Insight GEM engine monitor

[Guest]

I have an early insight GEM.  It is the orange color thing and just shows bars for the EGT and a black space for the CHT.  My CHT bars on cylinders 1 and 3 have both vanished.  I imagine that it is bad probes, but find it interesting that both on one side have failed.  Any recommendations as to where to begin troubleshooting this?  Should I try continuity between the CHT and the gauge?  What is the normal point of failure on these?

 

Also, only remotely related, this is the first airplane that I have owned that I have tried running LOP due to having CHT and EGT.  Is this a normal experience?  When I pull to lean of peak, say 50-100 degrees, it actually runs pretty smoothly, CHTs seem a bit higher but not in the "danger zone," maybe high 300s, but I take a big hit on speed.  Today, I flew one way rich of peak by about 100-150 and about 24" and 2500rpm (so higher power) burning 12.8 mph at 2500' and the other way 24" 2300 RPM burning 8.8 at 1500'.   The airplane flew much more smoothly with the lower RPM, but my IAS was about 30 MPH slower.

 

Thanks for the input y'all. 

[MB65E]

I installed a G1 drop in replacement for mine. I’ve also installed their drop in G2 replacement in other aircraft.
The older LCD units will drop bars individually when they fail.
Your issue does sound like a probe issue. They have tiny screws that could develop corrosion on the attachment leads of the probes.
-Matt 

[Pinecone]

Once LOP your power is directly related to the fuel flow.

Going 100 LOP WILL hurt your speed.  20 - 25 LOP will get you the benefits of LOP but without so much loss of speed.

[Fly Boomer]

10 hours ago, Kerrville said:

lean of peak, say 50-100 degrees, ..., CHTs seem a bit higher

I don't see how you could be 100 LOP with higher CHT.  Even 50 LOP will likely result in CHT lower than anything you normally see ROP.  At 100 LOP, your CHTs should be WAY lower than any ROP CHT you have ever seen.

[Guest]

I have seen the curve, but I also witnessed the chts on the gauge. It is an old gauge, perhaps it is wrong, or perhaps the lesser airflow results in less ram air cooling. I also saw slightly higher oil temps.