chasing wires
 

Bottom line: engine noise is coming through my speakers (weakly) with my head unit on. problem does not exist with head unit off (faceplate removed).
i hear it through the tweeters. same problem exists when speaker/tweeter component is wired to the head unit, and when they're wired to the amp.
there also seems to be a weak weak buzz when headlights come on. :confused:

any ideas/suggestions/experience would be helpful :D

check all grounds are good.

this sounds crazy but wrapping wires in tin foil is the "insulation" that more expensive wiring comes with and will prevent magnetic resonance distortion.

I'm not sure exactly what engine noise is but from an EE perspective it's probably on of those.

If they didn't do it when the speakers were connected to the deck then I would make sure your rca's are okay, or at least not running down the same side as your power wire. Also check your grounds.

Check your amp's ground AS WELL AS your head units ground (alot of people overlook this, but 25% of the time it is the problem) and check to make sure your rca connections are tight (on the amp as well as connected to the head unit). Also, wrapping wires in tin foil would probably just induce more noise...

Also, if your grounds are ok then you can run your power wire, speaker wires, rca wires, all intertwined with eachother and have 0 noise.