"Jim Burns" wrote in message
...
I'm studying the JPI data from my recent trip to Key West and back to
Wisconsin. One thing stands out.

A sudden drop of 60 degrees EGT and rise of 30 degrees CHT on one cylinder
while all other cylinders remain rock solid stable.

After an extended period of idling at KEYW waiting for a clearance and
then an amended clearance and then a second amended clearance (20+ min)
while aggressively leaned, we performed a second run up to check for
fouled plugs and everything was normal.

Looking at the JPI data for this leg of the flight shows the #1 cylinder
on the left engine reading the lowest EGT and lowest CHT for that engine
during runup, but during takeoff it jumped to the hottest EGT while
remaining the lowest EGT. It remained the hottest EGT for approximately 1
hour and 30 minutes of flight at which point it dropped 60 degrees EGT and
gained 30 degrees CHT. This brought the EGT for #1 back into it's
"normal" position as 2nd coolest between #3 and #6, where it had been on
most previous and subsequent flights.

Since this "event" I flew 6+ more hours back to Wisconsin and another 2
hours yesterday shooting approaches. No abnormalities noted.

I can understand a sticky intake valve causing a high EGT then a drop to
normal levels if the valve returns to normal operation, but what's with
the rise in CHT?

Curious.
Jim

How about an intermittent leak on the induction tube on that cylinder? I
could see a slightly lean mixture resulting in the behavior you noted.