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  • Rough idle on start up?

    I have been having some car issues recently which I thought was down to a spark plug problem but a new set hasnt completely cured it , on start up when cold the car runs very lumpy and you can feel the shake through the car but when warm it appears to run ok and smooth, when oil is up to temp the tickover drops to 600 and no shake? . any ideas as although I know it could be one of many things.

    Many parts are new including most hoses and maf . I will try and get the codes read this week .
    Last edited by Dave P; 18-07-2021, 10:18 AM.

  • #2
    I hope yours isn't the same as mine - which started off with much the same...
    Initially solved with an oil flush/change & filters but then VANOS failure followed & after oil samples, turns out to be swarf in the oil.

    Mine is worn shells that have worn so much that the crank is scored - wear too much to regrind crank & fit oversized shells, level of swarf then meaning likely damage to other internals, so currently weighing up whether to go for rebuild of existing engine (could be open chequebook) or fit a "known good" used S50 which Munich Legends believe they have located...
    ----------------
    David
    1999 M Coupe (S50)
    >>Read my journal here<<
    2005 Smart Roadster-Coupe Brabus
    2022 Range Rover Evoque PHEV

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    • #3
      Bearings on mine have been replaced so doubt its the engine but could be a sign that the vanos is going bad.(If I had the choice of a rebuilt known damaged engine or good used I would choose the used).

      I believe the secondary air pump can cause problems on start up which can make the engine run lean but not sure of the fix if any.

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      • #4
        Maybe it just needs more than 35 miles a year putting on it mate, no seriously
        Not actually in the least bit fat

        2000 S50 Titanium Silver / Black
        ACS Suspension, Exhaust & Type III Wheels
        Simota carbon air intake | Strong Strut Front Brace

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        • #5
          Originally posted by Fat Tony View Post
          Maybe it just needs more than 35 miles a year putting on it mate, no seriously
          Yes the lack of miles wont help but due to ill health and covid restrictions I havent wanted or been able to get many miles on it. It feels like something has gone bad as the problem appeared overnight rather than gradually getting worse. I have ordered a new icv and some hoses which I will replace as the airbox is currently off being painted so will see if this makes any difference (doubt it will).
          Last edited by Dave P; 19-07-2021, 02:36 PM.

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          • #6
            Originally posted by Dave P View Post
            (If I had the choice of a rebuilt known damaged engine or good used I would choose the used).
            That's an interesting observation and it's the way ML are steering me - yet almost everyone else I know is saying I should stick with my own engine and have it rebuilt.
            Hence the dilemma.... but value your input here Dave.

            The first step is to ensure that the "known good" engine is still available - without that it changes the situation somewhat....

            Fingers' crossed your new ICV & hoses sort your issue & that it's nothing more serious than that.

            ----------------
            David
            1999 M Coupe (S50)
            >>Read my journal here<<
            2005 Smart Roadster-Coupe Brabus
            2022 Range Rover Evoque PHEV

            Comment


            • #7
              Originally posted by Dave P View Post

              Yes the lack of miles wont help but due to ill health and covid restrictions I havent wanted or been able to get many miles on it. It feels like something has gone bad as the problem appeared overnight rather than gradually getting worse. I have ordered a new icv and some hoses which I will replace as the airbox is currently off being painted so will see if this makes any difference (doubt it will).
              So sorry to hear you've not been well mate.
              Not actually in the least bit fat

              2000 S50 Titanium Silver / Black
              ACS Suspension, Exhaust & Type III Wheels
              Simota carbon air intake | Strong Strut Front Brace

              Comment


              • #8
                Originally posted by Dave P View Post
                I have been having some car issues recently which I thought was down to a spark plug problem but a new set hasnt completely cured it , on start up when cold the car runs very lumpy and you can feel the shake through the car but when warm it appears to run ok and smooth, when oil is up to temp the tickover drops to 600 and no shake? . any ideas as although I know it could be one of many things.

                Many parts are new including most hoses and maf . I will try and get the codes read this week .
                When mine did this it was plugs so I suspect yours could be a coil that’s breaking down. To diagnose mine I disconnected each coil in turn to see if the shake got any worse when disconnecting. When it didn’t I’d figured out which one was bad. Does that make sense?

                1998 ///M Coupe

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                • #9
                  Dave, hope you recovered from your health problems. Its bad enough having the Covid restrictions to contend with but having heath issues aswell takes some overcoming.
                  Pete C

                  2000 Z3M Coupe - Cosmos Black Metallic/Black interior. 805 of 821 RHD built

                  Previous BMWs

                  2003 E46 M3 6 speed manual - Carbon Black/Black interior.
                  2000 Z3M Coupe - Cosmos Black Metallic/Black interior. 692 of 821 RHD built
                  1986 M635
                  1985 E28 M5
                  1983 E28 528i Alpina

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                  • #10
                    Originally posted by petecossie View Post
                    Dave, hope you recovered from your health problems. Its bad enough having the Covid restrictions to contend with but having heath issues aswell takes some overcoming.
                    Yes better than I was thanks Pete

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                    • #11
                      Originally posted by Ian_C View Post

                      When mine did this it was plugs so I suspect yours could be a coil that’s breaking down. To diagnose mine I disconnected each coil in turn to see if the shake got any worse when disconnecting. When it didn’t I’d figured out which one was bad. Does that make sense?
                      Yes makes sense, I will check the coils next.

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                      • #12
                        Originally posted by Dave P View Post
                        as the airbox is currently off being painted.
                        #onlydave.

                        Hope you’re ok mate - see you next week with a bit of luck
                        S54 Seca Blue - ACS Short shift and Exhaust. Luverly.

                        Comment


                        • #13
                          Originally posted by Seca Blue View Post

                          #onlydave.

                          Hope you’re ok mate - see you next week with a bit of luck
                          I am much better thanks David

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                          • #14
                            Update, I took the car into Darren Woods who kindly read the faults which gave several for the old idle control valve and for the air intake sensor which I have ordered and due to collect Friday.

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                            • #15
                              New air temperature sensor fitted and hopefully problem cured


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