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  • S6 Boost Blues

    when i showed a friend of mine my new purchase, he gasped in horror when he saw this device:





    as i understand it, it's some kind of boy racer way of increasing boost pressure (sorry for my very limited understanding of this subject)
    anyway,i was advised to remove it and replace it with a plain section of hose:



    now, here's the problem: with the gizmo in place, the car would boost to 2.1 bar at approx 4000rpm and no higher regardless of revs. it's impressive to drive and pulls really well. reaching those revs and higher the car spits and coughs a bit. without the gizmo, the car is noticibly underpowered on acceleration and will only boost to around 1.3 bar and there is no misfire at all.

    when i got the car initially, quattrokid ran his vag com on it and it showed up with a few faults: ISV, engine speed sensor and n75 boost control valve (sorry, i can't remember the codes). now, with my crap knowledge is it safe to assume that the reason that the gizmo was fitted was to raise the boost pressure as there is a failure in the n75 boost control valve ie a cheapskate way of getting around buying a new n75 valve?



    any advice is greatly appreciated!!

    1997 Audi S6 - The Purple Helmet!

  • #2
    Get it of asap. It will not work with your ecu,you will get boost cuts. It looks like your n75 valve was unplugged ,and replaced with this bleed valve. Reconnect the n75 the correct way and you should see 2.1 on the digital boost gauge on the dash. Unless it has been mapped or has a different turbo then standard boost on the s6 is 1.1bar and a little more on overboost .the digital gauge is atmospheric and starts a 1bar, so 2.1 on the gauge is 1.1bar of boost. if you don't see this then you have a possible boost leak,
    and you need to do a boost leak test. There is plenty of information on hear if you do a search. Good luck

    Comment


    • #3
      I think your probably correct in thinking the bleed valve was fitted to get around a knackered (or misfitted) N75, 1.3 on your gauge is just 0.3 in real terms which is roughly what one would expect to see with the N75 unplugged. I suspect what your seeing boost wise is wastegate spring pressure only which should be 0.4 bar or 1.4 on your URS digital gauge.

      For the time being the car is much safer to drive it as is, don't be tempted to reinstate the bleed valve, make sure the N75 is fitted correctly (it's not that hard to get it wrong) and plugged in and if it's still not boosting purchase a new one, their not terribly expensive.
      1989 B3 2.0 3A 80 quattro... Budget 1.8T Project.
      1992 C4 100 2.8 Avant quattro... Mobile Sitting Room.
      1995 RS2... MTM K26/7 380 BHP Conversion.
      1990 Corrado G60... Breaking For Parts.

      Comment


      • #4
        thanks for that information, chaps. it's a whole new subject to me and i'm still trying to get my head around it.

        i called audi and they want £124.95 plus VAT for part no 034906283H n75 boost control valve!!!!!



        by any chance, does anyone have one for sale at a whole lot less than that??!
        1997 Audi S6 - The Purple Helmet!

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        • #5
          Get on eBay they come up quite often around the £50 mark

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          • #6
            Have you tried yours it maybe ok.

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            • #7
              Try Pete at Quattro Corner, TPS, Eurocarparts and a wanted ad on here....

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              • #8
                N75 Waste Gate Frequency Valve (WGFV) info

                Read this, it might help you figure things out:

                N75 Info from the Engine Bay Device Map

                RS2'd 93 UrS4 5 spd sedan
                94 UrS4 V8 6 spd manual avant

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                • #9
                  You might be able to get one here:
                  www.germanautopartsdirect.co.uk

                  Doesn't look like they have the H version for some reason, they have all the others.
                  Last edited by Colesy; 7 July 2014, 15:52.

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                  • #10
                    post it on the wanted section here.someone might be selling for cheap since they couldn't bear to see your old boost controller ;-)
                    one of a few I5 from Asia.

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                    • #11
                      and the s2 forum comes up trumps again - n75 on it's way soon!!

                      thanks!!

                      1997 Audi S6 - The Purple Helmet!

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                      • #12
                        Great stuff
                        96 URS6 plus speck saloon
                        96 URS6 plus speck estate
                        94 2.6 80 Avant
                        99 2.8 final edition Cabriolet

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                        • #13
                          I think, that they are not the same. H is stronger. In 034 Motorport is twice more expensive than the J version.
                          1-2-4-5-3

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                          • #14
                            Originally posted by igor136 View Post
                            I think, that they are not the same. H is stronger. In 034 Motorport is twice more expensive than the J version.
                            I thought the difference was just the orientation of the electrical connector?

                            Comment


                            • #15
                              Can you prove it? This is an interesting discussion.
                              1-2-4-5-3

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