compression is only 55!

Did a compression test today cause my engine light is on and the obd2 reader says its misfiring in the 4th cylinder. All the others were reading around the same but this one. Any ideas? Already have the valve cover off to check those.

 

Has it gotten hot recently ? If so, checked for water in the oil? If none apply I'm thinking valve/valve seat saying adios, not leaning towards a head gasket (cause that would probably involve 2 cylinders comp. being low) no knocking so a hole in the piston is out,maybe cracked head in combustion chamber ??

could be alot of shit

why valve cover off ?? checking cam for flat spot ? (which if it was both valves would be closed)

 

It depends on where the compression is going. Make a leakdown tester(if you have access to an air compressor). You will be able to tell what the problem is without a teardown.

 

I have it off to check to make sure I don't have any stuck valves.

 

Good call.
The leakdown tester will show where the leak is. Air noise in exhaust, bad exhaust valve. Air noise in intake, bad intake valve. Air noise in oil fill, bad rings/cracked piston. Air noise in radiator, cracked cylinder/blown gasket.
It has it's limitations, but it will give you a solid indication of cylinder health. They say 20% leakage=bad motor, but i'd say it's more like 10% and time for rebuild.
Google homemade leakdown tester. It will consist of two gauges, a regulator, orfice, valve, one male and one female quick disconnect. You make the orifice by stuffing one tube with epoxy putty and drilling the orifice. I think it's an"F" drill bit, but I'm not sure.