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We are integrating EMU (Engine Management Unit) from M/s Stocks Flight Systems with Rotax 912iS Engine. 

Question:

We found two Fuel flow rate parameters on Lane A & Lane B in CAN ID 524 & 588 respectively.

Could you please explain how these two fuel flow rates computation done by ECU internally, where-in single fuel pump used for the engine? Also, we found, fuel flow rate values in lane A and lane B are independent of each other.

INFO: EMU displays, the addition of these two lane data (Lane A & Lane B in CAN ID 524 & 588). Range of display: 0 to 50L/Hr

 

Please explain the principle behind the computed output parameter of fuel flow rates

 

  • Re: Fuel Flow Rate on CAN channels

    by » 10 months ago


    Each cylinder has two fuel injectors.

    The injectors alternate injecting on alternate piston strokes.

    One injector is controlled by each lane A and B.

    There is NO actual flow meter.

    The ECU calculates the equivalent flow rate based on the engine rpm and the pulse width duration that the injectors are firing at.

    Each lane reports the amount of fuel it is delivering.  ~50% from A and the other 50% from B.

    If one lane goes down, the other lane takes over on every cycle.

    At that point, the bad lane stops reporting and the good lane's fuel rate will double as it is now operating 100%.

    The fuel flow is sent on the can bus in the form of pulse counts equivalent to a mechanical paddlewheel type fuel flow sender.

    The K factor is typically 3500 pulses per gallon.


    Bill Hertzel
    Rotax 912is
    North Ridgeville, OH, USA
    Bill.Hertzel@Yahoo.com
    Clicking the "Thank You" is Always Appreciated.


  • Re: Fuel Flow Rate on CAN channels

    by » 10 months ago


    Thank you for your quick reply.


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