I was hoping that maybe someone could help me with a little problem I just started having. Today, I started hearing this thumping sound that is accompanied by a very rough idle. It sounds like a valve or vales are getting stuck or misfiring in some fashion. It is also accompanied by a loss in power. Not a small loss but fairly significant. Has anyone experienced this problem before? Or does anyone know what's going on? Any feedback would be much appreciated.

 

The rough idle might be consistent with a burned or damaged valve. Start with a basic compression test, which could identify a 'low' cylinder, if in fact a valve is damaged.

 

Thanks. I'll check it out.