injector pintle doesn't fully seat on orifice

CAUSE OF FAILURE 5...fuel additives "baked" on pintle or orifice, weak injector return spring, rust/corrosion internal to injector body.

EFFECT OF FAILURE 5...leaking fuel injector, after shutdown fuel leak in affected cylinder (causing hard start), overfueling of affected cylinder with resultant underfueling of remaining cylinders in the "closed loop" system, potential for damage to O2 sensor or "cats".