Autocross in the morning and the car wont run. please help!!!

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  • Syncro325is
    E30 Addict
    • Mar 2009
    • 574

    #1

    Autocross in the morning and the car wont run. please help!!!

    car wont keep a steady idle, when driving it, it "hiccups" shoots a flame out the exhaust and then drives fine till the next hiccup(which are frequent). checked for vacuum leaks, and did not find any. wideband shows the AFR to be all over the place both rich and lean.
    sigpic
  • RickSloan
    R3VLimited
    • Feb 2008
    • 2401

    #2
    the vaccum gauge in the car is reading at 20 for a majority of the time when the car is running poor

    Need Illustration or Design work? www.robbiebyerly.com

    Comment

    • Adrian_Visser
      R3VLimited
      • Jun 2006
      • 2823

      #3
      Backfiring like that means unburnt fuel is going out the exhaust, I would do a compression test to see if there is a dead cylinder, even if it is still firing on all cylinders the compression could be low enough to not completely burn the charge and send it out the exhaust.

      '89 Alpine S52 with goodies

      Comment

      • Syncro325is
        E30 Addict
        • Mar 2009
        • 574

        #4
        no offense, but I really hope you're wrong.
        sigpic

        Comment

        • Adrian_Visser
          R3VLimited
          • Jun 2006
          • 2823

          #5
          could also be timing i suppose, the t-belt could have slipped a tooth or something

          '89 Alpine S52 with goodies

          Comment

          • Danny
            Moderator
            • Feb 2008
            • 14217

            #6
            Unplug the o2 sensor and run that fucker open loop.

            YEAHHHH DOGGY!

            Comment

            • RickSloan
              R3VLimited
              • Feb 2008
              • 2401

              #7
              no o2 doggy...

              Need Illustration or Design work? www.robbiebyerly.com

              Comment

              • Danny
                Moderator
                • Feb 2008
                • 14217

                #8
                I didn't actually know what to do.

                ... I just wanted to say yeah doggy.

                Comment

                • Syncro325is
                  E30 Addict
                  • Mar 2009
                  • 574

                  #9
                  Originally posted by Adrian_Visser
                  could also be timing i suppose, the t-belt could have slipped a tooth or something
                  Well I did do a T-belt recently, when I did my refresh. I was under the impression that because the m20 was an interference motor the valves would hit if it were off even the littlest.

                  BTW autocross was freaking awesome! I didn't get to drive my car, but I took Ricksloans 335...Yeah doggy!!!
                  sigpic

                  Comment

                  • jlevie
                    R3V OG
                    • Nov 2006
                    • 13530

                    #10
                    It would be a help to know what car this is. If one with an M20b25 engine (325i/is) I'd suspect the CPS, harmonic balancer, or something that is interrupting power to the DME.
                    The car makes it possible, but the driver makes it happen.
                    Jim Levie, Huntsville, AL

                    Comment

                    • Syncro325is
                      E30 Addict
                      • Mar 2009
                      • 574

                      #11
                      Originally posted by jlevie
                      It would be a help to know what car this is. If one with an M20b25 engine (325i/is) I'd suspect the CPS, harmonic balancer, or something that is interrupting power to the DME.
                      right, its an 87 m20b25 swapped into an 86 325es.
                      sigpic

                      Comment

                      • Syncro325is
                        E30 Addict
                        • Mar 2009
                        • 574

                        #12
                        Anyways the timing belt apparently is not the problem. Onward to harbor freight to get a compression tester...
                        sigpic

                        Comment

                        • Syncro325is
                          E30 Addict
                          • Mar 2009
                          • 574

                          #13
                          Here is a link to a video i made... Its not optimal because there is music and video from the autocross, but I don't want to upload another video. maybe someone will know what is wrong by the sound. idk i figured it may help. You can hear the sound my car is making past the video. Mines the black e30.

                          sigpic

                          Comment

                          • SpecM
                            R3V Elite
                            • Oct 2005
                            • 4531

                            #14
                            Hmm cam timing, or a sticky/bent valve

                            maybe?
                            1989 cirrisblau-metallic 325i

                            Comment

                            • Syncro325is
                              E30 Addict
                              • Mar 2009
                              • 574

                              #15
                              Originally posted by SpecM
                              Hmm cam timing, or a sticky/bent valve

                              maybe?
                              Cam timing is good...
                              sigpic

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