Only with the engine running I get loud static noise when listing to AM stations. I've tried different antenna, different ground, different positive for both positive lines (the constant & the keyed), still the noise. The car is an 89 IROC with 5.7 engine and the radio is a Sony CDX-MP70 that has been in the car 4 years. Any ideas?

 

Good luck. My old anger always had AM engine noise. Tried installing a AM filter, which was basically like a RCA ground loop isolator, but it never worked. I remember buying it at Radio Shack, but that was years ago. Eventually I just stopped listening to AM all together..... Lol

 

Check your antenna connection carefully. You said you replaced the antenna.. Did you check the wiring running to the antenna for breaks? When you say you have static, is it a "whine" that increases/decreases with engine RPM or just static? Has this been an ongoing problem for all 4 years or is this something new?

 

weird

 

Is it good reception but also with loud static noise?
Or is it just static and no reception?

If you still have good reception but also have the noise, does it change with the engine's rpm?

If it does, then you have an ignition noise coming from somewhere. Could be bad plug wire(s) or a plug(s). Be sure you're running resistor type plugs (most today are). As for the plug wires, be sure they have good RF suppression and are in good shape. As plug wires age the insulation gets brittle and the core can develops cracks. You might not even be able to see this, but it can a horrible source of ignition noise. Same thing if a plug wire is close too or touching any metal like the valve covers, engine block, etc.

Far better to go after the source than to try to put a band-aid (filters, etc) on it. And you might even improve your performance.

Good luck.

 

I installed the radio 4 years ago when I gave the car to my son & it didn't make the noise then. When it started I don't know as he rarely listens to AM. I just installed new plugs (AC Delco) wires (8mm MSD) cap (MSD) & rotor (AC Delco). No change. The AM comes in very clear with the engine off, with the engine on you hear the static and it gets louder when the engine RPMs go up. It's not a whine. Anyway, I've ordered a new radio from Crutchfield, scheduled to be delivered Tuesday. I'll install it next weekend, hope that solves the problem.

 

I'll post (next weekend) to let everyone know, if the new radio cures the problem........if not, I'll rewire everything including the speakers