Engine RPMs Up and Down all time

Discussion in 'Crazy-Awesome almost Dakar racers (950/990cc)' started by axelh, Dec 22, 2012.

  1. axelh

    axelh Frog - Riders

    Joined:
    Jan 2, 2007
    Oddometer:
    52
    Location:
    Chile
    My 990 with 20k miles, the engine RPMs when you are not accelerating goes up and donw all time, somtimes stay up for some seceonds and then goes down. I cleaned all injector, injector body, fuel filters, etc... but it still do the same, somes idea what can be the problem ?

    KMT service told me that I have to change all injector body, but this cost a fortune and I dont think this is the problem.

    Thanks for the help !!!!
    #1
  2. Peanuts

    Peanuts Long timer

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    TPS needs setting up.
    #2
  3. skipman

    skipman Been here awhile

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    Oddometer:
    185
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    east tn
    Mine does that sometimes. Seems like riding tight trails at low rpms,brings it on. Not always tho.:huh

    TPS ?
    #3
  4. Peanuts

    Peanuts Long timer

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    #4
  5. Martynho

    Martynho No more Chilegringo.

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    Hi, I am in Santiago also and am having the same problem with my 990R. My buddy Fabian is also having the same problem so I thought it may be you mate.

    If not PM me with your cell and we can talk. Fabian and I have spent looooong hours with Claudio Nilo trying to sort this out and have eliminated some of the variables, looks like you have also so between the 3 of us maybe we can come up with a solution.

    Like you have stripped the bike 4 or 5 times now and have checked all the sensors, wires, balanced the throttle bodies, checked the Throttle Position Sensor setting (it was ok within spec), checked the seating of the injector bodies to make sure there are no air leaks or splits.

    I now have the cable to link a PC to the ECM on the bike, and have the tuneECU software to diagnose and even remap the bike, althugh I am still browsing up and down the "got tunes" thread to figure this out and not make an almighty fucking mess of it

    Having said all this for the last 2 days the bike has miraculously run perfectly. It has done that before however and then just as suddently started idling at anywhere between 2000 and 4000. Interesting when you shut off on your way into a curve fully committed. I have started riding like I did my old 2 stroke air cooled motocrossers....one finger on the clutch at all times :eek1

    Anyone else out there ever had this and know of a solution. Please!?

    Saludos - Martyn

    #5
  6. skipman

    skipman Been here awhile

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    +1 on the finger on the clutch. 2 weeks mine cut out in a curve doing about 40 mph in gravel. body slammed me like a bitch,and it hurt....
    #6
  7. MAXVERT

    MAXVERT OG on da OC

    Joined:
    Jan 19, 2004
    Oddometer:
    1,064
    Location:
    Sun Valley Idaho, Baja Arizona
    My first '07 had a similar issue which made the bike almost unrideable.
    As those above I tuned it with tune ECU,
    I had two 990's at the time one ran fine so I changed ECU's throttle
    bodies, sensors, etc.with no luck.

    Finally I got the bike back to running like it should by making fine adjustments
    to the small screw which adjusts the throttle position on start up.
    That's on the underside of the small electrical/mechanical sensor on the front
    right side of the FI's

    I removed the airbox and reinstalled the injectors and made the adjustments with the bike running.
    Just a small adjustment was enough.
    Hope this helps.

    Martyn, I got the bike from the shipper and am now in Mazatlan after
    riding a 1500 mile loop through Northern Mexico ( Copper Canyon
    Durango, etc )

    We are headed South and with luck hope to see you in Chile.

    Max
    #7
  8. skipman

    skipman Been here awhile

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    east tn
    Max...did your bike do it all the time or just every now and then? Mine does at start up sometimes.not that often, other times after long sections of tight stuff at low rpms...
    #8
  9. Head2Wind

    Head2Wind MotorcycleMayhem

    Joined:
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    check the clutch lever switch to make sure it working correctly...
    #9
  10. Martynho

    Martynho No more Chilegringo.

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    Hope you were ok Skip and no serious damage to you.

    #10
  11. Martynho

    Martynho No more Chilegringo.

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    Thanks for the tip, will do that. Can I just eliminate the bugger and have done? I dont like what it does anyway

    #11
  12. Martynho

    Martynho No more Chilegringo.

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    Hey Mark,

    Good to hear you guys are back on the road. I salute your stoic spirit in just getting on with the Adventure despite the setback. :clap

    Let me know when you and Bonnie are on approach mate. We`ll get the meat on the fire and ready the pisco sours :freaky

    If we plan it right hopefully Katie and I can ride with you guys for a few days eh?

    Abrazo - Martyn

    #12
  13. Martynho

    Martynho No more Chilegringo.

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    Well at least I think so. Shorted the clutch switch out this afternoon and it rode home perfectly, like it hasnt run since the engine rebuild! Hopefully this is the fix. You have no idea what a relief it is we have been working on this for 2 months now

    Great early Christmas present, thanks ever so much

    What the hell has the clutch safety sensor got to do with fuelling/idling?


    #13
  14. Head2Wind

    Head2Wind MotorcycleMayhem

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    The switch tells the ECU (among other systems) that the clutch is disengaged (if lever is pulled in) and therefore should not cut fuel on closed throttle if I recall correctly...

    I'd have to look at the wiring diagram to see if the switch is supposed to be closed or open when the lever is pulled in.

    If the mod you made effectively is telling the ECU the clutch is disengaged all the time, this may have other undesirable side effects
    #14
  15. Martynho

    Martynho No more Chilegringo.

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    Wont be able to get to the wiring diagram until later this week.

    I can start the bike in gear so it seems it thinks it is disengaged all the time. What undesirable side effects would you anticipate?

    #15
  16. Head2Wind

    Head2Wind MotorcycleMayhem

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    If I recall correctly, other people have reported that it makes the bike run like crap in other RPM ranges beyond the idle-mid range... I have no direct experience with the 990 with a disabled clutch switch so I do not know for sure.... my soon to be running EFI 950 will allow me to directly experience/experiment
    #16
  17. Martynho

    Martynho No more Chilegringo.

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    Well I ran it to the redline on the highway on the way home this afternoon, seemed smooth right the way up. Will keep you posted how it goes over the next few days.

    Thanks again for your input

    #17
  18. Martynho

    Martynho No more Chilegringo.

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    It ran fine for a day then started playing up worse than ever. Unstable idle anywhere from normal for a few hours, then 2000 and occasionally up to 5000 rpm.

    Another inmate has suggested I may have a dicky TPS unit. I have checked the values with tuneECU and it is within range, but I have noticed that at idle (when it is behaving normally, which is usually does on the the stand, only goes AWOL on the move) the 0% opening value fluctuates between 0.64v and 0.65v...maybe it is sending out an intermittent signal and screwing up the ECU?

    I have located the spare TPS units in the USA as they are not available here in Chile. Hope I can get them here and fitted before I leave for the Dakar on the 14th.


    #18
  19. StevenD

    StevenD Hmmmm, dirt!

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    with the switch shorted you'll be in clutch map, no good for power etc. only way to remove it is to leave it open and disable some other switches and stuff meaning you can start the bike alway's (also when in gear, no clutch).

    tps is tricky, but a diffrence of 0.01 volt is very normal at 0 throtle. all but some multimeters have bigger margins than that.
    Make sure the reading is OK on full throtle.
    #19
  20. Martynho

    Martynho No more Chilegringo.

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    When it is behaving it runs fine through the rev range, apart from the usual glitchyness typical of a 2007 map.

    I will order a new clutch switch and reinstall to eliminate this potential variable.

    Still unhappy about all this. Frustrating the hell out of me and my KTM shop

    #20