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All of a sudden, when the rpm on 912ULS reaches 4500 rpm the indication becomes very erratic. This has been working ok for years and now all of a sudden this starts. This started out as a problem with the oil temp in flight indicating below 220 deg. the green arc on the rpm's would narrow giving a yellow warning that the rpm was too high for a cold engine. But now I do not get a narrow green arc on the rpm even when the engine is first started. I replaced the oil temp transducer but to no avail. I am wondering if I overwrote the EFIS setup file by mistake. I don't think a Rotax 912 requires a resistor but don't know for sure. Any help would be appreciated.

  • Re: 912 ULS Eratic RPM on D-1000

    by » one month ago


    I had a very similar problem with my tach after years of working fine. A resistor was suggested and I looked up the size and installation in the Rotax 912 installation manual and it said it might be needed and gave the details. I installed it and no more problems.


    Thank you said by: RotaxOwner Admin

  • Re: 912 ULS Eratic RPM on D-1000

    by » one month ago


    I found a loose plug and was sure I had fixed it, but NO. I have been told to use a 60K OHM resistor in series. Did you just install it inline or did you use a mountable? Do I need two resistors, one for each electronic module?

    Thanks.


  • Re: 912 ULS Eratic RPM on D-1000

    by » one month ago


    I installed mine inline. You only need one in the single line for the tach.


  • Re: 912 ULS Eratic RPM on D-1000

    by » one month ago


    The resistor in series with pin 32 of the SV-EMS-220 solved the problem. Now I can't shut the engine off. It keeps running and I have to shut the fuel off to get it to stop. I saw where you have to run the other side to ground so I did that, to no avail. Any ideas? I take the resistor out and it will shut off correctly. I left the wire connected when I grounded it so maybe I will try and cut the wire going to pin 33. Dynon tech support was no help.


  • Re: 912 ULS Eratic RPM on D-1000

    by » one month ago


    That resistor in the tach signal line to the Dynon SV-EMS-220 should have absolutely nothing to do with shutting the engine down. In the process of installing it you must have done something to mess up the ignition wires (one or both) to your key switch. If the ignition wires (both) are grounded the engine WILL shut off, except maybe for the rare condition of glowing deposits in the combution chamber.


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