The Mach 460 Stereo system in my 94 convertible is making a growling noise when the engine is running. Kind of an "Rrrrrrrrrr..." noise whose frequency increases with engine speed. It is quite loud and is independant of the volume setting. What I mean by that is I can turn the volume all the way down and the volume of the noise does not decrease. It seems to be coming from all speakers. The funny thing is when I turn the engine off, the noise doesn't go away all at once, but gradually decreases over 10-15 seconds. The character of the noise changes from a growl to a more generalized "pink noise" type of thing once the engine is shut off. Once the engine is off for a few seconds, the system plays normally with no spurious noises.

The system is a stock Mach 460 without CD save for an Audiovox CD changer installed via a transmitter in the antenna line. The noise is present no matter what source (CD, tape, radio) I'm listening to. The transmitter is located on top of the front amplifier. I did have this problem (though not as bad) before the CD was installed and it was dealt with by the dealer under warranty. I'm leaning towards a bad ground or a noisy power line.

Has anyone experienced this and if so, how did you solve it?

 

done any work to the ignition suck as a MSD?

 

No, the car is bone stock in every way except for the aftermarket CD changer.