I just hooked 2 sony explode 6x9's in my 1990 SE. At first they were hooked up to my HU and worked fine but I wanted a little better sound so I wired them to my Kicker IX406 amp. Now that i have done that I now have a whining noise that comes through those 2 speakers only when the engine is on. What can I do to fix this?

 

get a better ground on your kicker amp. if there's any paint at the grounding point, sand it off to bare metal, then resecure the ground. most noises in a system are caused by a bad ground somewhere.