Rotax 912iS Sport and EMS221

[Tuiliere]

Hi Dynon,

I just upgraded my Rotax 912 engine from iS version to iS Sport and I see that my SV show now a fuel consumption of one liter per hour higher than before. I think it is not the reality because this version is more economic than before.
So my question is : Do you have to make a modification in the SV system to adapt it with this new engine version ?
Sylvain

 

[dynonsupport]

Rotax tells us there are no changes needed between the iS and iS sport.

Are you reading fuel flow from mechanical sensors or the ECU CAN bus?

In the end, you can always check by flying for a while and then seeing if how much fuel you put in the tanks matches the fuel computer or not.

 

[Tuiliere]

Informations are coming from the ECU CAN bus. I am going TO make some tests and I inform you on this post.

 

[Dynon]

One question here: what are your fuel flow k-factors set to currently? Though you don't have the fuel flow sensors installed, this number can still be used to tune the fuel flow reading on the iS engine. Previously, I think that other iS owners have believed that the ECU value was under-reading by 10-15% vs reality, so, it's possible that they've improved the reading with the ECU tune, and so NOW it's actually reporting accurately.

 

[Tuiliere]

My fuel flow K factors is 63 000 at the moment. It was accurate with my (old) 912Is. I will make some test as soon as possible and tell you if I need to change this setting with the 912Is Sport version or not.

 

[Dynon]

So the default for the k-factor is 68000, and that's where you should see parity from whatever the ECU is reporting. So by having it at 63000, you'd expect a higher fuel flow. Try setting it to 68000 to start and see if that jives better with what you expect to see.