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S54 throttle response and hesitation when cold

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  • #16
    Hi Simon, one thing you can try is resetting the vanos.

    After a couple of weeks of 'fuel economy mode' driving to work my engine can sometimes be a bit hesitant at the low revs. This is apparently because the ecu 'learns' your driving stlye and adapts to it.

    If you have been driving sedatly for a bit try resetting the vanos by doing the following:

    with engine off, turn key to 2nd click (1 before ignition) and stay there for 10+ seconds, then turn key back to off position and wait another 10+ seconds. Then start the engine, usually the idle revs start a bit higher 1500 or so and slowly come down over 5s or so. I have found after doing this it adds a bit of punch to the engine.

    There is a thread about it on here somewhere i think.
    Imola S50 1999

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    • #17
      Originally posted by cragg711220 View Post
      Hi Simon, one thing you can try is resetting the vanos.

      After a couple of weeks of 'fuel economy mode' driving to work my engine can sometimes be a bit hesitant at the low revs. This is apparently because the ecu 'learns' your driving stlye and adapts to it.

      If you have been driving sedatly for a bit try resetting the vanos by doing the following:

      with engine off, turn key to 2nd click (1 before ignition) and stay there for 10+ seconds, then turn key back to off position and wait another 10+ seconds. Then start the engine, usually the idle revs start a bit higher 1500 or so and slowly come down over 5s or so. I have found after doing this it adds a bit of punch to the engine.

      There is a thread about it on here somewhere i think.
      Is this process the same for both S50 and S54?

      Jez
      1998 Cosmos Black - Not quite standard ...

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      • #18
        Good point Jez, I'm not sure. I should point out I have an S50.
        Imola S50 1999

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        • #19
          This could be what your looking for...

          http://www.z3mcoupe.com/forum/showth...esetting+vanos

          also found this

          http://www.bimmerfest.com/forums/sho...d.php?t=266162

          hope it helps....let us know..

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          • #20
            My car has a v similar fault/stutter.
            Left it at my indy last night so that could run the car from cold while plugged into the diagnostics.
            It turns out i have a dodgy exhaust gas temp sensor, and this may cause the trouble.
            Once its replaced i'll post any significant results.
            The M Coupe ... For those who understand, no explanation is needed. For those who do not understand, no explanation is possible.

            Now ... S54: Sapphire Black/Black-Black/HK+6/Cruise/Sun Roof/H~Lamp wash///ACS Road Suspension/Rogue Engineering rear top mounts/Braided clutch hose
            RIP ... S50: Artic Silver/Black-Grey/HK+6/Cruise/Side 'bags/Grad Tint///ACS Short Shift/Strong Strut/K&N/HIDs & Angels

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            • #21
              Cheers for the replies.

              I have now replaced my Throttle Switch and this seems to have fixed the problem. It is now much smoother when up to temperature - still a little hesitant when cold though but it sounds like this is a characteristic.

              Thanks

              Simon

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              • #22
                What sort of cost??
                might replace mine to try an iron out the lumps in the throttle response ...

                The M Coupe ... For those who understand, no explanation is needed. For those who do not understand, no explanation is possible.

                Now ... S54: Sapphire Black/Black-Black/HK+6/Cruise/Sun Roof/H~Lamp wash///ACS Road Suspension/Rogue Engineering rear top mounts/Braided clutch hose
                RIP ... S50: Artic Silver/Black-Grey/HK+6/Cruise/Side 'bags/Grad Tint///ACS Short Shift/Strong Strut/K&N/HIDs & Angels

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                • #23
                  Trundler. See my earlier post for cost.
                  S54 Titan Silver metallic. Black leather, most factory options including sunroof, Becker Cascade and Becker Silverstone changer.

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                  • #24
                    perfect - for £35 might as well chuck on a new one!!
                    Cheers.
                    The M Coupe ... For those who understand, no explanation is needed. For those who do not understand, no explanation is possible.

                    Now ... S54: Sapphire Black/Black-Black/HK+6/Cruise/Sun Roof/H~Lamp wash///ACS Road Suspension/Rogue Engineering rear top mounts/Braided clutch hose
                    RIP ... S50: Artic Silver/Black-Grey/HK+6/Cruise/Side 'bags/Grad Tint///ACS Short Shift/Strong Strut/K&N/HIDs & Angels

                    Comment


                    • #25
                      I think it was closer to £50 but certainly worth it.

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                      • #26
                        'Evening Gents, I have some engine hesitation, juddering problems also and deturmined to get to the bottom of it.

                        Symptoms:
                        It's between 1000 - 2000rpm low throttle / partial throttle under gentle acceleration.
                        Slightly worse when cold.
                        Feels like misfire, not sure if it is, my plugs looks good.
                        Even at 60-70mph constant throttle it's can hesitate as if it's out of fuel.
                        Idle may be slightly rough.
                        Idle speed when hot is fine, smooth, consistant. But when cold it sometimes rises to 1500 then dips to 700-800.

