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  #1  
Old 04-01-2021, 04:34 PM
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Tankerpilot75 Tankerpilot75 is offline
 
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Location: Oklahoma City, OK
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Default Zig zag EGT reading

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?
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Superior XPIO-360, Hartzel CS prop, Dual GRT Horizon WS, EIS, Garmin 340, 335 w/WAAS gps, Dual 430s (non-WAAS), TruTrak 385 A/P with auto-level & auto-trim, Tosten 6 button Military Grips, FlightBox wired to WS, Dynon D10A w/battery backup, 406 MHz ELT. Custom Interior, New TS Flightline hoses, Great POH!
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  #2  
Old 04-01-2021, 07:57 PM
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RVbySDI RVbySDI is offline
 
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Location: Tuttle, Oklahoma
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Quote:
Originally Posted by Tankerpilot75 View Post
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.
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  #3  
Old 04-01-2021, 08:34 PM
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jrock836 jrock836 is offline
 
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Location: Burleson, Texas
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Quote:
Originally Posted by Tankerpilot75 View Post
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..
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  #4  
Old 04-02-2021, 12:15 PM
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rswalden rswalden is offline
 
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Quote:
Originally Posted by jrock836 View Post
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.
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  #5  
Old 04-03-2021, 10:11 AM
lr172 lr172 is offline
 
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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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Last edited by lr172 : 04-03-2021 at 10:16 AM.
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  #6  
Old 04-03-2021, 11:53 AM
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Default 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?
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  #7  
Old 04-03-2021, 08:14 PM
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Tankerpilot75 Tankerpilot75 is offline
 
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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, Iím leaning towards a bad plug on that cylinder. Iíve 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 Iím thinking the ground is a little suspect.

The alternator is plane power.
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Jim Harris, ATP, T38, EC/KC-135A/E/R, 2008 RV7A, 2nd owner, N523RM (2015)
Superior XPIO-360, Hartzel CS prop, Dual GRT Horizon WS, EIS, Garmin 340, 335 w/WAAS gps, Dual 430s (non-WAAS), TruTrak 385 A/P with auto-level & auto-trim, Tosten 6 button Military Grips, FlightBox wired to WS, Dynon D10A w/battery backup, 406 MHz ELT. Custom Interior, New TS Flightline hoses, Great POH!
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  #8  
Old 04-04-2021, 06:44 AM
KayS KayS is offline
 
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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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