Basic description of Generator and Lane system operation

Just another note for all.  In an injected engine the "mag" check normally will not drop RPM.  Several things are going on.  With our legacy ignition engine each spark plug is off to the side, not in the middle of the cylinder.  The flame front will expand slightly slower to fill the cylinder in a single plug check (mag drop) due to this factor.  

In the injected Rotax we have 2 ECU.  One is full of sensors and allows the engine to have an ECO mode as we are aware.  This is Lane A.  The other, Lane B, runs almost entirely on a map, it has all the presents for RPM and fuel flow.  It is the default lane if there is sensor failures so it is always on the rich side for that reason.  (the ECU connections tell the story, Lane A has 2 large connections and Lane B only 1) Generally in the injected engines you will actually see a slight increase on Lane B only running in a MAG check at 4000 RPM.  Engines running in mid range like this like to be a bit richer so this is normal.  The important thing is you can run on each lane and it will be smooth, dont worry about drop. 

Cheers

Thanks RW, that fills in some blanks for me and fits with my thinking regarding how the system functions.  

That’s interesting Jeff. Thanks.

What seems odd to me either way is that if, when a lane switch is turned off the other lane can’t/doesn’t control the off-lane’s coils/injectors, there would be an issue if one of the on-lane’s injectors or coils failed. There’s a perfectly good injector/coil sitting there from the other lane and now it can’t be used (even though when both switches are on both lane computers can control all the injectors/coils). Not sure why Rotax wouldn’t want the working computer to still control both lane’s systems.

Two points that need clarification to make sure I have it right:

The fuel pumps run directly from the fuse box with the minus/ground switch on the panel but need to be activated by the ECU to ground only when the ECU is energized via momentary start power, ECU emergency switch or ECU A or B engine running. That is why the fuel pumps need the ECU power to run although they run directly from the fuse box.

If generator A fails, we get an A lane light on since the ECU cares/monitors generator A for the engine. We would see the buss voltage go from 13.8 to 12.8 and decline over time. If generator B dies, we will not see any lane light come on but similar buss drop in voltage from 13.8 to 12.5 as generator B switched the power the engine and stops the battery charging/buss voltage.

Do I have this right ???????????