Intermittent power loss

Hi Cody

Not much to go on.  How many hours on the engine?  What type of switch, toggles or key rotary?  Have you tried the B side turned off first?  The A and B are independent circuits.  At cruise power there should be no MAG drop, that should only really be something you see at your 4000 RPM engine check.  

A good start would be to check all connections from the stator up to the modules.  Also check the connections of the trigger coils to the modules.  Each module powers 4 plugs and that is split between 2 triggers and 2 coils for each module.  Look into the heavy maintenance manual and find the correct wire chart for your engine type.  Always check your grounds from the modules to the intake manifold to be sure they are clean and have good contact.  Look for any signs of wire vibration where they connect to the ground rings.  

Cheers

Thank you for responding. I was able to get it to occur on the ground and what I’m finding is that one of the ignition sources is coming on and off line periodically. I just need to wait for an RPM drop indicating one of them is no long powered. It was channel A.  I have rotary key and to troubleshoot, I swapped the horizontally mounted connectors and the failure swapped from the key being in the “L” position to the key being in the “R” position. I put them back and then swapped the vertically mounted connectors and the failure went back to the “L” position. I’ve checked all of the wires for continuity and they seem to all be fine. I’m just trying to wrap my mind around if I swap the horizontally mounted connectors and the failure position swaps with it, that would indicate that everything upstream of the ignition modules is functioning, so I think an ignition module is starting to fail.

Cody,

Have you gone to the videos page on this site and watched the “Troubleshooting the Rotax 912 ignition system” video?

I sure did. I found it very helpful in coming up with how to isolate components and did all of the steps they described plus a few more in regards to wiring. Unfortunately, at the end of the video I didn’t see any explanation as to what the results indicate, just to give them a call. I’ll plan to do that today, but it seems like I’ve isolated the CDI module because the problem follows that A module regardless of which switch it is on and what else is on that switch downstream.