EGT dance

[The-sky-captain]

Today on my flight back from the in -laws I noticed my #4 EGT varying from 1285-1320 like clock work. As soon as it hit 1285 it would reverse trend and climb up to 1320 and vice versa. #4 is always the coolest of the four but this is the first time I have ever isolated it on the JPI and watched it for any length of time, which was about 5 minutes. All CHT's were normal as were the other  EGT's. Any ideas to the cause?

On another note it was a great couple days for flying in my neck of the woods. Hope everyone had a great holiday.

[MikeinFL]

Might be time for a new EGT probe.