First thing about my car, battery is in the trunk.

Right now, I have grounds from the two amps plus capacitor to a ground block via 4 gauge, then a 6-7 foot run of 2 gauge to the main battery chassis ground. Then I have a short run of 2 gauge from the chassis ground to the battery PLUS the existing run of 8 gauge that was stock on the car. It's just a lot of freaking ground wires.

Replacing the 8 and short 2 gauge will be a short run of 1/0 to the battery. The 2 gauge run from the distro block will be played with. I'll try grounding it to the chassis near the amps first to try and cut down on the length.

i would try it
i do think it is the neg wire,have you tested the wires with a ohm tester?

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EVERY FAMILY HAS A RETARD IN IT. IF YOU THINK THAT YOURS DOESNT HAVE ONE, THEN ITS PROBABLY YOU.

No not yet. It's on the "to do list", which is unfortunately longer than the amount of free time I currently have I'm hoping to get a bit of it done this weekend while the fibreglass resin is setting up.

i know what that is like
it was a year befor i got to my wire and things

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EVERY FAMILY HAS A RETARD IN IT. IF YOU THINK THAT YOURS DOESNT HAVE ONE, THEN ITS PROBABLY YOU.

I didn't read the whole post it was too long but perhaps you can try a ground loop isolator

in sq why
fix it not hide it

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EVERY FAMILY HAS A RETARD IN IT. IF YOU THINK THAT YOURS DOESNT HAVE ONE, THEN ITS PROBABLY YOU.

would probably be easier if u drew a picture. but whine comes through when theres even millivolt difference in ground.

from what i got, you have each battery grounded to the chassis in multiple locations?

i dont know im just confused. a pic would really be helpful

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Pioneer DEX-P90rs + DEQ-P90rs (from europe)
Front Stage - Focal Utopia Be No.7 (active) Focal Utopia Be 13ws (x2)
Front Stage + More Bass - JL Audio 8w7 (x2)
For Beating Brains Out - JL Audio 12w7
Amps - JL Audio 300/4 (tweets/mids) JL Audio 450/4 (mid-bass/subwoofer) JL Audio 500/1 (8w7's) JL Audio 1000/1 (12w7)
250amp Alternator, Stinger SP1700 (battery)
All Monster Cable (lots of it)

try removing the cap
but i think it is the ground is bad

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EVERY FAMILY HAS A RETARD IN IT. IF YOU THINK THAT YOURS DOESNT HAVE ONE, THEN ITS PROBABLY YOU.

There is only one battery, and it's in the trunk. It's just how my car came from the factory. No room under the hood. It has a weird ground setup that I made weird. Working on that.

We've tried it with the cap out of the system to no avail. Not much I can do for now until we get the fibreglass thick enough to get out of the car, so wiring is on hold for now

Thanks for the suggestions guys!

Little update:

Still fibreglassing, haven't had much time. However, after much searching and tinkering and talking to other E36 owners, it turns out that the power wire from the factory harness is run through the OBC (on board computer) and the digital temperature control unit, before it gets to the HU. The factory HU has a choke installed to take the extra distortion from the power line.

Several other guys have had success running a new power wire from the battery. If that doesn't work, I can put a choke on the power wire too and see if that helps.