in-cylinder pressure using WPS500X in vis-a-vis piston ring condition

using WPS500X for an in-cylinder pressure test, can it be determined if piston rings are bad (too much oil consumption) other than a low psi reading? i have a sample waveform taken from a 2011 GMCs Terrain 2.4L whose owner complain about excessive oil consumption. engine runs well except that for every 2K km, she would always add about a liter of oil.

2000km/litre is roughly 750miles per Pint not that huge if it is a high mileage engine but by modern standards I wouldn't be happy with it.

The oil control ring/rings don't really have much effect on sealing against compression but they are as the name implies the one that reduce oil consumption. On an unworn engine 95% or more of the sealing against compression pressure is done by the top compression ring. As the engine wears the second compression ring does more of the pressure sealing. But the job of the oil rings is just to scrape excess oil off before it swamps the compression rings
So based on that if the excess oil consumption is down only to worn oil control rings I would think the compression humps and induction troughs can still look perfect.

I would look at crank case pressure the PCV and if you can look at the inlet for oil leaking down past the valve stem oil seals. I would also check what oil grade is being used if it is running 5w/20 a 10w/30 or 10w/40 might ease the problem.

I think you'd need to couple your in-cylinder transducer with a pressure pulse tester in the crankcase to really see a ring sealing issue. Or, use the pressure pulse tester with an ignition sync to pick out individual pulses.

...2011 GMCs Terrain 2.4L whose owner complain about excessive oil consumption. engine runs well except that for every 2K km, she would always add about a liter of oil.

Underlined the problem. :lol: These engines drink oil like it's their job. Sometimes you can help the situation by pulling the intake and cleaning the PCV orifice between the #2 and #3 intake runner, but usually it's a oil control ring problem.

At least your customer is checking their oil level! Most owners I've seen just let it go 'till the chains skip. :silly: