Annoying Engine Noise

So I went to circuit city last night to pillage the last of the Goodies. I got a few good things
I managed to pick up a few things inlcuding the JVC KW-AVX710 Headunit for $50 bones! Good stuff! I also picked up the Circuit City Nissan Harness that worked beautifully except for the ground I had to run a separate ground. I also picked up the antenna adapter. I swung by home depot and picked up some solder and a new tip for my weller gun. I came home took apart the dash and took apart the system and pulled the factory radio. I wired up the new harness and was left with 1 free wire the dimmer ground? I don;t know what to hook that up to as I have wired the regular dimmer wire to orange illumination on the harness. Now I installed everything and turned on the car and no power to the radio. Fuck! I was pissed wondering if i got a defective unit. So i figured the damn thing needed 2 things to power up 12v power and ground. So I desoldered the connections for power and ground and ran 2 leads with aligator clips to my battery and walla it works. So I reconnected the 2 power wires to the harness and left the ground on the battery. Turned on the car and it powers up. YES MPHKR I AM SO HOOD!!!!!!!!!!! That led me to believe that the ground was not working so I took another piece of wire and crimped a ring lead to it and connected it to the harness ground and soldered the radio ground to those 2 effectively a negative double ground. The radio works yes! BUT!!!!! I have radio noise like i am riding around with R2D2 in my trunk. Little whines that go up in pitch as the engine speed picks up. So i figured I  have a bad ground some where maybe that is why the radio did not kick on earlier. So I went through the engine bay and grounds were solid. I checked all other grounds as well including the grounding strap for the transmission....No luck. So i figured I have a bad ground in the factory harness. So i desoldered all the ground connections ( I like solder). and ran a hard ground from radio to the chassis. Hory Shitto, it should work. NO SON OF #^)#*&%)^(*@)*%@$@#&4!!~.  I was pissed so I gave up an hoped some of you would be able to help me. I know about ground loops and possible weak wires but thiese are 18g shielded wires why so fubard? I don't want to use engine noise eliminators. Keep in mind the car has stock speakers and amp with aftermarket head unit......

im not so sure if this helps, but i know you have to bypass the factory amp. they make a specific harness for that, thats what the peeps at AF told me. so im assuming you cant just use a regular nissan harness. but someone with more knowledge should chime in. :shrug:

oh ok where is this amp bypass? and how much?

sorry i am late to the party here, what car is this in?
i can probably give you a diagram to bypass your stock amp. it will cost you nothing to wire it out of the equation.
 
also are your wires all taped together or something? how about checking the antennae adapter?

i need to check the antennae adapter but no my wires are soldered i solder everything... and heatshrink it. my car is 1997 Q45

find another location for your ground wire and or shorten the ground wire if its too long

you should have said something cause I didnt hear shit last night when I was in the Q

i tried everything save for rewiring the whole car.  the factory radio is back in the car

Stop soldering anything until you finish the tests.
I would order a new harness first.
You say you have a spare wire to dimmer ground.
Where is the wire on the harness or on the radio?
Did the last radio in the car work?