and implementation of the SAI system.

[diagnosticator]

External EGR uses a valve that allows exhaust gases to enter the combustion chamber in order to reduce peak temperatures to keep NOx emissions down.

Internal EGR makes use of the valve overlap period to regulate how much exhaust gas still remains in the cylinder during the combustion process. Obviously you need variable cam timing to make this happen. The end result is to reduce peak temperatures to keep NOx emissions down.

That is not the same function as the SAI system on the 1.8T. With the SAI system the intent is to increase the temperature in the cat faster than would occur normally. I agree that part of the system functions with the same mechanism as an internal EGR. With that being said an internal EGR is used for cylinder temperature reduction to reduce NOx emissions. The SAI system uses the valve overlap to move the A/F mix more toward the exhaust stream and then injects a high volume of air to get it to burn hotter as it enters the front catalyt section of the catalytic converter. The primary function is to reduce emissions during the first few seconds of a cold start. The link provided above in post #5 gives a very detailed discussion of the development and implementation of the SAI system.

Is your post in response to my post? Not sure if I have confused the discussion somehow.

[old guy]

Nope. Just some general comments as to why the SAI isn't the same as an EGR (either internal or external). It seems to be a common misconception with the 1.8T.

[diagnosticator]

Nope. Just some general comments as to why the SAI isn't the same as an EGR (either internal or external). It seems to be a common misconception with the 1.8T.

Very true

[hanzy]

It's not an internal EGR. There are no exhaust gasses being recirculated. The combi valve simply adds extra O2 to the exhaust stream to combine with the 22° of intake cam advance. This helps burn more of the A/F mixture that gets pushed downstream because of the advance. End result is faster heat up for the cat.

Chapter 2.1.3 Clicky click

Oldyguy I am well aware that the combi valve is for SAI purposes only.

I was referencing the above comment that there is no EGR, when in fact there is internal EGR via valve over lap.

It would not even make sense(me saying the combi is an internal EGR valve) as it is obviously external...

[old guy]

Oldyguy I am well aware that the combi valve is for SAI purposes only.

I was referencing the above comment that there is no EGR, when in fact there is internal EGR via valve over lap.

It would not even make sense(me saying the combi is an internal EGR valve) as it is obviously external...

Mea Culpa, hanzy. I guess I was too wrapped up in the SAI/EGR confusion and wasn't comprehending that your were addressing the comment that the 1.8T has a VVT egr separate from the SAI start up cycle.


And if anyone wants to log block 91 I think they would be surprised at how active it really is. Unfortunately it isn't really "variable" in the true sense of the word. It's either on (+22°) or off (0°). Under full throttle pulls its typically on up to around 4,500 rpm and then returns to the zero setting beyond. I believe it also activates under coast down conditions.

[flashburn]

In re-reading my original posts I realized I combined the two systems when describing my problem to make it seem like I was completely lost. So my apologies there. I am familiar with the SAI system and it's functions. I mis-wrote out of emotion due to the circumstance since I got worried I got in over my head! Thank you walky for you description, I ended up just spending some very dedicated time to follow each hose and came to the same conclusions as you've just described. I needed to step back from the situation and re-examine what I was digging into. Once I got out of my own way and quit following write ups so blindly - I was able to problem solve what I had done.

I only removed the SAI system because I no longer have a cat and I wanted to simplify the TIP for my BT install. I appreciate everyone's response and apologize for the very misleading posts! I deserved the NOOB name calling and just had a very bad moment of panic.

Also, thanks for the explanatory links as they helped me retrace my steps.

[hanzy]

Mea Culpa, hanzy. I guess I was too wrapped up in the SAI/EGR confusion and wasn't comprehending that your were addressing the comment that the 1.8T has a VVT egr separate from the SAI start up cycle.


And if anyone wants to log block 91 I think they would be surprised at how active it really is. Unfortunately it isn't really "variable" in the true sense of the word. It's either on (+22°) or off (0°). Under full throttle pulls its typically on up to around 4,500 rpm and then returns to the zero setting beyond. I believe it also activates under coast down conditions.

Mea Culpa...have not heard that in awhile.

No worries.

Some good info in this thread.

Goodluck OP.