I just bought a 99 honda civic si with 50k, it has a b18c stamping on the block wether it is a b18c sir-g or (which i don't think it is because it doesn't have a red valve cover) b18c spec r, and running a p2t (stock si) computer. After it warms up a little is when the problem starts. rev it up to about 1500 rpms and it surges up and down between 1500 and 2500 rpm(idles fine). now the check engine light is on. i got a snap on scanner and it says it has a knock sensor fault. ok look for a knock sensor on the block can't find it.does a b18c have one and could this cause the surging. Please repond. i am inclined person w/ most tools and alot of automotive knowledge so understanding things is not a problem. new to hondas so please help and point me in the right direction.