Morning sickness on an engine monitor?

[Tokirbymd]

Lycomings have a tendency for valve sticking this advocated to do the wobble test every 400h or so and to be on the lookout for “morning sickness”, or rough running after startup that evens out when the engine warms. On a 4 cylinder this is noticeable but on a 6 cylinder less so. Would the EGT on an engine monitor show anything that would indicate this? I would think with a valve sticking that EGT would indicate low on that cylinder until it warmed? (Thinking that it would likely stick closed).

 

[Salty]

Lycomings have a tendency for valve sticking this advocated to do the wobble test every 400h or so and to be on the lookout for “morning sickness”, or rough running after startup that evens out when the engine warms. On a 4 cylinder this is noticeable but on a 6 cylinder less so. Would the EGT on an engine monitor show anything that would indicate this? I would think with a valve sticking that EGT would indicate low on that cylinder until it warmed? (Thinking that it would likely stick closed).

I don’t think it would be physically possible to stick closed unless more than one thing was very broken and making really bad noises.

 

[MooneyDriver78]

Something like this:

 

[Salty]

I don’t think it would be physically possible to stick open unless more than one thing was very broken and making really bad noises.

I meant closed. Edited the original.

 

[Hang 4]

I believe "morning sickness" is valve open which equals 0 compression. As @Salty said, if it was stuck closed, bad noises would happen. Low EGT would be my best guess at what you'd see on a monitor like the purple line on the post above.

 

[MooneyDriver78]

It’s exhaust valves sticking open, so no compression.
The mixture still ignites so EGT drops but not to outside temperature.
The motor will shake a bit at low horsepower, here’s an example of it occurring when I pulled power to descend for landing:

 

[Tokirbymd]

Thanks. I guess I meant sticking open as sticking closed would result in bent pushrods. That is the graph I was looking for. Now to differentiate it from my #5 EGT probe going bad.