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Speed sensor ques

Discussion in 'ECU's, Electronics, and Tuning' started by cheese9988, Aug 19, 2004.

  1. cheese9988

    cheese9988 Senior Member VIP

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    I don't know if anybody will know this....will the ecu throw a code if it thinks you are going lets say 50mph all the time, even when you are at idle or driving around at any other speed?
     
  2. pissedoffsol

    pissedoffsol RETIRED

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    lol umm...

    the speed sensor is mecahnical. theres a notch on a spindle thinggee which gets turned by the tranny.

    so, unless your sitting there spinning it, or the insides of your tranny are moving, its not possible
     
  3. radnulb

    radnulb Senior Member

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    the VSS is simply pulsed to ground 4 times per revolution of the wheels. Someone on PGMFI actually made a really simple device that removed the revlimiter by sending a bogus speed signal to the ECU above 100mph. Sending a fixed frequency pulse is probably not the best idea, especially considering how easy it is to simply pass through low frequency signals and cap their frequency to control maximum speed.
     
  4. pissedoffsol

    pissedoffsol RETIRED

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    well, yeah. the thing i described above spins, and hits some kind of contact point or something inside, which then gets translated into electronic pulses to the ecu.

    there are two main types of sensors-

    pulse and voltage
     
  5. cheese9988

    cheese9988 Senior Member VIP

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    I know that, I was thinking that I could trick the computer into thinking I was going say 50mph all the time with a simple 555 timer or something. I'd just put the scope on the output from the speed sensor and see what the pulse was. I just wasn't sure if it would make the computer act wierd if it was constant. I could build it to go up and down at a fake rate, but that would be more work.
     
  6. radnulb

    radnulb Senior Member

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    or you could use the design to pass through the signal until it is too high and use the design that is already done instead of reinventing the wheel...
     
  7. cheese9988

    cheese9988 Senior Member VIP

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    :p Eh, 555 sounds just as easy, I'll just plug the scope into a power inverter and see what the pulse looks like when I drive around.
     
  8. radnulb

    radnulb Senior Member

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    it varies in speed. you'll run into a few minor issues in terms of fuel economy stuff and idle if you disable it.
    You also won't be able to use a VSS-based 2step limiter.
     
  9. cheese9988

    cheese9988 Senior Member VIP

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    But it won't affect driving preformance that much do you think. You probably know more about the ecu's than I do.
     
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