Just noticed this thread when I did a search and need a bit of advice, my car runs O.K but Ive just changed the oil and noticed that the black plastic sleeve that insulates the wire from the knock sensor is broken open in several places but the car runs fine ! Should I change it, cover the damage with insulation tape or just leave it alone ? I'm a bit unsure about changing it as I'm quite good at f*cking up delicate jobs like this . Any advice or suggestions much appreciated