Hello Nissan owners, If you have a S/C Frontier pickup truck and you here a KNOCKING noise from the engine. Your going to be replacing your s/c. I just bought this new 2003 Frontier truck, I have 3000 miles on the on it , and I hear this KNOCKING noise from the engine. It starts to make this desil engine noise from idle to about 1700 rpm. some times its loud and some times its faint to hear. Well I thought it still might be braking in so I drove it for another 1000 miles and still hear it . So I went to my dealer and they said its a KNOWN problem & their going to replace the S/C unit. Boy was I pissed.Has anyone had this problem.They say the rotors are not matched up to each other, and they bined under a load. Have fun with this big $$$$ item. I wish I could get rid of this truck. I'm stuck with it for 5 years.