[fliprayzin240sx]

If you have an SR, just unplug your CAS. Plug the tester in, crank the engine upto 5 revolution. Watch the needle jump 5 times. Per FSM, 125 is lowest acceptable number. I'd shoot for atleast 140. Also, all 4 cylinder should be within 20 psi of each other. So if you got something like 140, 150, 155, 160. Thats still healthy. If you get something like 120, and then everything else is roughly 150, then you have a dying cylinder.

Drop a cap full of oil and see if the compression jumps higher on that cylinder. 120 and then it jumps to 140, then thats a sign you have a leaking piston ring.