Engine noise help

[bubbaccb]

Hey guys, I’ve been running into a problem with my system that I can’t seem to figure out. I have intermittent engine noise at totally random times. I had originally thought I fixed the issue when I remade my radio harness with a noise filter and isolated everything with relays including the acc and amp turn on. I then ran a ground to the same location I grounded my two channel at on the body of the car. And that also wasn’t the fix. I am getting noise through all of my amps (2 channel for tweets, 4 channel for mid bass and mids) and presumably sub channel if any of the frequencies in the noise are low enough. I can also rule out the head unit because my previous one (80prs) did the same thing and I would doubt my p99rs is the issue either. I also highly doubt it’s from any fields getting into the rca’s because when I unplug them from the back of the head unit the noise is gone. Could I need a ground running from the 4 channel point to the 2 channel point? I’m running out of ideas on this one. And currently I also have a quieter hum when the ignition is on but dead silent when only Acc is on