In-cylinder, cranking, low compression waveform looks like a leaking exhaust valve, but it isn't
The vehicle is an 06 Ford Escape 3.0 cranking, no start, no codes.
In the first capture, the red Channel B is a "First Look Sensor" pressure transducer, on the dipstick tube, to compare each cylinder's "blow by" pressures past the piston rings into the crankcase.
The green CH C is the relative compression and the higher crankcase pressure, in CH B for cylinder 2, lines up under the low starter amp draw for cylinder 2.
The tan CH D is a WPS500 pressure transducer in cylinder 2 and the compression is measured at 78 psi. The compression/expansion stroke tower is leaning to the right and the vacuum pocket at the bottom of the expansion stroke measures at 9.9 psi or near 20 "vac. Looks like a leaking exhaust valve.
In the second capture, CH C is the relative compression amps.
CH D is the WPS500 on the dipstick tube and the high crankcase pressures line up under the low starter amps. An old COP spark plug boot works well to connect the WPS500 to the dipstick tube.
In the third capture, CH C is the relative compression amps.
In CH D, I put some oil into cylinder 2 and now the cranking compression measures near 200 psi.
In the fourth capture, CH C is the relative compression amps.
The blue CH A is the injector 2 voltage on times. The maximum cold cranking injector on time is near 20 ms.
A used PCM was the fix and the engine now runs well.