If your engine is pinging or knocking...
 

Before you worry about it, before you post about it...

CHECK YOUR OIL LEVEL, IT MAY BE LOW!!!
This may be your only problem.

Our cars can leak alot, and your oil level can get pretty low seemingly quick without regular attention to the dipstick. Besides endangering your engine and other components, a low oil level can cause knocking and other disconcerting sounds.
Just a suggestion born of recent experience;)

True enough - oil change always brings improved performance too. Otherwise I'm thinkin that any diesel driver who doesnt go under the hood and check fluids at every fill-up is missing the full experience.

Yesterday I noticed the dipstick varies in its measurement depending on which side of the dipstick is checked..... engine side reads higher than the outward side.