Audio interference consistant with RPMs

[Devin]

So I have an odd problem. I have an aftermarket Premier DEH440 with the standard black box and gray rectange ends to my JBL system. After I first installed it, I noticed that there was no negative wire pin for the front rear speaker. However, the front rear speaker still worked. However I had this scratching sound that would come and go as I would drive over bumps. That went away and now I have a whine that corresponds with engine RPM. The sound stays the same no matter what volume I turn up (so I can drown it out mostly) but when I am moving it can get pretty high pitched.

The two things I was thinking it could be are the little interference module coming off of the coil pack, or a ground issue. Any ideas? I double checked my butt end splices on the adapters, the connection to the speaker in the door, and the amp connections, and all seem to be tight.

 

[LJRuddy]

Id try a new interference module first... They are dirt cheap and if it does not work, you can always take it back for a refund.

 

[Devin]

Are they aftermarket or do I have to get a dealer one? This is a 90, by the way.

 

[LJRuddy]

I'm not exactly sure exactly what its called but just pull it off of the car and take it to a parts store and tell them what kind of cars its off of. They are probably pretty generic and Im willing to get Ford used the same exact one on 99% of the cars they made during 1990.

 

[Devin]

Got it, thanks.

 

[Toul]

Youre problem is interference from your alternator, most comonly caused by power wires too close to signal wires. Without knowing more about your system though its hard to say exactly where its coming from. But essentially, a power wire is too close to a signal wire somewhere.

 

[NotSoSlowSHO]

If this problem just started up, check for faulty grounds.

 

[Devin]

Eh, all my problems just kind of "started up" since I finally began driving the car, so it could be a legacy issue.

 

[Storm-Chaser]

Have you changed the ignition noise suppressor? I think it's referred to as the Radio Noise Capacitor.