EGT problems

[rogersmart]

I had observed my EGT temps on cylinder #1 and cylinder #2 having erratic behavior. Cold, All CHT's and #3,4 EGT showed consistent temps matching current ambient temperature such as 72 degrees. #1 EGT had an X and #2 had 50 degrees.

During warm up, #1 and #2 showed lower temps but eventually catch up and show temps similar to #3 and #4, within 20-40 degrees. After shutdown, the temps fall rapidly until #1 goes negative and then an X. #2 falls and levels out lower than #3 and #4

I ordered replacement EGT probes part # 100405-000 for #1 and #2 and installed them.

Cold both #1 and #2 now match exactly #3 and #4 at the ambient temp which yesterday was 65.
I then when for a short flight and #1 and #2 both showed temps 200 degrees greater than #3 and #4.

My first thought, being brand new they may have to heat up once or twice to send correct temps. I plan to fly some more and record better data but wanted to see what ideas were out there for this occurrence. My obvious concern is what are the real temps and which sensors are reading correctly.

Skyview 10”, Lycoming O-360 fixed pitch Catto 3 blade

 

[mmarien]

The differences in absolute temperatures occur from a number of reasons, one of which is the placement. If they are not equal distance from the flange they will measure different temperatures.

I think if you do the research you'll find that the absolute EGT are not as big a concern as the changes from the normalized state of the EGT's. Some EGT displays have a method the normalize them. You find a request for that function on this forum for SV.

http://dynonavionics.com/cgi-bin/yabb2/YaBB.pl?num=1343967193

As mentioned in the thread, Mike Busch has a number of articles about EGTs.