When i first installed my head unit i had factory speakers but i had an amp hooked up to a sub it was fine.
but now i hava a second amp hooked up power the speakers for the door and rear and i hear a noise in the front not sure if its in the the front speakers or the head unit or even somewhere in the dash its just in that area. but it only does this in drive and the car in moveing but if i rev the engine in park it does not do it. when the head unit is off it completly stops.

 

Its called ground noise. Make sure you have both your amps grounded in the same location with a nice clean spot. THen look at your RCA's and make sure there not split, cut or near the power wire.

 

my system is not curretly hooked up because i am doing some mods to my system, but when i haave the RCA that i use for the amp for the front and rear speakers is connected to the HU it stills make that noise and the power wire is not connected so its not that is interfearing. but on the wireing harnness that i used when i plug those RCA in so the sound would come through the factory amp it does not do that noise. but when it does its still only in Drive not park

 

Thank you! Somebody that got the first step right.

Double check those grounds and make sure they are clean. Do a professional job on them and not some "good enough for me" or "I guess that will work" job. I hate seeing people drop 4 grand into a stereo and then look disappointed when it sounds bad.

 

I have done the above. I already new all those steps. It is all grounded to the same spots clean and the RCA are on the opposite side of the vehicle so there is no interfearence. Everything was in clean. I am going to take the dash off once and see if there is something back there.