The last two flights my #1 EGT has been fluctuating. Has anyone seen this? How often are you changing the Denso plugs? Any ideas? 180 hours/FX3
The last two flights my #1 EGT has been fluctuating. Has anyone seen this? How often are you changing the Denso plugs? Any ideas? 180 hours/FX3
The fluctuating EGT readings are likely caused by an intermittent open circuit of the ground wire between the sensor and the GEA 24. (I had a similar problem with a CHT sensor on my new FX-3)
You ask about plugs in the same post but I doubt spark plugs have anything to do with the EGT issue. I have not changed my plugs (FX-3 132 engine hours). Gaps were as new at first condition inspection.
Last edited by Andy; 09-01-2021 at 08:14 AM.
Agree, open circuit somewhere.
In regards to plugs, a bad plug (or associated wiring) is easily identified on run up.
For the CC340 on the EX-2, manual states to inspect and clean the plugs every 100hrs. I just replace the plugs every 100hrs because they are cheap (Sparkplugs.com, Rock Auto, ....).
Dan Arnold
KEUL
There is no loose wiring that I could find. I tested the resistance of the plugs. Plug from top of cylinder #1 was 6 times the normal readings of the other 7 plugs. The runup was normal, so this bad plug was not easily identifiable. I've ordered a new set. I expect that will fix the problem.
Thanks for the report. I had not realized that a misfiring plug would raise the EGT but here is an extract from a Savvy Analysis report that I received in my email today:
“If one of the #2 spark plugs had stopped firing, we would expect to see EGT #2 rise by about 50°F to 100°F and CHT #2 start to decline a bit."
Interesting, can't say that is intuitive from my brain on the EGT's. CHT's yes.
Dan Arnold
KEUL
It has to do with the flame front and time. Think of it this way, if you and your buddy were on opposite ends of a field and both lit the field on fire, it would take ~half the time to burn all the way across as compared to if you were trying to light the field afire all alone. Two mags is lighting the fuel air mixture (the field) on fire from both, opposite sides.
Inside the cylinder operating with one mag, the fuel air mixture takes more time to burn and, as such, it is still burning or was just burning as the exhaust valve opens. The exhaust going past the temperature probe is hotter and you get the higher EGT.
Got it!
Cheers,
Dan
Dan Arnold
KEUL