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  1. #1

    Join Date
    Feb 2008
    No. MN

    MSX 150 Throttle Body Sweep

    So if I am reading right, everytime you wake the EMM up, the throttle body should sweep open aand closed?

    If the throttle body does not sweep open/closed, then what would be the diagnosis as to a fix?

    What does disconnecting the relay with engine running do?

  2. #2
    desperado's Avatar
    Join Date
    Aug 2007
    Montreal, Canada
    The ETB will not always sweep. It will perform the sweep routine when the idle speed adaptive values stored in the ECU memory are outside a predefined maximum/minimum ranges. When this happens, the ECU will trigger the sweep routine to rebuild the ETB true position table. Once the ETB position table is updated with new values, the ECU will identify a new set of idle aim values/positions. Next time the engine is started, the ETB will be in this exact position. If the idle is fine at operates within normal parameters..... then the ECU will not trigger the sweep routine anymore. There are other reasons why the sweep routine is triggered aside from the above example -- new ETB is installed (the ECU will know), ECU is reset, ECU reflash, ETB electrical connection issues, lambda values outside normal range..... and many others that I am certainly not aware of....

    So.... bottom line is: if 1-) the engine idles fine, 2-) "ETB learning" value is "True" in Digital Wrench and 3-) engine can reach top rpm above 7,200.... then the ETB is most probably all fine.

  3. #3
    Kosh's Avatar
    Join Date
    Sep 2007
    As usual Desperado you have done an excellent job of explaining in an understandable fashion how things work. I have pasted some information I came across in the pastI hope it helps also.

    Chapter 2
    Programming the motorised throttle housing
    For this system to operate correctly, it must be programmed.
    The programming procedure consists of programming the closed and fully
    open positions of the throttle.
    The throttle position programming procedure should be performed after:
    • replacing the ECU,
    • replacing the motorised throttle housing,
    • repairing the motorised throttle housing after a fault is detected,
    • downloading the ECU,
    • telecoding the ECU.
    Motorised throttle housing programming procedure
    • reconnect the wiring harnesses,
    • switch on the ignition,
    • leave the ignition on for at least 10 seconds (do not switch off the ignition
    during these 10 seconds and do not press the accelerator pedal),
    • switch off the ignition and leave it off for 15 seconds (the ECU records the
    motorised throttle programming parameters in the EEPROM - this is the
    POWER LATCH phase),
    Warning: Do not switch the ignition on during these 15 seconds.
    Important: If the values are not programmed:
    • the system will not control the engine torque correctly as a
    function of throttle opening,
    The ECU will effectively not be able to precisely recognise:
    • the closed and fully open positions of the throttle.
    This operating fault will last until the ignition is switched off and until the
    POWER LATCH sequence has finished (minimum duration = 15 seconds).
    The throttle position is also programmed automatically during the engine's life
    to counteract wear in the throttle's minimum end stop.
    In effect, the ECU systematically compares the memorised "Limphome"
    position (non controlled throttle position) with the position when the ignition is
    switched on.
    If this value is not equal to 300 mV, the ECU will perform the programming
    Therefore from time to time, after the end of the POWER LATCH sequence, a
    clicking noise from the throttle can be heard as it comes into contact with its
    end stops.
    This is not an operating fault.Chapter 2

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