I have a easy one i bet - but it has stumped me for a year .
I have a 99 civic Si - I have transfered a system from one car to another 3 times without problems. BUT
on this last one I have run into a problem - a big pain in the but one...
- - - - - Alternator wine. you know the that one..
first off - does hondas have a different electrical system ? I had a 95 dodge charger and the speakers where 12ohms run in parrellel so when i replaced them - well never mind It wasnt fun... I had a kenwood head unit / Orion HCCA amp and JL Audio subs and Boston Acustics speakers w/ stinger all around... full over kill.
NOW here is my system a
- Kenwood Head unit CD/MP3 player , going to a
- Rockford punch 900 running 5.5 Bostons , 6x9 Sony Explode = from the 900 there is a RCA output (base), going to a Rockford punch 600 bridged running
- 1 JL Audio W0 in a sealed box.
extra equipment =
- .5f stinger cap , zero noise street wires RCA's , Street wire speaker and power ground , all the fusses and distrib blocks are stingers.

-I have replaced the head - both amps. thinking there going bad, It was a sad day when I tossed the HCCA - I loved that amp.
-I have upped the gauges on all grounds .
-I have run the RCAs dirrectly from head to amps.
-I have elimanated the CAP from use. then both the CAP and sub amp.
-I have added ground loop isolator on the power of the head.
-I have relocated the head units ground, also connected it dirrectly to the battery.
-I have run the power from the head dirrectly to the battery.
-I have relocated the main ground 4 times (from strut area - to wheel well - now it is bolted to a spot near the main frame support on the rear axle area - in the center = allpaint removed sanded - with lock washers and those washers with the toothed edges )
- I thought since the civic Si has a electric plug instead of the normal grommit going from the car through the gap to the door, that maybe the power leads or grounded wires going to the mirror and window = might be causeing it, but I allways thought noise can only enter before the amps... SO I was going to get a set of Q-forms but 190 bucs is alot..
- NOW I have been told there is a ground loop isolator for the RCA's , go figure..
thats news to me....
What do you think ?? will that work ? or was I being BS'ed

 

First thing i'd do is remove the ground from the battery and use the body as the ground (any grounds should go directly to the body). Also check to be sure your power wires and speaker wires are not run together.