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Zig zag EGT reading

Tankerpilot75

Well Known Member
Flew today and noticed two interesting phenomena. First my #3 EGT reading (GRT EIS) was showing a zig zag line on the EFIS engine page read out. Second, my headset had a definite clicking sound coming through the intercom system that seemed to track engine speed.

Any suggestions out there where to look?
 
Flew today and noticed two interesting phenomena. First my #3 EGT reading (GRT EIS) was showing a zig zag line on the EFIS engine page read out. Second, my headset had a definite clicking sound coming through the intercom system that seemed to track engine speed.

Any suggestions out there where to look?

Have you ever changed out your EGT probes? Erratic readings could be indication they are at end of life and need replacing.
 
Flew today and noticed two interesting phenomena. First my #3 EGT reading (GRT EIS) was showing a zig zag line on the EFIS engine page read out. Second, my headset had a definite clicking sound coming through the intercom system that seemed to track engine speed.

Any suggestions out there where to look?

Sorry, don't know about the "zig zag" line, but a few weeks ago I was having erratic readings on my Dynon Skyview system for EGT and CHT.. I unplugged, cleaned and reattached the connectors and all readings are rock solid now..
 
Sorry, don't know about the "zig zag" line, but a few weeks ago I was having erratic readings on my Dynon Skyview system for EGT and CHT.. I unplugged, cleaned and reattached the connectors and all readings are rock solid now..

Yes, the erratic readings are usually from bad crimps on the spade connectors, not the probes themselves. There's lots of vibration in the engine compartment that can loosen the connections. Give a tug on the wires going into each connector to make sure they are tight. Also, bundle all of the wires tightly together with lacing cord. Individual wires & connectors don't do well by themselves.
 
given the coincidence with noise in the headset, I would be looking for an issue with grounding or something throwing noise on the power bus or ground. EGT sensor use a VERY low current and can't introduce noise into the electrical system. Noise that follows RPM should start with alternator and ignition, as well as engine to airframe ground.

erratic EGT indications is far more likely to be effect than cause

Do you have a PP alternator?

Larry
 
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headset clicking/crackling

I got this sound in the headset a while back, and it was a bad spark plug cable. How much of a zig-zag are you seeing on the EGT?
 
The zig zag is constant with #3 EGT only. The headset clicking is also constant but volume adjustable using the volume control on the Garmin 340 intercom - not affected by radio volume.

Like rv8ch said, I’m leaning towards a bad plug on that cylinder. I’ve got a couple of spares so I might just swap #3 plugs out to see if it makes a change.

I have noticed that my aircraft ground is a little suspect since the engine starter can be a little difficult to engage and I installed a new EarthX battery last fall. Once the starter engages it really spins so I’m thinking the ground is a little suspect.

The alternator is plane power.
 
I too have the problem with erratic EGT readings on two cylinders. how to clean the spade connectors? did you re-crimp the connectors?
 
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