1998 w202.029 m112 c280
On the back of each of my coil packs, there is an exposed strip of aluminum, which outlines 1/4 of the upper pack, runs through the center/middle of the upper and lower portions, to encircle 1/4 of the lower portion. Does this act as a ground, needing a clean connection to the valve cover? Does that strip need to be clean, or can the crud there be left alone?