I was checking my spark plugs because my car has been bogging pretty bad below 4000 rpms, and when I pulled the #3 plug, smoke came out. Any ideas what would cause that. All the other plugs were fine.

 

smoke or steam?
if its steam chances are water is getting into the cylinder which means blown gasket.

 

I assume it was smoke, but I really don't know. I will do a compression test to see about the head gasket. But what does it mean if it is smoke?

 

maybe some oil leaked into the spark plug hole from the gasket between the valve cover and the head and started burning off. If there was enough leakage from the head gasket to make steam you would notice other problems like smoke from your tail pipe

 

burning oil maybe? damn that #3 honda cylinder.

 

If the car was bogging bad, it may be excess fuel venting in a fog. Look for bad plug, wire, leaking injector or compression problem in that cylinder.

 

Thanks guys I am going to try and do a compression test this weekend.