Oliver:
The primary cause we've seen from EGT and CHT issues is the connection between the CHT/EGT wires on the sensor, and the harness (stiff brown wire). We suggest you re-crimp or replace those connectors.
SkyView displays a Red X over a engine sensor reading when that sensor's output is outside what is considered a normal range. In the case of your #1 and #4 EGTs, those sensors could be failing, open-circuit (or possibly shorted) when cold due to thermal expansion and contraction. Likely if you replace the #1 and #4 EGTs, that situation will be resolved.
Couple of weeks ago I noticed that #1 EGT would show a red X when the engine is not running (EGT at ambient temperature). As soon as the engine starts and the temps go up the red X would disappear and it would seem to work fine without any problems for the rest of the flight. Now a few weeks later the same started happening with #4 EGT. I just checked all the wiring and can't find anything wrong with that. Any suggestion on what's broken and how to fix it?
Thx
Oliver
