I was dealing with the same problems, and come to find out it was a tension rode to my timing belt.So I got a new timing belt and water pump, and tension rods and it stopped pinging..Now the only time I hear even a little ticking is when I forget to change the oil after 8000 miles:( ooops... hope you can figure it out, I said the same thing about my Z when my hicas broke on monday but deep inside I can't let go of the Z...