990 Adventure strange idle speed issue

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

  1. kevinA

    kevinA Been here awhile

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    One side on each head goes to a sensor the other I forgot I think the evaporative canister. Take the one side to the emissions out and put in a small bolt medium lock tite in its place.

    Forgot the size but keep it small in length to avoid having it stick out into the intake and disrupting airflow. Or just glue gun the hole in the nipple but it might make someone later think some hose is missing. It’s not very technically advanced. I think it’s just ment to suck fuel fumes from the evaporative canister back into the engine.

    Don’t as some people have run a hose connecting the two heads.
    #21
  2. Zuber

    Zuber Zoob Supporter

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    Basics - it is getting more air than normal.
    1. vacuum leaks are by-passing throttle plates, broken intake boots, throttle bodies not seated
    2. throttle plate is open, TPS voltage is off, idle stepper motor or wiring is bad (more rare), cables hanging or other mechanical problems,
    #22
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  3. speedy 1

    speedy 1 Wizard

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    Ignition box is a precision electronic device that works best when provided with a precision sensor signal.
    A potentiometer is an antiquated electronic device developed it the days of tube radios and TV's.
    The KTM version is tiny, 1/4 turn and not sealed. Very hard for a potentiometer to be precision with these 3 factors.
    To keep my bikes in good running condition I stock many consumable items. Tires, brakes, chains, filters, oil etc.
    In this garage the KTM version of a TPS is a consumable.
    Try a new one ... if it's not the fix then the worst case scenario is there's an extra on the shelf.

    A vacuum leak rarely acts erratic and can often be heard, especially can be heard if it is so large that the engine runs up to high RPM.

    as always ...
    your results may vary
    #23
  4. NKL

    NKL Been here awhile

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    72,000 miles and still on the original TPS, what do you do to yours to need to replace them so regularly.
    #24
  5. NKL

    NKL Been here awhile

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    If you can't get the throttle bodies balanced it may be the drilling in the head blocked, a break in the hose for the MAP sensor or you have valve clearances well out on one head.

    Or there is an air leak in the manifold or rubbers
    #25
  6. Erwin P

    Erwin P Adventurer

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    But why the difference between idle in gear gear and neutral?
    Does it use a different map in neutral?
    #26
  7. Salzig

    Salzig Long timer

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    My '07 990 does the same when the TPS is not spot on.
    Not to your extent, but I had it hold 2000-2500 rpm in gear that dropped to a normal 1400-1500 rpm if I put it in neutral.
    It only acted like this when engine was cold though.
    #27
  8. Zuber

    Zuber Zoob Supporter

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    This took some thought. Putting it in gear puts a slight load on it, so the auto-idle has to crack the throttle open a little. Then it goes out of control. Maybe...
    #28
  9. Erwin P

    Erwin P Adventurer

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    But with idle control of it keeps doeing the exact same, only a bit hard to start.
    In gear rolling clutch in slowing down from high to low speed it does the same. However much the clutch is dragging, in you theory it would go lower in revs, but it stays the same problem.

    Is there any difference in Ignition, mapping, fuelling, O2, etc etc between Neutral and gear?
    #29
  10. Zuber

    Zuber Zoob Supporter

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    If the 990's run a different map in neutral, it's not shown by TuneECU. I always assumed that it does not.

    I know the 690's do have a Neutral/clutch-in map.
    #30
  11. Erwin P

    Erwin P Adventurer

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    First of all, thank all you guys for the help so far.

    Oke still a few more days before i'll have the parts and time to attack the possible inleak(is that a word in English?) problems.

    But what did came in today is my compression meter.
    But how high should the pressure in the rear cylinder be? Didn't have the possibility to check the front yet since the air filter box and tanks are still on.

    It showd 8,5 bar (120PSI), but starts at 0 so that means 9,5 (140 PSI) bar absolute.
    #31
  12. Koen

    Koen Adventurer

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    Measuring 1 cylinder doesn't tell you so much. you need to do both. They both wear at the same rate, so if they both have the same value than its fine. Ofc when it gets really low or really different (they say within 15% is fine), say you have 9 and 6, than you have to see if it is a valve or a ring problem and then go from there.

    As a site note, it also differs a little how you measure, warm or cold engine. Should be warm (not hot either) and also keep in mind that these measurement tools are not super accurate either.
    #32
  13. Zuber

    Zuber Zoob Supporter

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    120 psi is good, though a better test is the 'leak down' test.
    #33
  14. Erwin P

    Erwin P Adventurer

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    Oke problem is solved!

    Spoiler:
    The rear hose to the MAP sensor was leaking in.

    But here is al little more why that was the problem and how it was possible the spark plug and O2 sensor went black instead of white.
    - The leak wasn't pulling enough air in to make the engine run any different. Spraying brake cleaner all around every rubber etc didn't have any effect. It was barely sucking any air in. But being right next to the MAP sensor it raised the pressure it measured.
    - Below a given RPM and Throttle postion the ECU uses the L-maps (injection by air pressure measured by the MAP sensors), above that it looks at the F-maps (RPM and Throttle position). The L-maps are leaner to presserve fuel. At higher pressure it injects more fuel, explaining why the spark plug and O2 sensor went black.
    - So i changed the Throttle-position values to 0 in the F-L switching map (then it always looks at the F-map). That fixed the symtomes. Now i was convinced the valves and piston rings didn't need checking.
    - After this i took a closer look at the hose between the MAP sensor and intake manifold, it was having a tiny little crack only visible when twisting it.
    - After fixing this and, putting the maps back to standard and synchronising the Throttle bodys (wich was now about 10 seconds work) it has been running perfectly ever since (about 120 km).
    #34
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  15. mountaincadre

    mountaincadre Long timer

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    Good man.
    #35
  16. Erwin P

    Erwin P Adventurer

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    Still trying to figure out why it made a difference between idle and gear. Does the L-map only work in gear?
    #36
  17. Koen

    Koen Adventurer

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    nice one!
    #37