N75 connection missing on RS2

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  • wowow
    S2Forum Enthusiast
    • Sep 2010
    • 123
    • Country: Hong Kong

    #16
    I read that Blow-off valve makes a nice woosh sound which my car does make a loud woosh whenever I shift up or back off the gas. However, they also cause loss in power and instead of re-circulating the air back into the system, it lets air go into the atmosphere. This causes the ECU to give too much fuel as it thinks air is still in the system. Am I correct ? Should I take out the Blowoff valve and go back to the Bypass ( cut-off valve ) ? Someone also suggest to upgrade the BPV to 0280142110
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    • newsh
      S2Forum Obsessed
      • Aug 2003
      • 16226
      • Country: United Kingdom

      #17
      So you've got 2 pipes on the WGFV, one is going to the lower chamber of the Wastegate, where does the other one go to?

      S2 Coupe 3B Project


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      • newsh
        S2Forum Obsessed
        • Aug 2003
        • 16226
        • Country: United Kingdom

        #18
        And yes, you need to go back to bypass valve.

        S2 Coupe 3B Project


        Ur quattro restoration

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        • wowow
          S2Forum Enthusiast
          • Sep 2010
          • 123
          • Country: Hong Kong

          #19
          Read some more on bypass valve vs blow-off valve ( http://www.audiforum.ca/showthread.php?t=382 ) I am damned !

          Right now, the "Blow-off valve" has a small hose leading towards the engine, and the other end towards the bottom of teh engine bay and I suppose that is connected to the cold side exit.
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          • prj
            S2Forum Zealot
            • Mar 2010
            • 6308
            • Country: Estonia

            #20
            Originally posted by wowow
            Read some more on bypass valve vs blow-off valve ( http://www.audiforum.ca/showthread.php?t=382 ) I am damned !

            Right now, the "Blow-off valve" has a small hose leading towards the engine, and the other end towards the bottom of teh engine bay and I suppose that is connected to the cold side exit.
            From the picture you already have a bypass valve, except the bypass is not connected so it is acting like a blow off.
            Your valve is probably fine, just connect a hose to it and fit it to an exit on a 45 degree angle towards the turbo inlet.
            You will probably have to make that exit in your plumbing.
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            • wowow
              S2Forum Enthusiast
              • Sep 2010
              • 123
              • Country: Hong Kong

              #21
              newsh, on the N75, one side is to the lower chamber of the wastegate, the other end is to the cold side of the turbo, right underneath the big air hose coming from the MAF. But looking at this diagram, I think my current N75 connection is wrong. The hose that connects to the cold side of the turbo should be connected to the "middle" nipple of the N75. Is that indication on the N75 to say which nipple goes where ? Or it doesn't matter ?

              I have problem finding the same diagram on VAGCAT 's RS2 section. I looked through all parts diagram under "engine"
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              • wowow
                S2Forum Enthusiast
                • Sep 2010
                • 123
                • Country: Hong Kong

                #22
                prj, my blow off valve has one small hose connecting to the engine ( towards the from grill ) and a 1" hose leading somewhere, and I suppose that is connected to the cold side exit. If I reconfigure it, is this how I should connect them to the BPV ( basspass valve ):

                1. side-tube connect to turbo cold side exit ( that is pull out the 1" hose from the blow-off valve and connect it to the side of the BPV )
                2. small hose connect to the big end of the BPV
                3. small end of BPV connect to the exit of MAF.

                Looking at the attached photo of the BPV, the side tube is connect to the exit of the MAF which is wrong.

                Am I correct ?
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                • wowow
                  S2Forum Enthusiast
                  • Sep 2010
                  • 123
                  • Country: Hong Kong

                  #23
                  found something similar to show how they are connected
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                  • s2_bo
                    S2Forum Zealot
                    • Oct 2005
                    • 6067
                    • Home: United Kingdom Current: France

                    #24
                    When i first looked at the picture i noticed that your DV (BPV) is not even looped in to the presure side of the intake, its just connected to the custom maf - turbo hose right?
                    So its doing nothing right now, and the noise your hearing is turbo chatter or compressor stall, what ever you want to call it. A sure way to kill the turbo.


                    It should be fitted like this:
                    The side large exit should go to the hose that runs from the cold side of the turbo to the intercooler.
                    The bottom large exit should be connected to the maf - turbo hose
                    The top small nipple connection should be connected to the front of your inlet manifold with a length of 3 or 4mm vacuum hose or silicone hose.


                    If its connected as above it will function properly, but at the moment its not doing anything..
                    91 S2 coupé - RIP
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                    • orangepeel
                      S2Forum Addict
                      • Feb 2011
                      • 205
                      • Country: United Kingdom

                      #25
                      yes thats right if it makes a howling noise when you put it back together . its ether needs a service kit as it may be caput or you may have put it on backwards

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                      • wowow
                        S2Forum Enthusiast
                        • Sep 2010
                        • 123
                        • Country: Hong Kong

                        #26
                        S2_bo, small nipple connect to the inlet manifold - as you can see from the attached photos, there is a small hose leading from the "blow off valve",and is now connected to the engine ( towards front grill - another photo ). Can I just pull this tube from the BOV and connect it to the small nipple on the BPV ?
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                        • s2_bo
                          S2Forum Zealot
                          • Oct 2005
                          • 6067
                          • Home: United Kingdom Current: France

                          #27
                          A stock DV (which i think this is, its just been spray painted silver) is not serviceable but the orientation is not really that important. The diaphragm inside still works the same even if the side and bottom exit connections are swapped over.
                          91 S2 coupé - RIP
                          98 S8 - Luxury barge

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                          • s2_bo
                            S2Forum Zealot
                            • Oct 2005
                            • 6067
                            • Home: United Kingdom Current: France

                            #28
                            Originally posted by wowow
                            S2_bo, small nipple connect to the inlet manifold - as you can see from the attached photos, there is a small hose leading from the "blow off valve",and is now connected to the engine ( towards front grill - another photo ). Can I just pull this tube from the BOV and connect it to the small nipple on the BPV ?

                            Im not quite sure what your saying because i thought we where referring to BOV and PPV as the same thing?


                            But yes, looking at your photo that connection is already ok, and you dont need to change it.
                            The hose is running to the metal pipe which runs towards the inlet manifold. If you look at the front of your engine near the grill (when its closed) there should be a short pice of pipe thats running from the inlet manifold (says Powered by Porsche on it ) to the metal pipe that then feeds towards the BOV or BPV or what ever.

                            So i think that connection for you is ok, (providing its connected on the inlet manifold side)

                            Im more intrested whats going on with the turbo to intercooler pipe and if the exit from that which should go to the BOV/BPV is there and blocked off.

                            Also, in the second photo, theres something connected to a vacuum pipe haven't seen that before. what is it?
                            91 S2 coupé - RIP
                            98 S8 - Luxury barge

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                            • orangepeel
                              S2Forum Addict
                              • Feb 2011
                              • 205
                              • Country: United Kingdom

                              #29
                              sorry bo i through he had an aftermarkit dv

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                              • s2_bo
                                S2Forum Zealot
                                • Oct 2005
                                • 6067
                                • Home: United Kingdom Current: France

                                #30
                                Ahhh.. i think i understand now
                                91 S2 coupé - RIP
                                98 S8 - Luxury barge

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