well addressedWell Jdog, more information on your car and system would help me help you. Im going to take a wild guess here though and say you have system noise. This is likely from bad ground, a ground loop, or RCA's being ran parallel to a noisy power wire. Does it do it without the RCAs hooked up? What type of amp is this? What type of speaker? Is it a sub? How is it wired? How are the wires ran and hooked up?