TPS... TPS... TPS...

Discussion in 'KTM 950/990' started by Sumi, Jun 5, 2018.

  1. Sumi

    Sumi Long timer

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    Okay, one more question before leaving to shutter island & burning down the whole bike & house:

    If I install a new TPS, and hook up the bike to Tune ECU (thanks to my friend who re-lended his cable to me) so I can have a voltage reading of the TPS, do I:

    - Retract the throttle cable / idle stepper (a.k.a Adjust throttle cable*)
    - Leave the slack in the cable (so normal startup)

    When adjusting the TPS to 0.6V?

    It's because if I adjust it to 0.6V with the cable pinging I get 0.83V after power-cycling the bike.
    And if I adjust it to 0.6V with slack in the cable, the voltage drops to 0.4V before settling at 0.6V, when the bike is turned on and goes through it's initial startup process.

    *From TuneECU site: KTM only Adjusting the throttle cable :
    The idle speed control stepper motor will be completely retracted and the throttle valves completely closed.
    Switch the ignition switch off, WITHOUT exiting or disconnecting the software, and adjust the throttle cable
    clearance.

    Also: If one decided to drill a hole on the airbox, how does he know where to exactly drill it to end up spot on with the TPS screw? I assume they're not drilling it from the inside out while the TB's are attached?

    Cheers
    #1
  2. 2 SPOT

    2 SPOT bring the rape whistle

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    the throttle adjust box needs to be ticked for the adjustment,,, you dont mention if you have it ticked.
    #2
  3. Sumi

    Sumi Long timer

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    For the TPS adjustment?
    #3
  4. MattF44

    MattF44 Been here awhile Supporter

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    Any chance you’d be willing to document the procedure? Seems like one we’ll all be doing sooner or later and I don’t think I’ve seen it laid out comprehensible and with TuneECU on here / or the HOW (although I could easily be wrong).
    #4
  5. 2 SPOT

    2 SPOT bring the rape whistle

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    No, got confused for a moment I guess,,, throttle cable adjust, not tps
    #5
  6. zeegman

    zeegman Been here awhile

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    Hi Sumi,

    this is what I did to adjust the Throttle (others can correct me if I am wrong).

    Do throttle cable adjustment first - do not worry about TPS voltage yet.
    The throttle adjustment must be done to allow a little slack on the cable when your hand is not on the throttle tube.
    Without the slack the stepper motor can not pull the cable all the way to the zero (closed postion) to make the proper measurement of zero position - and then it needs to move to open the throttle just a bit for proper idle.
    Actually you will notice on starting the bike the stepper motor will cycle through fully open to fully closed zero position - then the stepper motor will move back open just a tiny bit to make idle speed setting.
    It is important not to touch the throttle tube while this is happening because the bike is calibrating the throttle positions.

    If there is no cable slack this will result in run away high idle that some people experience.

    First loosen both throttle cables adjusters screws till there is lots of slack in both cables at handlebars.

    Turn the bike on but do not start the motor (make sure handlebars are straight) and connect the tuneecu software.
    When it has finished cycling the stepper motor double click the adjust throttle cable button in the Tuneecu test page.
    The tuneecu will force the stepper motor to fully closed zero position (not idle) so you can adjust the throttle slack properly.


    With right hand roll throttle to fully closed position (you need to do this by hand since the cable is now completely slack).

    With left hand tighten return cable adjuster (front cable) until you can feel it start to pull the on the throttle tube.

    With left hand loosen return cable adjuter screw about 3/4 to 1 turn.

    Let go of right hand on the throttle grip and tighten backup nut on return cable adjuster.

    Now tighten the throttle cable adjuster (rear cable) until there is only 3-5mm of rotational slack movement on throttle tube.
    You can measure this by putting a mark on the throttle cable housing next to the throttle tube grip and another mark 3-5mm away and a mark on inside part of throttle tube grip to align with other marks - can use tape if it helps.

    Tighten rear throttle cable backup adjuster nut.

    You can turn off bike or now is a good time to adjust TPS voltage since stepper motor is fully set to zero position.

    At this point I would adjust TPS to set voltage to 0.6V.
    You adjust TPS by loosening TPS screw (Torx - I forget which size) and moving body of TPS rotating it one way or another to set proper voltage - it is kind of touchy I find so need to move it in very small amounts.

    Do not touch the throttle grip with your hand while this is happening.

    The adjustment TPS screw will be on front right side (right when you are sitting on bike) of the throttle bodies of bike and you need right gas tank off and you need to drill a hole in airbox to access it.
    You may need to loosen the throttle body assembly to see where to drill the hole properly but maybe you can see if you remove the triangle access cover on the rght side of the airbox.

    Tighten TPS screw - be careful - it is easy to strip.
    Plug TPS adjustment drill hole on airbox with a rubber plug.
    After TPS adjustment you can turn off the bike.
    Close Tuneecu software.

    Then turn it on again with Tuneecu connected and watch to see the TPS voltage (without motor running). After stepper motor cycling the TPS voltage will be a bit higher (like 0.75V on my bike) since the stepper has moved the throttle position a bit open from zero position (0.6V) to make the proper idle setting (0.75V). Try moving throttle slowly from closed to fully open and watch TPS voltage change from idle (0.75V) to maximum open setting (3.6V on my bike). Also watch that the TPS voltages change smoothly as you slowly move throttle to full open position. If it does not then this might indicate a bad TPS.

