Throttle Position Sensor???

Discussion in 'Crazy-Awesome almost Dakar racers (950/990cc)' started by mattawa88, Jun 23, 2007.

  1. mattawa88

    mattawa88 It's all about the Ride!

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    My 04 950 has developed an intermittant backfire, usually at about 3800rpm, just as I begin to roll on the throttle in the apex of a corner.
    It's not a miss but an actual backfire.
    Upon testing the TPS, I find that the voltage is all screwed up. My voltmeter reads 4.4 volts at a throttle closed position and 1.1 volts at full open. The book says .6 volts at closed and 3.6 at full open.
    Anybody else had troubles with the TPS?
    I had a Yamaha WR400 that had a TPS go out, but it was a lot more evident than this.
    Anyway, I ordered a new TPS, just wanted to compare notes.
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  2. StevenD

    StevenD Hmmmm, dirt!

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    as soon as you got the EPC disconnected or removed you can and should remove the TPS as well. just disconnect it and toss it away. hell. i got 2 here you can pick up for free.
    ONLY the EPC crap uses the tps sensor.
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  3. K2m

    K2m ....58....

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    Are you sure about this Steven? I thought that it would influence the ignition map 3D timing instead of 2D timing, but perhaps it is not that advanced. This would be a good solution for the FCR not having a TPS:D
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  4. PowerCell

    PowerCell Manufacture

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    +1
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  5. K2m

    K2m ....58....

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    Thanks Steven, Ken. It does not matter how much you know about these bikes...... you never stop learning. This web site is a great resource:freaky

    We should extent the Dark Ages up to the time before we had the Internet.

    This has solved the biggest problem that I faced fitting FCR carbs.

    Thanks again guys.
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  6. Flanny

    Flanny Flanny-it-up!

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    I've got my carbs out right now, and they will be going back in in about three days...so the timeing is perfect.

    Mine is an 05.5 950.

    Are you guys actually saying that I can remove the sensor and the wires altogether?

    Please confirm.

    Thanks.
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  7. PowerCell

    PowerCell Manufacture

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    At low RPM's and heavy engine loads, the TPS will signal the ignition to retard the spark in order to reduce the chance of detonation...
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  8. StevenD

    StevenD Hmmmm, dirt!

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    Yes: on a Husq for example.

    NO: On the 950 the TPS is only used for the EPC system. (you know.. inject air to slide's in carb when sudden full trotle in 2'nd or 3'rd is activated ;) )

    It is NOT used to retard the timing in any situation or anything.
    so: EPC gone == remove the TPS to!
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  9. PowerCell

    PowerCell Manufacture

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    This is incorrect. It is used to retard to spark to prevent detonation, but is not needed once the smog equipment is removed. On heavily loaded bikes you may wish to leave it connected, even with the EPC removed, just as a safety measure.
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  10. StevenD

    StevenD Hmmmm, dirt!

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    In that case my source is wrong (ktm factory tech) and the effect is so minor that dyno draw's cant show the diffrence.
    How do you know of this?
    Mine has been off for 15000km's now, no ill effects, well.. no effects at all :)
    #10
  11. PowerCell

    PowerCell Manufacture

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    I asked Sean McLaughlin last Friday afternoon at the Adventurer Rally in Mammoth. He's the head technician for KTM of North America.
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  12. K2m

    K2m ....58....

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    Do you have your TPS hoked up to your FCR's Ken?
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  13. PowerCell

    PowerCell Manufacture

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    Hey Rory...

    No, I don't run the TPS. The SE is fairly light, and with proper jetting, won't suffer from any detonation issues.

    BTW - here's the AP bleed jet mod you have yet to do. Sudco doesn't even know about this one... :D



    [​IMG]
    #13
  14. ktmkev

    ktmkev Adventurer

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    This is straight from the repair manual:


    "If the throttle grip is opened all the way (Which the ECU recognizes via the TPS) at a certain speed (or a certain number of revolutions) in 2<sup>nd</sup> or 3<sup>rd</sup> gear, the ECU activates the ground control of the EPC valves.


    Subsequently, the EPC valves will open an air connection to the carburetor diaphragm covers. A controlled amount of fresh air can be sucked into the space above the diaphragm, reducing the vacuum over the carburetor diaphragm.


    This causes the carburetor slides to open more slowly resulting in a lower air-gap area to be sucked in through the engine. The engine performance and noise are significantly reduced.


    NOTE: If the EPC valves are disconnected, this will not influence the other systems."

    It says nothing about timing, and it says it's ok to get rid of it.

    EDIT:
    My repair manual is for a 2003 bike, and mine is a 2006. I don't think my bike has the epc, but it does have the tps. So what does it do???
    What year of 950 adventure has the epc??
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  15. K2m

    K2m ....58....

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    You are missing the point........... Have a look at the adjustment procedure. This position sensor is some what over engineered for operating the EPC. A simple switch would have done. This sensor is there to retard ignition timing when the engine is under load. I have tuned a few car engines using programmable management systems and this is exactly what a TPS does.

    Ken has a good point when he feels that he can live without a TPS by using high octane fuels and careful attention to jetting. At least he will have the option to use the low octane map. Octane is a fuels ability to resist detonation. A problem on high performance engines as one seeks to find the limit.

    It is possible to fit the original KTM TPS to the FCR's as it is a standard Keihin part. It requires a different shaft and a different cable connector. About $200AU. The guy who is suppliying my FCR's feels that it will be cheaper to modify the original shaft.

    Thanks for pointing this out Kev, but this was the first place I looked to analyse when the thread started.

    Your edit says it all. Good more evidence for it use. Thanks Kev
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  16. K2m

    K2m ....58....

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    I will not ask........... I will not ask........... I will not ask.......... I must not ask...........


    You teaser Ken:lol3
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  17. ktmkev

    ktmkev Adventurer

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    I don't have epc, but I still have the tps, so it must be used to retard the timing.

    What I would like to know is: Are you going to get crap in the shaft area where the switch came out of, because it has an o-ring seal on the inside of it? Or is that o-ring there to protect the switch from crap???
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  18. PowerCell

    PowerCell Manufacture

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    Who are you asking Kev? K2M and I don't run the factory carbs.

    I would suggest leaving the TPS connected. You're not going notice any performance increase, and it's nice to have the added protection.
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  19. ktm950se

    ktm950se Banned

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    Greetings,
    Any chance, that along with detonation control, this function was also designed to reduce too much power being applied to the rear wheel upon quick throttle openings? The Kawasaki ZX14 has a second set of butterflys (not connected to the throttle) that open upon a computer controlled system to prevent abrupt power at low rpms. The ZX14 guys all remove the "flys" upon buying the bike and report mega increases in bottom end...

    ktm950se
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  20. Northbound

    Northbound Adventurer

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    Ah! Yeah. It's just we're putting new coversheets on all the TPS reports before they go out now. So if you could go ahead and try to remember to do that from now on, that'd be great. All right!

    :rofl So, Peter, what's happening? Aahh, now, are you going to go ahead and have those TPS reports for us this afternoon?
    #20