subwoofer makes the same sound as car idle but when i turn up the volume it gos away i think its my ground but idk

 

Did you run the wiring, or did a shop? Likely cause is your power wire crosses with your RCAs at some point. Its always best to run these on opposite sides of the car, Power/Remote on one side, RCA on the opposite.

 

its the magical power of the universe surging through your car.

we can't really tell you anything if you both give us no information, then don't ask any kind of question...

 

exactly what he said!

 

It's usually just cables being crossed just re-check ur wiring and u should be cool I had the same problem

 

Engine noise through speakers in most cases is either a bad ground, or your rca's are too close to your power wire. If you look at most amps, they have the rca outlets on opposite sides from the power & ground outlets.

 

Reiterating what everyone else said; ground loop or interference through RCA's.