ECU Errors loss of percentage power and throttle position indicators

Peter,

Percent power and throttle position are both dependent on the throttle position sensor.  I’m guessing that Percent Power may also reference manifold pressure, but I would think the TPS plays a part.  So it would be easy to suspect a communication problem between the TPS and ECU.   That said, I would think that if there was a problem with the TPS you would get a flashing lane light.  Still, you could inspect the connection at the TPS.

Since you don’t have BUDS, I would start by going into the G3X configuration mode and looking at the system information page.  I’m going from memory, but I think from there you can select the Rotax Fadec (or maybe the GEA-24) and see a count of CAN bus errors and any active faults. The error count is an indication of the integrity of the CAN bus between the Rotax ECU and Garmin GEA-24. I have never seen any errors on my plane, but the CAN is equipped to handle data errors. Remember to turn on the start power and ECU lanes or the G3X won’t see them as connected and you will have a red X next to that device in the list.

If you are going to diagnose and work on the Rotax injection engines BUDS is not an option, it’s required. It’s a reasonably good tool and in this case both the system health page and fault history would be quite useful.  It’s expensive, but so is buying new parts you are guessing at.  

Thanks Jeff, that's useful analysis, I  will check the TPS connections.