I have noticed my turboed Z6 (original 169,000 miles) has been having a little ruff idle lately and sloppy starting, so I did a compression test and am a little confused.
170, 140, 160, 180. So cylinder 3 is low...could it be a ruff exhaust lobe on my cam(hence the idle?) I put oil in that cylinder and compreesion rose up significanly. Car drives fine, does not burn oil and my over flow is always at the same level. Also why might my center cylinders be lower than the outwers?

 

Sounds like rings to me homie.

 

If your compression goes up after adding oil to the cylinder it usually means the rings are failing.

 

I just did a comp. test on my DNinja and got # 1.190 #2.195 #3.210 #4.190. Sounds like something else man. Are you positive you had a good tester ?

 

ya brand new tester. Manual says that normal is 184, with lowest being 156. I guess I should start saving to build up my spare block huh.