wont rev past 4k!!

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  • JayGotti
    Wrencher
    • Jul 2012
    • 200

    #1

    wont rev past 4k!!

    yea so my buddy has a e34 m50 single vanos and it doesnt past 4k under load. and revs to redline in neutral. ive read that it could be the cps but he replaced it and tht wasnt the problem. he also has a little leak on the manifold on the second piston area, could that be the cause of not revving past 4k under load?
  • evandael
    R3VLimited
    • Oct 2009
    • 2881

    #2
    did he wire up the VSS?

    Comment

    • JayGotti
      Wrencher
      • Jul 2012
      • 200

      #3
      Originally posted by evandael
      did he wire up the VSS?
      what is vvs?

      Comment

      • JayGotti
        Wrencher
        • Jul 2012
        • 200

        #4
        Originally posted by JayGotti
        what is vvs?
        you think the speed sensor could cause this?

        Comment

        • evandael
          R3VLimited
          • Oct 2009
          • 2881

          #5
          VSS is the vehicle speed signal. the M50's DME needs to see a road speed before it will allow it to rev past a certain RPM.

          i forget the c101 and x20 pin #'s but IIRC, this is a common cause for his issue.

          Comment

          • future rs
            E30 Addict
            • Aug 2012
            • 514

            #6
            Sounds like he is R3v limited...

            Comment

            • AlpineM325
              Grease Monkey
              • Aug 2007
              • 373

              #7
              Originally posted by future rs
              Sounds like he is R3v limited...
              Haha that it seems.

              WTB
              -convertible carpet, no rips, in socal.
              -s52, s50, m52, m54
              -harness, accessories, transmission

              Comment

              • JayGotti
                Wrencher
                • Jul 2012
                • 200

                #8
                Originally posted by evandael
                VSS is the vehicle speed signal. the M50's DME needs to see a road speed before it will allow it to rev past a certain RPM.

                i forget the c101 and x20 pin #'s but IIRC, this is a common cause for his issue.
                i have a 413 dme and if the vss doesnt work will the speedo work?

                Comment

                • e30rapidic
                  R3VLimited
                  • Oct 2003
                  • 2167

                  #9
                  vehicle speed sensor

                  ecu needs a signal from the back of the cluster. Lots of info on here regarding it
                  '87 325ic, powered by S50.

                  Comment

                  • JayGotti
                    Wrencher
                    • Jul 2012
                    • 200

                    #10
                    Originally posted by e30rapidic
                    vehicle speed sensor

                    ecu needs a signal from the back of the cluster. Lots of info on here regarding it
                    i was in his car trying to help him trouble shoot it and it basically acts like a 2step in gear. sometimes it passes 4k in first gear to like 5.5k, and sometimes in neutral it goes to redline and sometimes it does the 2step at 6 or 7k.

                    Comment

                    • JayGotti
                      Wrencher
                      • Jul 2012
                      • 200

                      #11
                      the signals from the c104 connector goes to the harness, are those 2 wires the vss? both tach and speedo work

                      Comment

                      • graphikg
                        Banned
                        • Jan 2008
                        • 1614

                        #12
                        Try disconnecting the vanos from the harness and driving it under load. If that allows the car to go past 4k, then it is Vanos and timing perhaps.

                        Comment

                        • JayGotti
                          Wrencher
                          • Jul 2012
                          • 200

                          #13
                          found the problem it was the vss thanks guys!!

                          Comment

                          • MaxBell
                            E30 Fanatic
                            • Oct 2010
                            • 1390

                            #14
                            Can you please post what you did to hook up the VSS? I heard it being said in various places and no one ever gives a SPECIFIC wiring tutorial.

                            What wire (color, location) did you start at? Which wire (color, location) did you connect to?

                            EDIT: Ok I got serious and pulled the wiring diagrams and things for my early model with a 1995 M50 in it.

                            Here you all go: http://www.r3vlimited.com/board/show...23#post3459423
                            Last edited by MaxBell; 11-13-2012, 08:50 PM.
                            REMEMBER: Be safe and have fun is Rule Number 1.

                            The Epic Unbuild of Clint Eastwood

                            Comment

                            • evandael
                              R3VLimited
                              • Oct 2009
                              • 2881

                              #15
                              what joy, a happy ending.

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