My car is a 1992 honda accord and I have a 15" kicker L7 connected to a power acoustik sapphire sp2x 1600w well I've hooked it up before and it was great and loud just like i wanted it to be except i had to disconnect it because of some trouble with the car itself and that was about last year I have just had the time to be able to put it back in but now the speaker whether the car is on or not (amps on though) thumps like a heart beat i shut off the amp and of course nothing comes out I've tried just about everything that I can think of someone help me I want my bass back!!
Try twisting your RCAs and see if the connection gets better. Sometimes the RCAs dont make a good connection, just like a weak ground.
Check all (I mean all of your wires) for cracks, splits, bare wire, kinks, anything that may cause a short, or a disruption in your circuitry. Use your eyes and hands first. Dont just use a continuity tester.
Also check for inteference between power wires, RCA cables, speaker wires etc... Make sure these wires/cables are not near each other. They may cause inteference, and you may get some extra unwanted noise.
I would even check and make sure that there are no other electrical/electronic items running on the same circuit as your Audio system. Sometimes people try to hook up other things to share power and/or other networks. This may also cause extra unwanted noise.
Also check your alternator to see if it is working properly. Your local auto parts will check it for free.