First question; ever since new, according to my savvy analysis data, there is a consistent difference in EGT's. Cylinders 3 and 4 run  the hottest while 1 and 2 are colder. There is a consistent spread of about 60F between the coldest(usually 1) and the hottest (usually 4) - is this normal?


Second and perhaps more serious problem. In hotter summer weather, if I spend too much time on the ground and let heat build up in the engine bay, I get a solid red light on lane A  and a message on my Dynon skyview - land immediately. and a reference to a problem with coil 2.

However if I cycle the lane A switch and take off  immediately before the light returns, there is no further problem. I cannot see any difference in the normal EGT behaviour of any of the cylinders when the light is on, so I don't think its a coil breakdown. Everything seems to be working with no power loss.

I'm guessing that high underhood temperatures are causing an imtermittent fault somewhere. I will try and downlaod the ECU logs and post  the details here. I dont know if I need a new coil or if there is some other problem, perhaps a loose connection. I would appreciate your diagnosis.

  • Re: 912 iS Sport EGT Differences and Coil Problem?

    by » 4 months ago

    A 60 degree variation between EGTs is typical and nothing to worry about.  This can be as simple as sensor error, a slight differences in airflow through the airbox to each cylinder, or airflow differences in the engine cowl.  My 912iS has a similar variation.  As far as your lane warning light, it’s reasonable to suspect it’s heat related, but you would get more help here if you post the BUDS Fault log.

     A coil error can be a problem with the coil itself, or downstream of the coil.  So check the connections at the coils, and your plug wires, making sure the connections at the spark plug boots are tight.  The boots screw on, so you can give the boots a right hand twist and make sure they are tight.  If the connection is loose and won’t screw down tight you can remove the boot, snip off 1/4” of the plug wire then screw the boot back on.  

  • Re: 912 iS Sport EGT Differences and Coil Problem?

    by » 4 months ago

    I downloaded the engine data into a log file. Who do I send it to? How do I send it?


    I ran the engine again to see if I could duplicate the problem..

    Sure enough after a few minutes the coolant temperature reached about 87C, then I got a "land immediately" message on my Dynon Skyview and a steady red light on Lane A. I recycled the Lane A switch and increased engine rpm to supposedly increase underhood cooling. The light stayed off.  I do not know what the engine is doing.

    I am becoming extremely uneasy about the serviceability of these engines because the softare and diagnostic systems seem deliberately complex and inaccessable  to a builder. Having to spend $1000 for a proprietary dongle just to read the logs and still not be able to interpret them is not optimal because we have no idea of the severity of the faults and rotax doesnt seem to want to tell us anything without paying $$$$ for information.

  • Re: 912 iS Sport EGT Differences and Coil Problem?

    by » 4 months ago

    OK, calmed down and done a little more research and a look at the log file.....


    The failure message i get that is different from all the junk that seems to repeat itself is:


    "Lane A failure actuator (ignition cyl 3 and 4) -TPU test - nominal current not reached"

    Can anyone please explain what that means and what to do about it?

    Also, if that is  the fault, by cycling Lane A and the light foes out, is the igntion working correctly now or has the ECU locked it out and is just relying on lane B plugs for those cylinders?


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