EGT Probe reliability

[Norman_Joseph]

I have recently completed building my RV-9 with a Lycoming IO-320 engine and Skyview 10 system. During my first few hours of proving flight the EGT readout of the number 3 cylinder went off the clock with a big X showing on the scale end. We swapped the probe with the number one cylinder and it then seemed to work better for a few hours. After approximately 12 hours of total flight time both number 1 and number 3 cylinders EGT readouts started doing the same thing. I replaced the number 3 EGT probe with a new one and that cylinder now seems to be normal. I then flew the aircraft for 1 hour and number 2 cylinder is now doing the same thing. Number one cylinder is also still off the clock. I cannot believe that 3 probes have failed in the space of 18 hours of flight time. The engine is new as is all the ancilliary equipment and the probes are supplied by Dynon. Does anyone have any advice for me?
All CHT's are normal in flight.

 

[Norman_Joseph]

Here is a picture of the EGT readout.

 

[Dynon]

So the first thing we'd suggest doing is re-crimping the connectors. Intermittent connections are definitely one thing that could lead to erratic or offscale readings. Though EGTs do tend to wear over time, 17 hours is definitely too soon. Do you know when the EGTs were originally purchased, by chance?

 

[Norman_Joseph]

I purchased them early in 2012. Probably in March 2012.