990 Adventure strange idle speed issue

Discussion in 'Dakar champion (950/990)' started by Erwin P, Sep 11, 2019.

  1. Erwin P

    Erwin P Adventurer

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    Fellow inmates,

    My KTM 990 Adventure 2007 (EU) has developed a rather strange issue.
    When i put it in any gear, clutch engaged or free doesn't matter, it runs at 3500 rpm.

    When i put it in Neutral it directly goes to 2800 rpm, and after like 20 seconds goes slowly down to its normal idle speed.

    If i put it in any gear again it goes directly back to 3500 rpm.

    Does anybody recognise this problem, or even better, has a solution?

    Thank you guys in advance!
    #1
  2. speedy 1

    speedy 1 Wizard

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    replace the throttle position sensor
    part #61041077000
    look in the "how" section on this site for guidance
    #2
  3. DirtyADV

    DirtyADV Long timer

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    Or it could end up being the idle stepper.

    Interesting to get around with idle stuck close to 6000 rpm.

    /Johan
    #3
  4. Erwin P

    Erwin P Adventurer

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    Thanks guys!

    I replaced the TPS some time ago for another problem. It is now reading nice values.

    Mmm the idle stepper deserves a look i guess. Any way i can find out its broken? I have TuneEcu
    #4
  5. Erwin P

    Erwin P Adventurer

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    Oke i've gone a little further in my research, but still the same problem.

    - I started with al the checks as listed in de LC8 workshop manual. In cold engine, not running, everything OKE.
    - TPS a bit low, but when the problem started it was a bit high, so i corrected it to this sowewhat low value, but no difference.
    - After that i started and finished the 15 min reset. It didn't do anything, but i saw some troubling numbers wich i have a few questions about (see picture below, taken during 15 min reset).
    1: Wich O2 sensor is front and wich is rear? The left one is being way to high. I suspect the front one since that one is white (taken it out resently), the rear i don't know since that was harder so i didn't bother at that time.
    2: Wich manifold is front and rear? The one giving 2,15 (right) was going up and down between 2,10 and 3,4. That would mean a leakage i guess...?
    - The 2 questions above would both indicate air being taken in (through a intake rubber or something like that). But since the one is on the left and the other on the right on TuneEcu puts a question mark...
    - After the 15 min reset i've tried playing with the throttle. In Neutral is was slow to fall down from 2500 to about 1700 (same as in the picture, but idle should be 1450...). In any other gear it would go up to 3000/3500. Wich would be strange for an air leakage...
    - Now i disabled the ''idle speed control''. No difference only a bit harder to start the engine, after that same same. So i can cross the idle stepper of the suspects list.
    - Typing this something jumps to mind. Do the O2 sensors do anything in Neutral? If not, do they at any given gear with throttle closed?
    EDIT: I just disabled the O2 sensors. After starting it runs high for about 5 to 20 seconds. After that its nice and idle. On the centerstand in first gear it runs at about idle to 100 rpm higher (explainable sinds is does drag the rear wheel).

    So now i fixed my symtomes but i still have a defect.

    Anyone who could answer any of these questons?
    (@Zuber hoping you are reading this :*sip*)

    cf933e07-c7aa-45ce-8f6a-e2e66f07e6e0.jpg
    #5
  6. speedy 1

    speedy 1 Wizard

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    Whenever my 07 runs oddly replacing the TPS fixes it.
    It has behaved in exactly the same way as you have described.
    TPS on these bikes are an old fashioned potentiometer. A contact voltage divider style meaning it is a carbon brush that moves on copper wire.
    All other types of TPS for engine electronic controls are contact less. They are hall effect sensors, inductive sensors, or magnetoresistive. Always a sealed unit.
    For the KTM there is no seal on the throttle shaft nor is the sensor sealed. The fuel fumes migrate to and contaminate the sensor.

    as always ...
    your results may vary
    #6
  7. Erwin P

    Erwin P Adventurer

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    Yeah, but the sensor is not even 6 months old and, as i told above, it runs OK with the O2 sensors disabled.
    #7
  8. Erwin P

    Erwin P Adventurer

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    I found out the left O2 sensor (2,243V) is the REAR one. As is the cilinder with the highest pressure.
    - I tried to synchronise the two, but at full range of the adjuster screw there stays a difference of 130 mBar.
    - Now after a few more tries it repeats its problem, even with the O2 sensors disabled. I still think the rear O2 sensor is faulty, but not the source of the problem i have now.

    Now i guess i have to wait for the intake rubbers i ordered.
    #8
  9. Erwin P

    Erwin P Adventurer

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    Just to check myself (and your thoughts about is).
    If an air intake manifold is leaking, waht colour would the spark plug and the O2 sensor get...?
    #9
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  10. Koen

    Koen Adventurer

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    It will run lean, so white. What you can do is spraying with some brake cleaner around the intake manifold. If it sucks in the brake cleaner you will hear the enginer rev up.
    #10
  11. Erwin P

    Erwin P Adventurer

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    Well that present a bit of a problem... They're black...

    I think they will react to it no matter what because they are so close to the open intake don't you think?
    #11
  12. Koen

    Koen Adventurer

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    no, air intake sits higher, just spray underneath the airbox if possible.

    if you look here: http://www.ktm950.info/how/Farkels/adventure/air_filter/sportingwood_AF_conversion.html

    Then where he says: Next you can reinstall the throttle body boots, tightening the bottom clamps.

    This is where you want to spay, because this is after your throttlehousings. If it sucks in air here, it will cause higher rpms. All the air being sucked in via the throttlehousings (so vie your airfilterbox) is measured so the ecu will try and take care of that.
    #12
  13. Erwin P

    Erwin P Adventurer

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    Mmm the airbox only measures air temperature and manifold pressure, not air mass if i'm correct...

    I know what the underside looks like, have dismounted it a few times for valve checking. You first put on the air box, after that you put on the intake rubbers, into those you put the throttle bodys. Spraying around there would also go into the throttle body's i guess?

    I just came up with another idea. Maybe the valves on the rear cylinder don't close correctly. I'm gonna check that tomorrow.
    #13
  14. Koen

    Koen Adventurer

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    the cylinder valves? like inlet and outlet valve?
    #14
  15. Erwin P

    Erwin P Adventurer

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    Yes those.

    De in en uitlaatkleppen zoals wij zouden zeggen ;)
    #15
  16. 99spike

    99spike n99b

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    Double check map sensor hose for leak and or swap ambient press sensor for one map sensor all 3 are same part
    #16
  17. 99spike

    99spike n99b

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    Check idle stepper shaft rotates freely
    #17
  18. Erwin P

    Erwin P Adventurer

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    Mmm i'll add the MAP sensor check to the list.

    It's not the idle stepper. With idle disabled it stil does the same.
    #18
  19. kevinA

    kevinA Been here awhile

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    Check for intake tract leaks. Also the brass nipples on the sides of the throttle bodies. Beat her hose from engine to intake. Velocity stacks are on n tight. Clamps n seals tight from head to throttle bodies. No other holes, leaks or airflow disruptions anywhere etc. cause the fuel to not fully mix with air and lean condition.
    #19
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  20. mountaincadre

    mountaincadre Long timer

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    Can you but something on the brass nipples? PTFE tape or something like that.
    #20