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Discussion Starter · #1 ·
My secondary air pump is out the window. During the last winter is was filled of water and frozed. When I openned it, the bearing were for the birds. Is it a problem not to replaced it, worth about 435 CAN$. My understanding, it is a secondary feature for pollution controle when the engine is cold, and do not afect any system of the car. The main disadventage that I see currnetly, is that the engine ligth will always be on, with the related message on the display screen. Any tips to turn of the engine light off permenantly for this specific engine code.
 

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Exhaust pressure will push that water you found in the secondary air pump up into to air box via the inlet hose. Yes, you could plug everything up before the exhaust gas gets into the plastic tubing, but it some point it will have to be fixed. Changing out the combination valve isn't too difficult, the air pump I found to be a lot more work. If you haven't already, change out your vacuum hoses as well.
 

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Discussion Starter · #3 ·
What do you mean plug everthing up. Secondly, the pump does not have a device to prevent the air / water to go back to the air box isnt one way.

Also It is possible to remove the pump from the bottom, took me 1 hours back and forth.
 

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GGregg said:
What do you mean plug everthing up. Secondly, the pump does not have a device to prevent the air / water to go back to the air box isnt one way.

Also It is possible to remove the pump from the bottom, took me 1 hours back and forth.

What I mean is devise a way to keep exhaust gas from traveling past the combination valve in it's path toward the air pump. A solid metal plate, for instance. Having (hot) exhaust gases enter plastic tubes is not safe.
I'm surprised VW wants to assume the carbon monoxide liability and not extend the warranty on these secondary emission system prone to failure parts.

I ignored my codes for quite a while. Almost by accident I discovered sooty water on "top" of my air filter. A byproduct of gasoline combustion is H2O. If the combination valve is not working correctly it allows exhaust gas to enter the tube all the time - not just when the pump is working. Now, of course, if the pump is working correctly, it's pressure is greater than the exhaust pressure and the air pump "air" enters the exhaust stream. Start up emissions are reduced, everyone is happy.

With a faulty combination valve over time water accumulates in the tubes going into and out of the air pump. In my case eventually the exhaust pressure (under boost?) pushed sooty water collected in the tubes and air pump into the air box. What you get in this instance is unfiltered dirty water entering the intake. I had already replaced my MAF once, I didn't want to do it again, so broke down and ordered the replacement parts.

You're a better mechanic than I am. I spent hours on that part of the project! Hopefully the new replacement combination valve will last longer than the OEM.
 

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Discussion Starter · #5 ·
So you wont concider to plug the pump outlet as a permanent fix. I think that it will save the MAF. By the way, I also have a faulty code with the MAF, I concider cleaning it very soon. I will also verify the combinaison valve very soon. I will let you know of my findings.

By the way do you know how to paste figure, I have the diagram of the segondary injection pump but I am not able to paste it. There is still something that I can not understand. On the diagram the outlet of the pump goes to the combinasion valve than go to the secondary injection valve close the intake manifold, but there is no connection to the exhaust??

The diagram ( Fig.86 )I am talking about can be found in the PDF files at this link.

Thanks in advance

GGregg

http://1.8t.org/~tabamoura/manual/aeb.atwengine.pdf
 

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If you were to disconnect any of the tubing and start the engine you would have exhaust gases coming out. This is the source of the sooty water in your secondary air pump.

It's a domino effect. If the combination valve fails and sticks open then when the air pump is not running (and it's off 99.5% of the time) it fills with sooty exhaust. The water vapor in the exhaust condenses and forms water. The water over time destroys the electric air pump. Now you have two things to replace.
 
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