    Start motor and listen for idle. Let it warm up and cycle throttle through open and closed position and listen for motor running properly especially a nice idle.

    Hope this works.
    #6
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  7. NKL

    NKL Been here awhile

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    TPS measurement and adjustment is done with a hot engine not cold.
    #7
  8. Sumi

    Sumi Long timer

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    Wow, thank you very much! I’ve did it without setting the stepper to full retraction, but might go back tomorrow anyway cause I’m now afraid that I might have overtorqued the bolt...

    Bike runs okayish now, and I’ve tried to record the process, so might put it on youtube later.
    #8
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  9. DELTATANGO

    DELTATANGO Motorcyclist and Dog Walk

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    Good grief. I have never monkeyed with this on my 950/990 swap.

    Do I need to? Does it matter? It this why it is is switchy at 3k?
    #9
  10. zeegman

    zeegman Been here awhile

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    This procedure is more about getting proper idle adjustment and only applies to 990 as far as I know.

    If you already have a nice idle but snatchy throttle at 3k I don't think this will help your situation much.

    Maybe a different mapping would help your in your case.
    #10
  11. Imachimper

    Imachimper Shunpiker Extraordinaire

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    "Tighten TPS screw - be careful - it is easy to strip."

    I am generally pretty good at not stripping out things, but with my new hole just off center from the correct location, strip it I did.

    This had to be fixed. Since I now needed a new fastener for the TPS I decided to change the style to a 6 point M5 80 pitch adding a small aluminium spacer for ease of access.

    Now I can adjust the TPS without having to take the tank off. A quick reach in with an 8 mm open end and done.[​IMG]

    Sent from my SM-G920V using Tapatalk
    #11
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  12. Zuber

    Zuber Zoob Supporter

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    That lengthy procedure for adjusting the throttle cable is correct, but not for adjusting the TPS voltage. The 0.600v is set when the engine is hot and at an idle.

    It is easier to use a volt meter than TuneECU because the response is quicker. Start the bike and warm it up while watching the TPS voltage. Kill the engine and turn it back on. Then loosen the screw and turn the sensor. The voltage will change when you tighten the screw. Turn it off, turn it on, start the engine again and check it. Repeat. If you change it while the engine is running, the idle will go high or low. Turning it off and on will reset the ECU and the idle speed. This is why you should never have your hand on the throttle when you turn on the ignition or it will disturb the idle settings.
    #12
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  13. Sumi

    Sumi Long timer

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    Thanks guys for the input. My TPS is still holding it great at 0.6V hot so I guess I've nailed this project:))

    Other question you might know about: This is a 2006 EU 990, which I can start while the rpm gaguge is self-testing, idle stepper is doing its thing after turning the key / kill switch on. I've heard that from 2007 you can not start the bike until this procedure is done. If this is true, does anyone know if I can mod my 2006 to behave like a later model, so I won't accidentally start the bike until the self-tests are completed?
    #13
  14. Imachimper

    Imachimper Shunpiker Extraordinaire

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    Is there an advantage to loading the EU maps to a US bike? 2010 990 ADV ABS with only the canister removed.
    #14
  15. Zuber

    Zuber Zoob Supporter

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    I remember that the EU maps have a smoother ignition curve and the Charcoal Cannister valve is disabled. Otherwise, they are about the same. Just use Compare in TuneECU and look at the curves.
    #15
  16. guns&coffee

    guns&coffee Long timer

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    I pulled my carbs on my 07 950 SE to re-jet and adjust the floats. Pulled the TPS to give the cabs a good cleaning while they were off. I have the TPS Tool to tune the TPS before I put the tank back on. (doesn't appear that I can adjust it with the tank on) The tool reads 2.07 with throttle closed and 3.7 with throttle open. Doesn't seem to jive with the number from KTM using a volt meter and pushing the testers into the back of the plug. Has anyone used the TPS tool and should I be going about this differently? I've read above where it was done with the motor hot. Wonder if using the TPS makes a difference. It doesn't say anything in the instructions about testing with a hot motor.
    #16
  17. Boatman

    Boatman Membership has it's privileges ;-) Supporter

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    This may help..... https://advrider.com/f/threads/weird-reverse-tps-voltage-reading.1202298/#post-31444805
    #17
  18. guns&coffee

    guns&coffee Long timer

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    Wires are hooked up correctly. There is plug/pigtail that come with the TPS tool. The bike has no emissions stuff on it, a CPR filter, and Remus exhaust. I have no idea what the previous 3 owners may done with the bike. I've pulled the sensor off and worked the throttle to reset it. Also checked the sensor with it off the carb. There it measures around 0.05 (again that's disconnected from the carb)
    It's as though the flat pin sticking out of the carb is not positioned right.
    I' have to make a new fuel line tonight before I can put the tank back on. The old one is pretty rough. (07 with over 40k)
    Any thoughts.
    #18
  19. tinwelp

    tinwelp Professional Idiot

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    As you're getting a good number with the throttle wide open AND presuming your tool is professionally made (and therefore made correctly... which may be a dumb assumption, but I'm wearing my optimistic hat today), I'd strongly suspect your TPS is actually a lot broken. If you want to be absolutely sure, remove your tool and measure the voltage directly at the connector as noted in the thread provided by Boatman. If it's still wrong, buy a new sensor. They don't last forever and they really make a difference to how the bike runs.

    Cheers... Paul
    #19