KTM 990 Idle Speed Control Stepper Motor Operation

Discussion in 'Dakar champion (950/990)' started by BillyD, Jul 6, 2010.

  1. chevtech

    chevtech Long timer

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    So in other words, against the idle stop, right?!? That makes much more sense! Now we just need the spec for setting the idle stop and we are set!


    :beer
  2. Stmad

    Stmad Adventurer

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    I assume that when you do the "Adjust throttle cable" test in the tuneecu the valve stops at the idle stop ... so yes this is it ...
    There is no point to mess with the idle stop .This is set from the factory.
    Just adjust the tps volts at this position.
    If for some reason you have to set the idle stop then both plates clearance at idle stop should be .0015''
    (this is from my throtle body 2008 990 Andvenrure S Europe).
  3. chevtech

    chevtech Long timer

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    Everything is "set from the factory" at assembly. Doesn't mean it was right when it left, doesn't mean it hasn't changed for some reason in the time you have owned it. Most carbed bikes require minor idle adjustments. Don't think that just because it is a throttle body, it is any different, and can't drift/change over time. It is no different from a carburetor in that regard.Thanks for the specs!

    :beer

    That butterfly spec however...is a hard one to measure/set.

    :(


    Todd
  4. Salzig

    Salzig Long timer

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    @Stmad which manual (year) your're referring to?
    Mine is for models up to 2007 and doesn't say anything for TPS adjusting on EFI bikes, just carburated ones.
  5. Stmad

    Stmad Adventurer

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    I don't know exactly the year it's from my mechanic , he was a ktm dealer (not now) and he show me the page.
    There is a lc8 service manual free somewhere online but this is for 950 not 990.
  6. speedy 1

    speedy 1 Wizard

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    Thanks you for this measurement.
    If you don't mind ... how did you measure this ?
    Down the throat I presume ?
    If it's a feeler gauge then how wide (not thickness) was the gauge ?
    Width of gauge would alter the reading.
    And a further thought ... most production bolts are made with a rolling machine which creates a cup shape on the end of the bolt. The cup will wear down over time and change the throttle opening size. ... Is there any marking on the arm from the bolt or has the bolt changed shape in any visible way ?

    Thanks again kind sir.
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  7. chevtech

    chevtech Long timer

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    I was thinking of using a feeler gauge as well. It will bend against the throttle body throat and shouldn't be too hard to set once I thought about it!


    :beer
  8. chevtech

    chevtech Long timer

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    I'd like to also point out, that butterflies and their corresponding linkages/pivots wear in/out and the butterflies likely close down over time!

    Good spec to check!


    :beer
  9. Stmad

    Stmad Adventurer

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    @Salzig This is from your repair manual it is in section 7-51.
    THAD Throttle valve sensor voltage Min limit 0.3 Max Limit 4.5 volts Completely closed 0.56-0.64 V
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  10. chevtech

    chevtech Long timer

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    You are making a good entry as a noob dude!

    :thumb

    :super

    :queenie

    Cheers!

    Todd
  11. Stmad

    Stmad Adventurer

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    Thanks man !! :super:super
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  12. Salzig

    Salzig Long timer

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    Thank you!
    I never paid attention to that section, my bad.
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  13. Stmad

    Stmad Adventurer

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    My mechanic did the measurements i don't know how he did it but i will ask him ...
  14. Stmad

    Stmad Adventurer

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    And this is from the 2003 - 2007 Repair manual section 7-51 LIMIT VALUES 990 ADVENTURE

    THREF Throttle reference value Min Limit 13.8 Max Limit 20 Unit º Normal value: 15º - 17º
  15. WrldRiderWC

    WrldRiderWC Adventurer

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    Steppers are open-loop incremental motors.
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  16. chevtech

    chevtech Long timer

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    Remind me of the electrical dynamics of that circuit would ya? Or, is google my friend? What does it run on in this system, dwell, frequency, square wave Edit: Pulse width modulated, 12V, or 5V?!? Oh boy, those are old terms, in this noggin! ;)

    I always hated trying to diagnose SM. The waveforms were so sporadic/weird on an oscilloscope, because the voltage inputs were so sporadic based on need, and significance of (RPM) change NEEDED (because it may be perfect and not need to change) at any given time. Unlike almost every other sensor/motor on the car which had either constant voltage changes, as in a signal, or simple twelve volt on off circuits found all over a car. You had to force RPM change and then capture it with a trigger, which was a PITA, because you didn't even know what to set your trigger to, in the times before smart automotive labscopes. Then you had no point of reference to compare waveforms to, except an identical car and a utopian thought of reproducing and capturing the exact same idle change (in other words; no fucking way) to know if the waveform was corrupt, because it was so odd. Didn't get to fuck with them as much as i would like, because they came up with noid light testers for them. They work by verifying the ECU signal to an unplugged stepper motor with ECU firing away trying to change an idle it can't adjust, lighting up a few lights in a dummy connector. They are a simple and effective way to diagnose the ECU or bad stepper (assuming it is frozen) on the SM circuit, at about the same time as you could start commanding them with factory scanners, which of course begs the question:

    Can you run a full output test of the SM with Tune ECU? You can watch for glitches as it spins out/in! Bad stepper motors can stall/glitch when they go bad, just like a flat spot on a starter motor, but sometimes bearing/bent shaft related too! You can command them through their range on almost any factory scanner!!!

    Maybe?!?

    You could just watch for smooth operation just like watching a TPS on a graph, because your eyes are quick when watching the real deal! Sometimes they just stall completely!
  17. Erez1984

    Erez1984 Adventurer

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    This info is allso shown in this manual as im sure some of you will benefit from -

    [​IMG]

    https://www.slideshare.net/FredericBlachon1/ktm-lc4lc8-failure-code


    Personally i cant see how the "Device Operation : Fully Closed 0,56V – 0,64V" help us understand its exact preffered place to be. As far as i can see they say it can sit between 0.56 to 0.64 when closed but there are 8 different options between those 2 values or im missing something here.
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  18. speedy 1

    speedy 1 Wizard

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    The controller does have "fuzzy logic" so it does learn and compensate for where the TPS is set.
    Refer to the "15 minute idle reset" in the manual.
    The controller is always "relearning" so the 15 minute reset isn't required but the learning may take a few rides before the erratic behavior finally settles down.
    My "shade tree" method for setting a new TPS is to have the engine idling so the butterfly is held tight by manifold vacuum.
    The TPS is a resistance measuring device. Temperature rise in all things electrical creates more resistance. So a little heat in the TPS is a good thing as this will provide a more accurate running condition.
    Voltage tends to creep up over time so I set low. .59v is my target.
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  19. chevtech

    chevtech Long timer

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    It doesn't have to be perfect. The ECU has to learn where your idle is regardless, and will adapt a baseline anywhere within those voltage ranges. It probably has a voltage range well outside what is listed here, .56 - .64V is the "safe range". Just pick the middle .60V and then you leave as much adaption to each side as is possible. These voltage ranges are somewhat useless without setting the base idle however. That HAS to be done first.

    :beer

    Todd
  20. Salzig

    Salzig Long timer

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    Just to be rigorous, TPS is variable resistor. It's fed with 5V and it gives back a voltage that depends on its position. If it's set in the exact middle position, the output voltage is always 2.5V, warm or cold doesn't matter.
    IHMO the reason to make adjustments with the engine warmed up is to have all the parts at working temperature and thus at working dimensions.
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