boost figures, wastgate settings

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  • vagrallye
    S2Forum Enthusiast
    • Dec 2008
    • 157
    • Home: England Current: United Kingdom

    #1

    boost figures, wastgate settings

    i have just removed a "super chips" chip to fit a "pair" of mrc hi boost chips on a 3b s2, i have set the wastegate back to where i concider it to be correct (super chips chip relied on tightening the spring from what i can make out)
    just wanna make sure im in the right place

    i am talking about guage readings below
    may be a silly question but the mrc chips are a 1.3bar map
    does this mean they hold 1.3bar or peak 1.3bar (19psi)
    what pressure are people seeing with mrc chips on an 3b s2?
    i think im not quite right on the waste gate as i retested with super chip after winding screw out to cover the " un tarnished " threads and i saw 9-10psi and holding quite well, i was lead to believe stock pressure is 0.5 bar /7psi
    so i could be 3 psi out or i could be a percentage out
  • 4WheelDrifter
    S2Forum Zealot
    • Oct 2004
    • 5773
    • Country: Devon

    #2
    IIRC with the N75 unplugged you should get 0.4 bar boost. Check that and adjust the spring tension first. Plug the N75 back in, reset the ECU, you should then get 1.4 bar boost with the MRC chips.
    SS

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    • vagrallye
      S2Forum Enthusiast
      • Dec 2008
      • 157
      • Home: England Current: United Kingdom

      #3
      Originally posted by 4WheelDrifter
      IIRC with the N75 unplugged you should get 0.4 bar boost. Check that and adjust the spring tension first. Plug the N75 back in, reset the ECU, you should then get 1.4 bar boost with the MRC chips.

      ill do that , how do i reset ecu? can it be done without scanner etc i would of thought it would be semi self learing being old digifant style , just left a code but worked fine...?
      how come 1.4 bar on a 1.3 bar chip set? is this a "peak/spike" or steady figure?

      Comment

      • 4WheelDrifter
        S2Forum Zealot
        • Oct 2004
        • 5773
        • Country: Devon

        #4
        If you've got a 1.3 bar chip then you'll get 1.3 bar peak. The boost will then slowly tail off towards the redline.
        Just reset the ECU by leaving the battery disconnected for a few seconds.
        SS

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        • vagrallye
          S2Forum Enthusiast
          • Dec 2008
          • 157
          • Home: England Current: United Kingdom

          #5
          Originally posted by 4WheelDrifter
          If you've got a 1.3 bar chip then you'll get 1.3 bar peak. The boost will then slowly tail off towards the redline.
          Just reset the ECU by leaving the battery disconnected for a few seconds.
          cool ,thanks i couldnt of been far out when i wound back the spring then, ill redo it , i couldnt remember stock figures ant then couldnt remember how to calculate to psi
          but i know know, ill set to 6/7psi with valve disconected then disconect battery and go from there,


          could it be a stiffer spring also from super chips????

          Comment

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

            #6
            Or pull the 2 "Motor" fuses at the front of the fuse box.

            S2 Coupe 3B Project


            Ur quattro restoration

            S2 Avant

            Boost is the new rock and roll!
            sigpic

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            • 4WheelDrifter
              S2Forum Zealot
              • Oct 2004
              • 5773
              • Country: Devon

              #7
              Originally posted by vagrallye
              cool ,thanks i couldnt of been far out when i wound back the spring then, ill redo it , i couldnt remember stock figures ant then couldnt remember how to calculate to psi
              but i know know, ill set to 6/7psi with valve disconected then disconect battery and go from there,


              could it be a stiffer spring also from super chips????
              It's worth checking the spring. See this thread for details of the stock spring.

              Good point Newsh. I forgot about those 'motor' fuses.
              SS

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              • vagrallye
                S2Forum Enthusiast
                • Dec 2008
                • 157
                • Home: England Current: United Kingdom

                #8
                how mush thread should be showing either inside the nut of outside the nut on the top of the wastegate? anyone got any pics of stock wastegate showing this?

                Comment

                • UrS4boy
                  S2Forum Obsessed
                  • Feb 2006
                  • 11859
                  • Country: Canada

                  #9
                  Originally posted by vagrallye
                  how mush thread should be showing either inside the nut of outside the nut on the top of the wastegate? anyone got any pics of stock wastegate showing this?
                  Proper wastegates do NOT have bolts with nuts sticking out of the middle of them. They have a hex (Allen) socket-headed bolt that sits down IN the wastegate. Stock has the top of the socket-headed bolt down about 3 or 4 threads IIRC.

                  I am running a 1.9 bar WG spring and have to have the socket-headed bolt run right to the top because otherwise the rate of boost rise is too much for the ECU and it thinks it is overboosting and goes into a reduce boost/increase boost jerk/coughing session.
                  RS2'd 93 UrS4 5 spd sedan
                  94 UrS4 V8 6 spd manual avant

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                  • vagrallye
                    S2Forum Enthusiast
                    • Dec 2008
                    • 157
                    • Home: England Current: United Kingdom

                    #10
                    i need to check the spring then by the sounds of things , i also have a misfire problem whish could be assosiated to making to much boost to quick!

                    the boost chip in the ecu was deffo standard so the super chip must rely on bigger spring or tightening it up
                    ill check today
                    i thought i saw on here some pics of standard springs but i cant find it now any pics or ideas where the post is?
                    cheers

                    Comment

                    • Rusty
                      Super Moderator
                      • Jun 2004
                      • 18953
                      • Country: United Kingdom

                      #11
                      With the N75 unplugged the gauge pressure should be 0.4 bar. Adjust the pre-load bolt on the spring to achieve this and then as said above, it should all work a lot better. Nothing wrong with mechanical boost IMO but it has to be done properly and Motronic isn't the answer.
                      Cheers'en, AndyC
                      1994 ABY Coupe - Projekt Alpinweiss

                      Comment

                      • vagrallye
                        S2Forum Enthusiast
                        • Dec 2008
                        • 157
                        • Home: England Current: United Kingdom

                        #12
                        gonna check the spring first cause if its a stiffer spring im fighting a loosing battle

                        Comment

                        • 4WheelDrifter
                          S2Forum Zealot
                          • Oct 2004
                          • 5773
                          • Country: Devon

                          #13
                          Originally posted by vagrallye
                          i need to check the spring then by the sounds of things , i also have a misfire problem whish could be assosiated to making to much boost to quick!

                          the boost chip in the ecu was deffo standard so the super chip must rely on bigger spring or tightening it up
                          ill check today
                          i thought i saw on here some pics of standard springs but i cant find it now any pics or ideas where the post is?
                          cheers
                          It sounds like the usual Superchips setup. Many 'chip tuners' don't even know how to write a boost chip, so they rely on messing with the wastegate spring to adjust boost. The fuel and ignition chip probably has some maps that they 'borrowed' from somewhere else.
                          A good reason to ditch them in favour for some decent ones like MrC chips.

                          Check the link in my previous post for info on stock wastegate springs.
                          SS

                          Comment

                          • vagrallye
                            S2Forum Enthusiast
                            • Dec 2008
                            • 157
                            • Home: England Current: United Kingdom

                            #14
                            Originally posted by 4WheelDrifter
                            It sounds like the usual Superchips setup. Many 'chip tuners' don't even know how to write a boost chip, so they rely on messing with the wastegate spring to adjust boost. The fuel and ignition chip probably has some maps that they 'borrowed' from somewhere else.
                            A good reason to ditch them in favour for some decent ones like MrC chips.

                            Check the link in my previous post for info on stock wastegate springs.
                            cheers , yea im glad i got mrc chips

                            Comment

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