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  1. #1

    MSX 140 - High idle and TPS measurement not right? Help Please

    I have a 2003 MSX 140 and the tps reads 4.97vdc at an idle. It should be around .350vdc according to the manual.

    Sounds like it has an air leak but I have checked and cant find one.

    Anyone have any issues with the tps? I can move the tps and voltage does not change. Sounds bad to me.

    Thanks for any help.


  2. #2
    Click avatar for tech links/info, donation request K447's Avatar
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    Welcome to the Hulk

    On which pins are you measuring the TPS voltage?

    Does the engine respond to turning the TPS (squeezing the throttle)?

    TPS do go bad, it is fairly common. Not in the manner you describe, however.

    Replacement TPS have been in short supply for months, but additional parts are expected to be manufactured sometime soon. Not sure exactly when they will become available.

    There are some new TPS for sale here and there, you just have to hunt around for them.

    Click my signature links for more info, under Ficht and MSX

  3. #3
    I am on the black and red and it stays at 4.98v and never changes when you move the throttle. Engine does not change when I move the tps.

  4. #4
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by eperform View Post
    I am on the black and red and it stays at 4.98v and never changes when you move the throttle.

    Engine does not change when I move the TPS.
    The TPS is powered by 5 volts (from the EMM) on the Red wire. Black is ground.

    The TPS position signal is on the center pin (White or White/Green).

    Check for dielectric grease on the connector pins (both sides). The pins should be clean, with NO dielectric grease on any part of the pins. The only place for the grease (and just a thin film) would be on the rubber seal.

    The TPS requires a completely clean metal-to-metal contact at the pins. Sometimes the hollow metal socket contacts need to be gently squeezed with fine needle-nose pliers to ensure a tight fit over the mating pins.

    As a test, unplug the TPS. Engine should start and idle right at 1150RPM. It will NOT respond to throttle of course, but the idle should be correct.

    Make sure the throttle cable has just a little slack so the throttle shaft rests against the mechanical stop. The EMM calibrates itself to the TPS signal at idle position, and this won't happen properly if the TPS is held off the idle stop.

  5. #5

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    What is the correct measurement of the TPS on a MSX 140? I built a TPS tester and am going to check it out this spring. My 140 will go to 6600-6700 then fall off to about 6400-6500. Plugs are very black and foul easily. Will not start when I pull it off the lift and taknig cover off (cold) and it takes about 1 minute of starter to fire it then it smokes for awhile, like it was flooded out. I have an overmolded new style TPS about 2 years old. Questions.

    1.) What is spec.
    2.) If out of spec., how to you adjust
    3.) Is the mecahnical stop adjustable?
    4.) With a TPS tester and 5V battery, can I not do it w/o motor running just like I do on my Polaris CFI Sled.
    5.) What should fuel pressure be, I will check that too.

    Any other suggestions would be great.

  6. #6

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    ttt

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