High EGT

Hi Sean

If possible switch the probes and see if the temp spike follows the probe or stays on the same cylinder.  Whoever supplied the probe should be able to give you the resistance settings for them.  EGT probes are notorious for failures from some suppliers, I always found issue with the China made K probes in years past.  

Cheers

Hi Sean

If possible switch the probes and see if the temp spike follows the probe or stays on the same cylinder.  Whoever supplied the probe should be able to give you the resistance settings for them.  EGT probes are notorious for failures from some suppliers, I always found issue with the China made K probes in years past.  

Cheers

I'm with RW on switching the probes to check them out. Plus like he said they do go bad and it's easy to just swap them out. Dynon told me once they should last 200 hours and beyond that they weren't guaranteed, but some do last may years and hours and some don't.

Or for $41 you can just buy a new probe and replace it and that will tell right away.

https://shop.dynon.com/products/egt-hose-clamp-0-75-1-25-rotax?_pos=2&_sid=a0b790238&_ss=r

RW/Roger,

I always thought that thermocouples/EGT probes, when failing, give a low reading or just fail completely. This was a spike to high temperature & Dynon warning.

Yes, exactly.  Thermocouples only fail in ways that lead to low readings.  The temperature difference between the hot junction (at the probe) and the cold junction (at the gauge) generates a small voltage because of the Seebeck effect.  The only thing that can cause them to read high is if the gauge has a fault in measuring the local (cold junction) temperature, but you would see that immediately on start up with a cold engine. The most common failures to look for are high impedance joints (i.e. loose connections) or else the probe not making good contact with the exhaust.  These failures cause low readings..

I would have thought that the only thing that would increase EGT would be a stoichiometric fuel/air ratio - which is what you would want at cruising altitude if you had adjustable mixture.  Perhaps there is an imbalance in fuel flow at wide open throttle? 

Maybe the 912 is designed to run with a rich mixture?  I don't know..