D120 problems

[jimgreen]

I've got about 3 years and 190hrs on a Dynon D120 and it has been trouble free and a delight to use.
Starting about 3 months ago some of the indications have become unstable.
Initially two of the CHTs were jumping around. Then two EGTs were reading low.
The fuel tank indications jump around below about 8 gallons.(capacitive)
Now the oil temp has started to jump around.

The engine runs strong and vibration free. Seems like too many things at once to be just poor connections.
Did a run-up this pm and it all works fine, but in the air after cruising for 10 minutes or so the instability returns.

I thought perhaps one of the large Dsubs on the back was loose, but it's all rock solid.
Before I start tearing it all apart and chasing red herrings, I thought I'd ask the Brain Trust for any initial impressions and recommended trouble shooting.
Thanks guys.

[flyinga]

The Dynon sensors seem to fail after a few years. I'd change the bad reading sensors with good ones and see if the problem moves to those cyulinders.

[blueflyer]

check your D120 grounds. Poor ground will make your readings jump around. I seem to recall a test you can run with an ohm meter that is spelled out in the D120 installation manual to make sure you have a good ground. I'm just pulling that from memory, but it maybe worth a skim through the install manual to see about that.

[jimgreen]

Thanks for replies. Ground for D120 is good. So is engine/firewall/battery.
Hard to believe so many sensors are giving trouble all at once, but I'll try swapping lines over to isolate any bad sensors.

[Jesse]

See if somebody else has a D120 you can plug in to see if the problems follow the unit or the plane.

[jimgreen]

Great idea Jesse. I'll see if I can find someone.