audio interference

[lfdsteve]

Installing stereo in my 71 firebird resto mod. I have pioneer head, alpine front and rears, 2 10 inch Kenwood subs mounted in trunk with 2 JVC amps and a cap to drive the whole system. battery is trunk mount. All electrical runs directly to battery side posts with exception of head unit which uses original dash wires. All vehicle functions run off separate top posts on battery.
So my problem. It works great when car is off in acc position. It also works great when car is In run position but engine off. This includes fuel pumps fans ect running but not engine. But if engine is running I get a loud pop sporadically thru the system, sounds like when you used to listen to a record album and there was dust on the surface.
Engine is 462 pont with powerjection EFI, coil on cap distributor Acell shielded plug wires.
I am assuming ignition related but its sporadic.
Any thoughts at all?
Thanks
Steve

[Modo Innovations]

Most of the time your issue is caused by a poor ground. You stated that your head unit uses the factory harness, I would ground it to bare metal close to the unit instead of using the factory harness ground. Also look at your RCA cables, are they routed close to any power wires for your ignition control box? This can cause interference issues as well. I hope this helps. There is nothing worse than having noise in a nice stereo system, it's such a bummer.

[hessdawg]

Also make sure your alternator has atleast an 8ga ground
As well as the battery ground to the body and the chassis

[raustinss]

I got to agree with both previous posts the vast majority of electronic issues are related to the ground, check all grounds, engine to body.engine to frame.body to frame..radio to body and yes rca wires are notorious for picking up ignition noise when I was big into stereos (90's)lol everyone ran the rca's down one side of the car and power wires for the amps down the others. Try to shield the ignition system. Another thing to try unplug the rca wires from the amp then turn on the stereo without it. If you need to use a jumper wire for the speakers then do that. This should help you figure out if the noise is coming from the deck or thru the amps
Good luck
Ryan Austin

[lfdsteve]

Tnx for the info. Ill start checking the grounds first