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Problems with idle and shuddering. Please help!

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  • Problems with idle and shuddering. Please help!

    Hey all

    My M has decided to stick at around 1300 rpm when idling and then drop down to normal and then go back up again and so on. It also shudders a little when i'm driving at a constant speed.

    BMW put it on diagnostics and it showed nothing but I took their engineer for a spin and he witnessed the fault.

    He suggested changing the accelerator switch (whatever that is) which I did for the princly sum of £110. It worked for about a week and now the problem is back.

    Any ideas?

    I was thinking it may be a fuel issue but I always use Optimax so it shouldn't be. I let it run down to below a quarter of a tank and then tried some Esso super unleaded but it has made no difference.

    Please help guys.
    Ex-z3mc Estoril
    Ex-Z4MC - carbon black
    Now - z3mc silver, minted

  • #2
    Are you covered under warranty?

    If you are not then I suggest you do not change things under trial and error but to actually try and plug in the diagnostics equipment when the fault is actually happening. I know with intermittent faults this is difficult but in the long run might save you some money.

    Saying that I had a similar problem on an E36 M3 and it turned out to be the one of the oxygen sensors. This was after I had changed the coils and a mutlitude of sensors.

    Cheers

    Greenbat

    Ex MC Owner

    Comment


    • #3
      Hi Outrun,

      Congrats on the new MC. I am anew owner (s50) too and mine does the very same thing. It feels like you are running out of petrol and then picks up again. Mine usually does it when sat about 30-40 in 4th or 5th with little trottle. Drives me mad. Got mine into an indy on Friday for other stuff so will ask him to have a look. I'll let you know the outcome. Does yours seem to bog down when using the gearing to slow down (taking foot off the gas) when the aircon is on. I have noticed mine doing that too.

      Does yours also rev very high when you are starting from cold. Mine does and i have to blip the throttle and this usually solves the problem. I have a feeling all these problems are related.


      Good luck

      DAve
      EX: S50 Black with Kyalami Orange/Black Leather. Becker Bluetooth/Ipod HU.
      Now: S50 Black/Black with Ap Racing brakes and Race logic

      Comment


      • #4
        Thanks for the replies guys.

        Please keep me in touch with your outcome David.

        I've been advised that it could be some vacuum hoses that connect into the air filter box. I'm told
        these suffer from splits and give air flow issues.

        I'll get it checked inthe next week or two and post the outcome.

        Cheers
        Ex-z3mc Estoril
        Ex-Z4MC - carbon black
        Now - z3mc silver, minted

        Comment


        • #5
          Had a simular problem a few weeks ago
          If you look down the list to High revs when starting
          The vacumn hose under the inlet manifold and the blanking piece had split
          I had to remove the 90 degree pipe that connects the air filter box to the inlet manifold
          Down next to the dipstick tube is a vacumn pipe that goes into a Y piece one side goes to a valve the other has a blanking piece
          The vacumn tube and the blanking piece were both split
          Cost about £3.00 at local accessory store for some tube and a blanking piece
          Starts as normal and is smooth on constant runnig now.

          Comment


          • #6
            I wonder if some of these intermittent problems might relate to contamination of the MAF :?:

            I found this useful link about cleaning the MAF: http://www.louv.tv/cars/m5/MAF/
            /// Exdos ///
            "Men who try the impossible and fail spectacularly are infinitely superior to those who reach for nothing and succeed" --Napoleon Bonapart

            Comment


            • #7
              Cheers for the help again. I'm off to Northern Ireland on the Ferry with wife and dog (and BMW roof rails with carrier - looks well smart) on Friday. I'm intending on trying the fix with the vacuum pipes first next week. I'll post the results when I have done it.
              Ex-z3mc Estoril
              Ex-Z4MC - carbon black
              Now - z3mc silver, minted

              Comment


              • #8
                POSSIBLY A FAULT WITH THE IDLE REGULATING VALVE PART # 13411733090 :(

                Comment


                • #9
                  Too bad the old posts are gone, I wrote some posts about this.

                  In short: idle control potmeter / vanos valve / DME is what they replaced in my case :roll:


                  "Café-Racer mit Raketentrieb"

                  Comment


                  • #10
                    Hi Outrun,

                    have you had any closure on your idling problem?

                    cheers

                    David
                    EX: S50 Black with Kyalami Orange/Black Leather. Becker Bluetooth/Ipod HU.
                    Now: S50 Black/Black with Ap Racing brakes and Race logic

                    Comment


                    • #11
                      Just had mine fixed under EW ... was the MAF, changed it on the car (S54) and now she is perfect !
                      Need help setting up a CMMS/EAMS system?
                      S54: P*** Yellow ;-)

                      Comment


                      • #12
                        Originally posted by David1975
                        Hi Outrun,

                        have you had any closure on your idling problem?

                        cheers

                        David
                        Nope - he has sold the car to me and I have now experienced it first hand.

                        Drove to the airport on Tuesday morning - car started at "normal" revs at home. Pulled into the car park where the revs stuck at about 1300 rpm. Blipped the throttle, but no joy. Didn't have time to try work it out, so turned off and got my flight. Got back last night, turned the key - revs shot up to 1600 initially, blipped the throttle and they settled to around 1300 again. Left for home. Got the the queues at the Forth Road Bridge and "normal" idling had resumed.

                        I've not had a chance to look under the bonnet yet, but I am wondering whether a "sticking" throttle cable might be the cause? I don't know what the throttle mechanism is on the S50, but I had a similar problem on an old Corvette that I used to have and that turned out to be the cause.

                        Any thoughts anyone?
                        CLK55 AMG Cabriolet

                        ex Estoril Blue Z3M Coupe

                        Comment


                        • #13
                          Hmmm....I know I am probably clutching at straws here but last two tankfuls have been V Power (or whatever Optimax is called now) and problem is worse than ever. Prior to that, I've been using BP's Ultimate unleaded and things were fine on the whole. Will switch back when I next need to fill the tank and will report back. Very smooth under acceleration but lumpy/irregular idling :?:
                          CLK55 AMG Cabriolet

                          ex Estoril Blue Z3M Coupe

                          Comment


                          • #14
                            Is it just a problem at idle?

                            I had a similar sounding problem with my e36 328. When I changed gear and released the throttle, the revs would stay up where they were for a while, and when they did fall, it was all of a sudden with a bit of a 'jerk'. The revs sometimes climbed up by themselves when I was sitting in traffic.

                            I took the car to an indy to have a diagnostics check done, and it was the potentiometer. Changed this and it has been fine ever since.

                            Total bill including the diagnostics check was less than half thanexcess would be for an extended warranty claim.

                            Comment


                            • #15
                              Originally posted by biggusladdus
                              Is it just a problem at idle?

                              I had a similar sounding problem with my e36 328. When I changed gear and released the throttle, the revs would stay up where they were for a while, and when they did fall, it was all of a sudden with a bit of a 'jerk'. The revs sometimes climbed up by themselves when I was sitting in traffic.

                              I took the car to an indy to have a diagnostics check done, and it was the potentiometer. Changed this and it has been fine ever since.

                              Total bill including the diagnostics check was less than half thanexcess would be for an extended warranty claim.
                              Yeah the problem only appears at idle and is pretty much as described at the top of this message. Outrun did have the potentiometer replaced but the issue appears to have returned. I'll have to get it back in for a check and see what they come up with.
                              CLK55 AMG Cabriolet

                              ex Estoril Blue Z3M Coupe

                              Comment

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