It just started today when I started the car up I heard this whining noise from in the car and I revved up the engine and it got louder and then as the rpms went down so did the noise. Could it be the tach or something. It is really annoying.
Please help!
Thanks!
Brent

 

It's called alternator noise. Several things could cause this. If you have an aftermarket stereo or components (amps, crossovers, etc.), check to make sure all power sources are properly grounded. Also, ensure that your audio inputs do not cross or run next to any power wires. Another thing could be weak conductor insulation in your spark plug(s) allowing interference to leak out.