At cruise speeds the throttle control on my 912is has dead zones.  For instance, at 5100 rpm, advancing the throttle initially has little affect then jumps 150 RPM to 5250 or even 5300.  Advancing past the desired setting then back down helps but often I just have to accept an RPM that is close to what I’m shooting for.  Have others noticed this on the injected engines?

  • Re: Throttle Control Dead Zones

    by » 3 weeks ago


    I have the same issues. 


  • Re: Throttle Control Dead Zones

    by » 3 weeks ago


    I suspected that this was a characteristic of the fuel injection design.  Thanks for the reply.  


  • Re: Throttle Control Dead Zones

    by » 2 weeks ago


    As you increase the throttle, you are releasing cable.

    If the cable is sticking, it will go slack until the throttle spring pulls it tight again with a sudden change in RPM.

    Reducing throttle will be smoother because there is solid tension on the cable during throttle down.

    Have someone cycle the throttle while you observe the arm on the Throttle body move. Engine OFF!

    Move it very slowly a millimeter at a time and confirm the throttle is moving in unison.

    It is not a fuel-injection "Characteristic".

    If you move the throttle open even the slightest amount, you will change the MAP in the Airbox ever so slightly.

    This will result in the engine's speed varying ever so slightly in suit.


    Bill Hertzel
    Rotax 912is
    North Ridgeville, OH, USA
    whertzel1@yahoo.com
    Clicking the "Thank You" is appreciated by all.

    Thank you said by: Jeff Blakeslee

  • Re: Throttle Control Dead Zones

    by » 2 weeks ago


    Thank you Bill, that makes total sense and I will check that out tomorrow.  


  • Re: Throttle Control Dead Zones

    by » 2 weeks ago


    It’s normal and it is part of the electronic fuel injection. The jump you see is the band at about 97% throttle where the engine switches from eco to power mode.  The throttle I just gave you is sensed throttle position by the ECU not actual throttle position.  The sensed position is much less than the actual full butterfly valve movement.  Try this when on diagnostic mode In the BUDS but also watching the butterfly valve on the throttle body.  Anyway the fuel flow jumps radically.  Check the ops manual you will find several charts on it.  Btw it also does this when only one lane is on or when you have a major fault.  Sometimes during lane checks the RPM will actually rise then once both lanes are back on it will decrease back where it was.  The mixture is just going full rich and thus more power.  It’s similar to lycoming and continentals where you don’t want to run at 75% power at lean settings. 

    If you don’t believe me check your data there’s a mode parameter in the data set that either 1 or zero for power versus eco mode it will switch at about this spot where you see the jump and it will jump about 100-150 RPM

     


    Thank you said by: Jeff Blakeslee

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