engine noise, electrical interference

This is a 2003 mazda protege 5, It has really bad engine noise when the car is running, interference when the engine isnt. If the engine is off and you open the door you get a really loud buzzing from the dome light being on. The setup, Pioneer 9800BT, remote grounded Pioneer Ipod adapter Pioneer Xm units Kicker 5 channel amp 4 gauge wire kit Eclipse 6x8 speakers all round Kicker CVR10 sub all power/grounds run down drivers side of the car all signal/speaker wires run down passenger side of car what I have tried, changing amps ground ground amp to battery to avoid the chassis run power and ground for amp to battery outside of the car to avoid interference changed head units, changed RCA's and RCAs routing used just an Ipod linked to the inputs on the amp from outside the car. regrounded the engine itself. changed amp. The only thing I can possibly think might be causing it, is noise being introduced in the wires going between the amp and the speakers as they are all run together down passenger side of the car. I havent had a chance to check that yet either. Would there be interference on the speakers if there wasnt any power on the speaker wires, because if the amp has no input signal on the RCAs or the RCA's arent connected there is no interference.

Hey first run a 12gauge wire from the battery to your headunit. Do not take the main power from the factory stereo wiring harness. Only use the factory harness to get your acc wire. Then ground the headunit to a known good ground. I have seen running a power wire to the batt for the headunit fix noise problems many times. In some cars like hondas using factory wiring for power gets you noise. Also try and locate the source of the problem if what i told you doesnt work. If you have a verified good ground to your amp that you have checked with the resistance mode on your dmm then it prob is not your amp that is causing the noise. I would concentrate on the headunit wiring.

hold on how are you connecting the ipod to get the sound into the amp and is it plugged in to any power?Also where is the amp mounted and to what kind of surface?Where did you mount the amp? Also I was gonna tell you to compare your ground with a known good ground using the resistance mode on your dmm but I guess if you already tried grounding to the batt hte there is no point.this has to be either a bad ground, rca to close to a factory wiring harness so its picking up the doelight or maybe the amp itself is in a bad location. I dont know what elsealso is the sound coming from all your speakers if not then maybe your wires are pinched

amp is mounted in the hatch area ontop of a fiberglass box. it comes from all speakers, I've ran RCA's through the middle of the car (draped over seats) and outside the car, and no difference is heard. I wanted to hook up a head unit without used the factory electricals but couldnt, so I connected an ipod using a stereo jack to RCA conversion cable, the Ipod was running off its own battery.I'm thinking it has to be a problem with the car itself. system worked fine for two and a half months and then suddenly started the interferance. you can hear it over the music when its at full volume, and its just as loud with no music playing.

It's not a prob with the car itself cause keep in mind you are only connecting to the battery not anything else. Also if you say it worked fine for a few months than there was no reason to change your ground, go back to your original ground. There was also no reason to move your rca's around, put them back to the location they were in when the system sounded fine. Now there are two options left. Possibly something happened to your speaker wires, check to see if they got pinched in the doorjamb where they go from the car into the door. Being that this system worked fine for some time makes it seem likely that your amp is broken. Things do break sometimesActually I doubt its the speaker wires but check that anyhow, probably just a messed up amp. Try putting an amp in place of the old one and I bet the noise will be gone

I really don't know what to tell you but just try and remember if there was anything that happened to the car when the prob started. You deff have hope if at one point this setup worked

i think if there was something wrong with the electrical system you would have other problems as well. Also is the amp touching any metal?Is the power wire possible rubbed out at a spot and making contact with the frame of the car?