My friend's crx si has been running rough so I did a quick compression test. came out 180 180 180 0. The spark plug on the bad cylinder was fouled and covered in oil, the rest were clean. Coolant is clean. I'm guessing itd have to be a burnt valve to cause such a loss in compression... do you guys have any ideas what else it could be? tia

 

It's most likely a jacked up valve (bent/burnt). Obviously the only way to find out for sure is to pull of the head... Good Luck!

PS - keep in mind the D15B2 (Dx) heads are almost exactly the same as the Si head, except for the camshaft. Incase you decide to replace it....

 

I pulled the head. you were right, burnt exhause valve. thanks