Erratic EGT

[Jim P]

I?m trying to diagnose an EGT problem I encountered today. At 9500 I was doing some leaning to re-balance my injector restrictors (Aero Sport XP-360, injected, c/s), and noted that the #4 EGT became really erratic, bouncing between about a 50 degree range (equipped with GRT EIS 4000), then progressing to a wider bouncing of a couple hundred degrees. This progressed for some time and eventually was bouncing between about 400 and 800. On the ground it seemed to settle down a bit but during the time, CHT was normal with no indication of a dying cylinder and mag checks were fine on the ground (I didn?t check in-flight). The temp flux on #4 was actually very fast up and down with no engine roughness or other indications.

I?m thinking this is either a probe or ground issue with that probe, but wondered if there were other avenues to investigate. I'll try and swap the probes around to see if the issue moves as a first step.

[SmilingJack]

I had a similar issue and found the connectors that are about 8 inches from the prob we very slightly loose.

I disconnected it, put a little liquid solder on it, crimped gently and no more issue.

Good luck!

[Jim P]

Thanks John, I'll make sure to check those.

jim

[RONSIM]

Wild swings to 2000+ and back, even ordered new probe -- but, checked crimps and found a couple of bad ones --- recrimped and solved my problem.

[Jim P]

Pulled the probe and it was pretty much toast. Need a call to GRT to get a new probe.

[Bob Axsom]

I'm sure you are concerned about the cause of the designed for the task probe being "toast".

Bob Axsom

[Jim P]

After some searching, it appears that some of the cheaper probes can fail with 250 - 300 hrs. With CHTs stable and normal, and previous EGT on that CYL not excessive, it does look like a bad probe.

[nucleus]

A poor crimp did this on my plane.

I also have an issue with the CHT's alarming for drop rate when I transmit on one of my radios, so I need to sort that out.

Hans