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S50 ECU Reset: VANOS Adaption Values

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  • S50 ECU Reset: VANOS Adaption Values

    Hello all,

    I heard a few comments today regarding the S50 ECU re. VANOS control.

    It was suggested that the S50 ECU 'learns' VANOS cam position adaptive values (i.e. classic closed loop control), and that the learning process is affected by driving style etc etc.

    The purpose of these adaptive values is to correct the steady-state error between the ECU-requested cam position and the actual physical cam position. Fine in theory, but what if the feedback loop or cam position sensors are malfunctioning or corrupt or just plain wanky (tech term) ?

    Anyhow, apparently a simple ECU reset will clear the adapted VANOS position values. For some E36 M3/ZM owners an ECU reset has improved the perceived performance of their S50-powered cars.

    The question is: how do you reset the S50 ECU (I assume it's an EPROM) ??

    Cheers, Will

  • #2
    Will,

    I think you just disconnect the battery and leave it disconnected for about 30 secs. You lose all the fault codes if you do this, so the ECU must return to default settings, in much the same way that an iPaq PDA needs a permanent charge otherwise you lose all the stored data and have to reinstall any aftermarket installed applications.
    Last edited by exdos; 05-12-2007, 10:45 PM.
    /// Exdos ///
    "Men who try the impossible and fail spectacularly are infinitely superior to those who reach for nothing and succeed" --Napoleon Bonapart

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    • #3
      Nice one Exdos -- i'll give it a try this weekend :-)

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      • #4
        Will,

        Make sure you have your radio code handy though before you do this.
        /// Exdos ///
        "Men who try the impossible and fail spectacularly are infinitely superior to those who reach for nothing and succeed" --Napoleon Bonapart

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        • #5
          Originally posted by exdos View Post
          Will,

          I think you just disconnect the battery and leave it disconnected for about 30 secs. You lose all the fault codes if you do this, so the ECU must return to default settings, in much the same way that an iPaq PDA needs a permanent charge otherwise you lose all the stored data and have to reinstall any aftermarket installed applications.
          Exdos I am not so sure if this provides a permanent solution as the fault codes are there for a reason. Eg if you have an O2 fault and you disconnect the battery for 30 secs yes it will reset itself but only to reappear on driving the car.

          Greenbat

          Ex MC Owner

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          • #6
            Greenbat, I maybe wrong but i dont think that is what exdos is getting at. I think he was just using the fault code memory as an example about the ECU losing its "driving style memories" and other info when the battery is connected. I dont think he was suggesting that its the solution to engine faults rather just losing the memory of conservative driving which may or may not??? affect the performance due to the ECU changing its perameters to suit this kind of driving.

            Obviously if the engine/sensor faults are there they will re-surface again as soon as the car has been driven again.

            please correct me if i am wrong ;)

            regards

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

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            • #7
              Originally posted by Greenbat View Post
              Exdos I am not so sure if this provides a permanent solution as the fault codes are there for a reason. Eg if you have an O2 fault and you disconnect the battery for 30 secs yes it will reset itself but only to reappear on driving the car.

              Greenbat
              Greenbat,

              It is suggested that all fault codes are read before you ever disconnect the battery otherwise they will be lost from the ECU's volatile memory (??). Obviously, if there is a hardware fault such as a defective 02 sensor then this will create another fault code when you reconnect the battery, but some of the other faults, such as number of misfires that might have been previously recorded would be permanently lost. Likewise, all previous ECU adaptation to driving style and fuel type etc will be lost though.
              /// Exdos ///
              "Men who try the impossible and fail spectacularly are infinitely superior to those who reach for nothing and succeed" --Napoleon Bonapart

              Comment


              • #8
                I don't know if this will work on your cars, but it certainly works on my Z4 and my 330i. On the 330i in particular this makes a huge difference.

                Throttle adaption reset

                Turn ignition off
                Turn key to "on" position
                Wait 15 seconds
                Turn ignition off
                Wait another 15 seconds

                Start the car.... you should find the responsiveness has been reset.

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                • #9
                  I'm not 100% sure that disconnecting the battery will reset the adaptation values. A good diagnostics tool will have the function to do this. If you ever come past Luton pop in and I'll do it for you.

                  From my understanding it is not only the Vanos that is affected by the adaptation but also ignition timing. Anyone who has done a track day will know the feeling when you drive the car afterwards and it feel like it has some extra go.

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                  • #10
                    thanks for the kind offer Maahny -- i understand that the S50's ECU uses an EPROM (flash memory) chip to retain adaptive values.

                    A OBD scan tool is required to reset the ECU -- i'm gonna try and source one via my local motor factor....

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                    • #11
                      Adaptation is stored in the E2PROM on the ECU, this area is run in RAM whilst ECU is operational. If you power down the ECU on powering it back up up it rewrites the E2PROM from the EPROM to a base setting. This clears adaptation. On first switching the ignition on throttle base settings are relearnt also.

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