LOP Mag Check -- What does it mean when ...

My notes from the Advanced Pilot seminar show the following interpretations of the engine monitor's EGT readings during an inflight mag check (or otherwise):

1. EGT continues to rise: plug failure
2. EGT falls (if LOP): fuel injector blocked
3. EGT rises (if ROP): fuel injector blocked
4. EGT soars: valve failure

I follow APS's advice every flight and do a high power mag check while running LOP. It takes less than 20 seconds. On the ground I just switch to each mag while taxiing, just to ensure that there is no gross failure.

I also do a quick GAMI spread test every 50 hours, after every maintenance visit. It takes less than a minute. I'm looking to see that the fuel flow between the first and last cylinders to peak is less than 0.5 gph: this means that all six cylinders will function in close unison so that I can run LOP without concern that some cylinders might be in the red box and will run too hot.

For more insight on the how's and why's of all this engine stuff, I would highly recommend to every serious Cirrus pilot that they attend the APS seminar.