S52 OBD1 - Bucking... MAF or ... ? Help!

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  • Tekals
    Noobie
    • Nov 2012
    • 24

    #1

    S52 OBD1 - Bucking... MAF or ... ? Help!

    Hi,

    I've swapped an S52 OBD1 into my e30 in August. Engine has had a few things done to it beside the OBD1 conversion. Dinan throttle body, M50 intake, euro 3.5" MAF, sharks injectors, Dinan computer and tune. I've also changed the spark plugs and new crankshaft position sensor.

    Motor ran fine for a while then i started having heavy bucking (like the engine cuts out completely for a fraction of a second) when hitting potholes and just became worse with time eventually became undrivable. Disconnected the MAF and the car has been running fine but really rich.

    I've purchased a new MAF as I thought it was my problem. Changed it, but it didn't fix the bucking issue. I've started thinking what else changed after the swap. The headers didn't fit so I had a custom exhaust made and they relocated the oxygen sensor. It used to be after the downpipe only picking up 3 cylinders. Now it is much further back (middle car) and is right at the H pipe intersection. Could this affect the signal and cause issues??

    Any ideas? Diagnosis tests suggested?

    Thanks guys.
    Last edited by Tekals; 10-20-2016, 07:52 PM.
  • Poopie
    Wrencher
    • Jun 2009
    • 295

    #2
    Could be bad grounds. My bucking issues are from the disintegrating maf connector.

    Comment

    • Jaker
      Wrencher
      • Oct 2013
      • 234

      #3
      Originally posted by Poopie
      Could be bad grounds. My bucking issues are from the disintegrating maf connector.
      Do you know this for sure? Have you fixed/replaced the connector and the issues went away? My MAF connector has seen better days, but didn't think the issues I'm having were because of the connector. My issues are only when the engine/engine bay are cold. Once things warm up, the car drives fine.

      Comment

      • Tekals
        Noobie
        • Nov 2012
        • 24

        #4
        I can confirm my MAF connector is perfectly fine. might have to follow the wires and look for a bad connection maybe. It could explain why it started by bucking only when hitting bumps in the road

        Comment

        • sweet3
          Mod Crazy
          • Oct 2012
          • 749

          #5
          I just posted this is someone else's post as well. They were also having problems that might be related to the mad.
          If you have a K&N filter or something similar, try put the MAF sensor connector on the top and see what happens. Seemed to do the trick for me.
          PNP Adapter Harness Wiring for M52TU, M54, S54, M60, M62, M62TU, S62, M50, S50, M52, S52 & MORE

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          • Tekals
            Noobie
            • Nov 2012
            • 24

            #6
            Originally posted by sweet3
            I just posted this is someone else's post as well. They were also having problems that might be related to the mad.
            If you have a K&N filter or something similar, try put the MAF sensor connector on the top and see what happens. Seemed to do the trick for me.
            Tried that, seems to have helped a bit but didn't solve the issue, thanks tho

            Comment

            • sweet3
              Mod Crazy
              • Oct 2012
              • 749

              #7
              Ah, have you tried cleaning it since you had it the other way? Spray some brake cleaner and blow it with air. Don't let the brake cleaner sit too long though.
              Just pulling at straws now lol. This might not make any difference.
              Hope you get it figured out.
              PNP Adapter Harness Wiring for M52TU, M54, S54, M60, M62, M62TU, S62, M50, S50, M52, S52 & MORE

              sigpic

              Comment

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