                        The problem was massively reduced when I replaced the vanos solenoid o-rings on bith intake and exhaust sides a couple of weeks ago. (easy to do I recommend other people with hesitation problems do this)

                        Resetng the adaptions doesn't help.

                        Thought I may have a problem with an air leak from the brake servo, but checked it today and it's not that.

                        Cleaned the MAF. Spark plugs are new(3k miles) Replaced the inlet trumpet o-rings. New air filter. Throttle cable is fine.

                        I can drive the car smoothly but it's just being a bit of a b*tch at the mo and getting anoying.

                        My plan now is to clean out the idle control valve tommorow and take a good look at the vacum hoses while I'm there.

                        Then:
                        Coils
                        Throttle Position Sensor/Potentiometer
                        MAF sensor (replace or try a known working one)
                        Fuel filter & Pump
                        Cam position sensors
                        Lambda sensors

                        Sorry for the epic post!


                        Craig
                        Imola S50 1999

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                        • #27
                          i would be really interested to know what you do that works, as mine is a complete fucker at the moment, and ive replaced the MAF already.

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                          • #28
                            Cleaned out the idle control valve today. Didn't make any difference it was quite clean already, only a small amount of black stuff came out.

                            I tried moving the throttle cable adjuster to put the trottle cable slightly in tension so any play in the throttle linkages are taken out at idle. To early to say if it's made any diference (I doubt it will).

                            Got some injector cleaner today while in halfrauds. I used some a few weeks ago so again I doubt it will make much difference, we'll see.

                            Next on the menu is either coils or MAF whatever I can get my hands on first. I had a diagnostics done at Bexly Motor Works a few weeks ago and neither shows up.


                            The one fault that was brought up was secondary air pump. From what I've read it's to do with emmisions control and Nigel at Bexlys said it was common and wasn't anything to wory about. Now I'm wondering if it's a problem, anyone have any ideas what it is?
                            Imola S50 1999

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                            • #29
                              Sorry to resuscitate this old thread but I'm beginning to think the problem I thought I'd had solved earlier is potentially answered by these postings and ties into the throttle actuator error codes the car recorded a month or so ago(lumpy hesitant at lower revs - it seems to have crept back in with the cold weather.)

                              I've checked through a number of other sites where mention is made of a similar problem for S54 engined cars being solved with the replacement of the same 'throttle switch' that I guess Ian or SimonClark have mentioned here.

                              Can someone with a better technical understanding than me explain if the earlier part of this thread is referring to changing only part # 13637840383 (which seems to be called Throttle position switch or throttle valve switch depending on which source you look at) which sits at the front end of the throttle housings but not replacing the matching switch part what looks to be exactly the same part attached to the throttle actuator?

                              By way of explanation
                              http://bmwfans.info/parts/catalog/Z3..._acceleration/

                              Throttle valve switch part #13 63 1 402 143 discontinued but listed now with replacement part # 13 63 7 840 383

                              http://bmwfans.info/parts/catalog/Z3...ttle_actuator/

                              Throttle valve switch part #13 63 1 402 143 discontinued - no listed replacement.

                              Guess this is why Munich Motors were explaining I could get a replacement switch for one of the two but would have to buy the whole actuator unit for the other where the switch was probably the component at fault.... which leaves me a little confused as the old switch versions were seemingly identical. Does the new part number not fit both elements like the old?

                              Can anyone point me in the direction of an explanation as to how these parts work and why replacing only the £30 switch not connected to the actuator would solve the problem of throttle control - I'm assuming they do different jobs? The actuator costs three figures..

                              Cheers

                              PS Finally got my Bentley Service manual today from Amazon.co.uk - looks like it will be interesting reading and was cheaper than some of the recent sales of the same on ebay or from the US that I'd been considering.
                              ex- 2000 Titanium Silver S50 with AC Schnitzer road suspension, exhaust, rear wing and gear knob
                              now 2002 Sapphire Black S54 with black/red interior, S54 Bearing Shell upgrade with ARP Con Rod bolts, Cam shaft bolt upgrade

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                              • #30
                                'Yadi,

                                did you ever get round to resolving this issue?
                                Did you replace 1 or both switches?
                                I have been a touch lazy, but need to get this sorted as the hestitation is getting annoying, and is per the other descriptions in this thread.

                                Cheers!
                                The M Coupe ... For those who understand, no explanation is needed. For those who do not understand, no explanation is possible.

                                Now ... S54: Sapphire Black/Black-Black/HK+6/Cruise/Sun Roof/H~Lamp wash///ACS Road Suspension/Rogue Engineering rear top mounts/Braided clutch hose
                                RIP ... S50: Artic Silver/Black-Grey/HK+6/Cruise/Side 'bags/Grad Tint///ACS Short Shift/Strong Strut/K&N/HIDs & Angels

                                Comment

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