If ignition timing is being intermittently retarded, say for example from an advance problem on a mechanical or vacuum distributor, or from abnormal noise in a knock sensor wiring harness on an electronic ignition vehicle (and the retardation is also evident w/a timing light at the flywheel), will shortened burn times be evident on the scope?

If a Dynamic or Running Compression Test is abnormal - restriction in air flow, a flat camshaft lobe, collapsed lifter, etc. - will that be corroborated by an abnormal secondary (or primary) pattern on the scope? What would you look for, in particular?

Thank you,
Mark