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Thread: ?s about Motec

  1. #1
    hitman's Avatar
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    ?s about Motec

    Hey Pete,

    I have kind of a weird question that goes back to how the M400 was adapted to our SHO engines. I am currently in the process of trying to run an aftermarket piggyback fuel controller and am having a hell of a time getting RPM reference.

    Was wondering if you guys encountered anything out of the ordinary when getting the M400 to deal with the stock crank position sensor. From what I can tell it's a pretty standard mag-style sensor, but something seems to be odd or different about the signal range it operates in.

    I can successfully perform an RPM calibration and get a correct reading, but I seem to be having an issue with the piggyback retaining that calibration after a complete power down of the system.

    I have even tried tapping into the stock tach signal (thinking it was maybe a cleaner, or more standard signal for the piggyback to interpret) using instead the hall-style crank input function of my piggyback, and I get the same issue. It just seems so weird to me. Is there any advise you could offer? If not that's ok, I just though maybe you encountered some of this when you were adapting the M400 for our platform. Do you happen to know if the dash gets it tach signal from the crank position sensor or possibly from the cam position sensor? I would think it could be gotten from any sensor on the ski that "spins" but I'm no electrical engineer. I might be way in over my head.

    Thanks,
    Todd


  2. #2
    MoTeC Pete's Avatar
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    Hi Hitman
    Ok
    Here is what I know
    Crank has a relatively ordinary sensor on it, seems very run of the mill to me.
    What is unusual is the tooth pattern.
    Its 12 plus 1. So 12 evenly spaced teeth and 1 extra tooth close to one of the even teeth.
    This type of arrangement is common these days and ECU,s use extra and missing teeth like this to help give an update of where the crank is in its cycle.
    The ECU doesnt have a taco out put rather it sends information to the Dash via a comunication protocol called K Line
    This is a little bit like a CAN Bus or like that Blue LAN cable you have on your net worked computer.
    So this wire sends the taco info plus warning alarm levels and a few other bits and pieces.

    Hope that helps

    Cheers


  3. #3
    SHOBiz's Avatar
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    Was waiting for this reply.

    So, for his purposes another sensor could just as easily be used for position. Possibly as simple as a magnet attached to the coupler at the rear end and a sensor to pick it up. I assume the cam sensor is k line as well since he was not getting anything from it as well. So, he may need to address that as well.

  4. #4
    MoTeC Pete's Avatar
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    It depends on his ECU
    He should be able to piggy back the CAM sensor but it reads 1 pulse per 2 rpm so most ECU's probably cant work with that.
    Yes a seperate sensor and trigger wheel will supply an rpm signal, I would be nevous about the coupler as it screws on, this leaves the potential for a timing change in the future, if not being used for ignition then it should work.
    I would then have to wonder why all the effort for a fuel only controller as the real gains in these engines is via more ign timing.
    Any way not for me to wonder eh


    cheers


  5. #5
    hitman's Avatar
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    Hey Pete, thank you very much for the info on the crank sensor. Knowing this info about the stock crank and cam sensor may help me when trying to explain the issue I'm having to tech support.

    Hopefully I can get it figured out. If anything, it's looking more and more like a software issue.

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