RPM signal converted to Variable resister question from noob

Discussion in 'The Projects Forum' started by Mag00, Mar 5, 2014.

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  1. Mag00

    Thread Starter New Member

    Mar 5, 2014
    Hi Ya'll, just found this site looking for a solution to a motorcycle ECU enrichment issue.

    I have a basic understanding of electronics.

    The challenge is to take a tachometer signal and tie it to a variable resistance to alter a lambda sensor output to a computer (ECU).

    I am in the discovery phase, (just starting LOL) and do not know what semiconductor or IC chip or arrangement of electronic components can do the job.

    The RPM needs to be read without bleeding much power off the wires running to the coil. I have taps on the wires for a dyno rpm reading.

    The engine runs lean at low rpm, and rich at high rpm. The lambda (02 sensor) sends a voltage signal to the ecu to correct to predetermined specs residing in the ecu. If I can change the resistance, thus changing the voltage in proportion to RPM, I think I can have a good solution.

    Unfortunately nobody has been able to crack into the ecu and upload new fuel and ignition maps, so a piggy back fix is the next best thing to a real programming solution.

    What semi conductor should I be looking at, or do I need to design something to do the job using transistors and other hardware? Been 30 years since I took electronics, maybe I need to crack a book again.

    Any suggestions will be appreciated.

  2. #12


    Nov 30, 2010
    Wrong website. Try electro-tech-online.
  3. Mag00

    Thread Starter New Member

    Mar 5, 2014
    Thanks much, I'll go take a look over there.
  4. MrChips


    Oct 2, 2009
    The owners of All About Circuits have elected not to host discussions of automotive electrical system modifications/enhancements due to safety concerns, the potential of legal ramifications and the possible circumvention of vehicle regulations at the state and federal level.

    This thread is against the AAC forum rules, Chapter 6, as seen here:

    This can be found in our Terms of Service (ToS).

    Automotive modifications of any kind are strictly forbidden. Therefore, this thread will be closed.

    Please try to understand the reasons behind this action, and feel free to browse and use the forums.

    There are other forums where you may be able to get some assistance.

    Good luck.
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