Ignition Check Anomaly

Sean,thanks for the reply.  The answers to your questions #3 and #5 are in my original post. As for the others...This has been a recent phenomena, past 4-5 flights.  I preheat my plane but ambient temps have been 30-40 F so I guess winter conditions apply.  Post-landing taxi is short, less than a minute.  As stated before, 4000RPM runup is done prior to takeoff, on runway itself.  That's where problem is apparent.  I will check for less-than-tight connections and grounds as you suggest, although they looked good when I had it decowled for the new plugs and boots.  I appreciate your suggestions and hope maybe you or someone else can tell me if there is a failure mode of the module itself that resembles this.  I had a module crater last year; went completely dead.  Flew today; exact same behavior.   Jim

Roger Lee wrote:

Explain the difference between a mag check at 3500 vs 4000?

No idea - I do 4000 RPM.

Could be something to do with best spark generation between certain RPM range eg 4000 - 5500 RPM

Seems to me the likely answear is mainly consistency ie if as an individual and as a group (Rotax drivers) the same procedure is followed for an expected outcome (RPM drop) this reduces the chance of an anomaly due to different inputs (eg ignition check at arbitrary RPM)

Graeme your suspicions of the module may be correct.

2 Ways to check -

1) swap the connections between the plugs of each ignition module and see if the mag drop changes to the other mag.

2) warm the modules up with a hair drier before first ignition of the morning.

I also seem to recall the module internal capacitors presenting with these symptoms on occasion.

Regards.......Chook.

Chook,  Thanks for the ideas.  At what point do you switch the connections?  I don't want to mess with those tiny little plastic junction boxes if I don't have to.  Will try hair  dryer idea.  I had heard that too much heat was bad for the modules so guidance would be appreciated as the last one cost me $900.   Jim

Jim,

Swapping the plugs on the modules isn't hard and not a big deal so don't be afraid to check this.

Use an ice pack instead of heat. You're right. too much heat can cause damage. take a one gallon baggy with some ice. Not too full because you want it on top and then wrap around the sides as best you can. Let it sit for 30 minutes and then try a start.