I have a 97 civic dx and just recently did a valve adjustment on it...about a week later had to smog so took off dc headers and put stock ones back on than after smog put dc;s back on. Check engine light flashed...thought it was just an 02 not connected properly....Tried reattaching to no prevail . Than a day later the engine after 3k rpm's does a nasty ticking sound. Sounded as though it was from the head but could be wrong. i than rechecked valve lash on all cylinders and was ok....please help any suggestions comments would be helpful. let me know if anymore info is needed.....