Why does my Boost fall?

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  • Lrutts
    Advanced Member
    • Sep 2010
    • 104

    #1

    Why does my Boost fall?

    What are the reasons that could cause my boost to hit 8psi then fall to 6 or 5 almost right away? I have an internal waste gate.
    Too small? Blood Sweat and Tears Build:
    http://www.r3vlimited.com/board/showthread.php?t=202389
  • MR 325
    Moderator
    • Oct 2003
    • 37828

    #2
    Leaky wastegate. Leaky boost pipes. Leaky BOV.
    BimmerHeads
    Classic BMW Specialists
    Grover Beach, CA

    www.BimmerHeads.com

    Comment

    • Dominic49
      E30 Fanatic
      • Feb 2007
      • 1373

      #3
      wastegate lag whats is the wastegate set to?

      exhaust piping, manifold design, there is alot of things at work here.

      Comment

      • bmw335isturbo
        Wrencher
        • Mar 2006
        • 218

        #4
        Originally posted by mr 325
        leaky wastegate. Leaky boost pipes. Leaky bov.
        +1

        1986 335is-1988 335ist -1991 335istsigpic

        Comment

        • Toadleg
          Wrencher
          • May 2011
          • 209

          #5
          sounds like a boost leak test is needed. In my experience if you look at your car wrong you will get a boost leak

          Comment

          • Lrutts
            Advanced Member
            • Sep 2010
            • 104

            #6
            Originally posted by Toadleg
            sounds like a boost leak test is needed. In my experience if you look at your car wrong you will get a boost leak
            Haha i would agree, ok thanks guys. I had a feeling that it was one of those things, but i figured i should ask incase there was something i missed. I will go tighten things up and then go from there.

            Whats the best way to test for a leak?
            Just doing the whole block off both sides and use an air compressor?
            Last edited by Lrutts; 07-17-2011, 01:00 PM.
            Too small? Blood Sweat and Tears Build:
            http://www.r3vlimited.com/board/showthread.php?t=202389

            Comment

            • Toadleg
              Wrencher
              • May 2011
              • 209

              #7
              On one of my cars I take the intake off the turbo and attach to that With whatever works for you size intake. For me it was a 2 inch mission band with pvc cap and thread in a schrader valve. Get a compressor and pump it up and you will hear the leaks or spray soapy water on pipes and bubbles will appear. You will have to cap off a couple lines that will just leak air I dont know your set up mine is one of those turbo neons.

              Comment

              • Toadleg
                Wrencher
                • May 2011
                • 209

                #8
                Try and get it to hold 15lb for as long as possible you will get some leak by in the head

                Comment

                • Toadleg
                  Wrencher
                  • May 2011
                  • 209

                  #9
                  On my car i switched to an external waste gate and that seemed to help with boost spike also

                  Comment

                  • sweet6e30
                    E30 Addict
                    • Feb 2011
                    • 531

                    #10
                    classic boost leak
                    my build here ---> http://www.r3vlimited.com/board/show...ht=lemans+blue

                    Comment

                    • ak-
                      R3V OG
                      • May 2009
                      • 12422

                      #11
                      Are you able to hear any faint rattling during boost?

                      1991 325iS turbo

                      Comment

                      • Lrutts
                        Advanced Member
                        • Sep 2010
                        • 104

                        #12
                        Originally posted by ak-
                        Are you able to hear any faint rattling during boost?
                        No it sounds fine, i can't even hear a wine or anything like that. I went to home depot to get the stuff i need to make a home made boost leak test kit, they had nothing.....
                        Too small? Blood Sweat and Tears Build:
                        http://www.r3vlimited.com/board/showthread.php?t=202389

                        Comment

                        • einstein57
                          R3V OG
                          • Jun 2007
                          • 10780

                          #13
                          Whats yor wastegate supposed to be set to?
                          Your signature picture has been removed since it contained the Photobucket "upgrade your account" image.

                          www.gecoils.com
                          My euro 316 project Transaction Feedback

                          Comment

                          • Lrutts
                            Advanced Member
                            • Sep 2010
                            • 104

                            #14
                            8psi, ebay turbo
                            Too small? Blood Sweat and Tears Build:
                            http://www.r3vlimited.com/board/showthread.php?t=202389

                            Comment

                            • euro2fast4u
                              Banned
                              • May 2009
                              • 545

                              #15
                              what size ebay turbo?

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