915 Eurofox Bad First Start of the Day

OK so if it’s not a throttle position problem, I’d still like to understand why it’s difficult to start cleanly, or is that normal ?

Every 915 owner I know (at least a dozen) reports the same issue with difficult cold starts. One guy spoke to Lockwood about it and apparently Phil told him the throttle position recommended by Rotax in the OM is too high in his opinion. He recommends a lower throttle position for start, but I’m not sure how much lower. I’m calling Lockwood tomorrow about something else (bad EGT probe) so I’ll ask him for more details on his start recommendations.

Thanks Mike !

The reason for the higher throttle positions during starting (as shown in the operating manual) is that injected engines don’t have chokes to enrich the mixture. Instead, as the throttle position is increased, the throttle position sensor tells the ECU to provide a longer injector pulse, thus a richer mixture at low (cranking) RPM. You do have to be ready to quickly retard the throttle when the engine fires. Most EFIS have a throttle position readout based on the TPS. The Garmin G3X displays this in the upper section of the engine ribbon. Once the engine starts the display changes to the ECO mode indicator.  

Our Kanardia EMSIS displays the TPS position (and I checked it's consistent with what BUDS shows) but it's vastly different from the linear throttle position measured with a ruler. For example, if the rotax throttle position start chart calls for 60%, if this is set using the digital display, it corresponds to 14% measured at the throttle knob. We've tried starting using both the digital display or an estimated throttle control linear position and we still get the problem in the video :-(