All CHTs and EGTs jittery < 2400 RPM, fine above

wfcloring

New Member
Joined
Nov 13, 2020
Messages
5
In cruise in a BE35. The engine sensors' display values on my HDX jump around a lot (> 50 degrees) when the RPM is < 2400. Once I go above that, they settle down. It only just started 2 flights ago. I had all the connectors checked/tightened. Wondering what else I should look at.
 

MikeD

Member
Joined
May 14, 2023
Messages
68
In cruise in a BE35. The engine sensors' display values on my HDX jump around a lot (> 50 degrees) when the RPM is < 2400. Once I go above that, they settle down. It only just started 2 flights ago. I had all the connectors checked/tightened. Wondering what else I should look at.
Need more specifics. I would start by downloading the EMS data log. You can then review the Excel file for correlations and anomalies. You can also upload it to Savvy Aviation to graph and analyze various sensor readings.

You mentioned that the problem just started showing up. Depending on how frequently you fly you may be able to see the cut over date as to when the problem surfaced. The before and after views of the EMS data might help identify the cause.
 

V-tail

New Member
Joined
Jan 4, 2025
Messages
4
I have a similar situation. After initial install - RPM was stable. Now, at startup and trying to set idle around 1,000 RPM, the RPM indication is erratic. The engine RPM itself is stable - no large fluctuations - just the RPM sensing which is at the MAG/Ignition switch. It occurs on only one MAG setting and therefore also on both. If I increase RPM over 2,000, then the indication stabilizes. My A/P added resistors at the ignition switch but the result remains erratic. My A/P indicates this is a common method of connecting for RPM sensing to the Garmin approach. However, he does not see Garmin solutions having similar erratic readings. This is also in a BE35.
 
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