Weird coil packs I've never seen before?

[echonightsi]

So I replaced a coilpack on my N/A 300zx to see if it fixes the low rpm and smell, and the new / used one I received had a cover of unknown material over the spring inside the coil pack. Can someone explain to me what this is and if it is supposed to be there ?

original



new/ used

[centralcoaster33]

All I see is a different style of contact. If it conducts electricity, it probably stays, if not, I guess it could be a cap, but I would expect a cap to have access to remove it, like a handle or something to tug on.

[echonightsi]

Why would there be a cap on something that is hard to damage , or at least reach. As replacing it got me no where I have yet to discover it it actually worked or if that cap is not supposed to be there.