wrote:

If its fouled.. it isn't burning all the fuel that is being injected
into the cylinder and thus your compression is actually forcing that
out the exhaust thus lowering compression because its not pushing the
cylinder all the way do BDC so your not getting the full potential out
of your cyliner or engine with the plugs are fouled.


Based on how I've seen a compression test performed, that makes no sense
at all. Either I'm using the wrong terms or I'm not understanding your
description.

AFAIK, Compression tests are performed with the valves closed and the
cylinder at full compression, where a reading is taken, and possibly
watched for leakage (a diminishing reading).

Are you an A&P?