I was driving my car in a normal way and all of a sudden i can hear this loud ass knocking noise in the engine. I pop the hood and it sounds like the pistons are knocking around the inside of the engine. I have a JDM B16 that I bought from Hmotorsonline.com just two weeks ago. This engine can't be messed up already, I haven't even gotten a chance to get on it. Someone tell me what this can be. Thanks.