my question is. i bought the i injector new, came with two o-rings on it. one larger upper, one smaller lower(before the pintle cap) , i then bought a seperate o-ring kit. it came with the rubber insulator for the outside cap. the two o-rings i had and a large rubber insulator? what is the large rubber insulator used for? when i removed the factory injector i saw no rubber insulator like this.