Problem with a 2006 Buick rendevous rado (AM only static) when car is on

Whne the radio is on AM and the car is running, there is static . When the car is turned off and the radio remains on, the static disappears. We have had the antena replaced, the radio replaced and all worked for a while but now the static is back. Help!!

Bad spark plug wires can cause a similar issue, is it random static or does it increase with engine speed?

Static remains the same.

I remember years ago when installing aftermarket stereos (since the factory ones used to be such junk), I always used an in-line power filter to clear up that static. Similar to this, they can be had for less, at several places. Search around and see what you can find. Depending on what’s introducing the noise (typically the ignition system, but sometimes the charging system, too) one migth work where the other doesn’t.

Here’s an article that you might like to read.

I suspect there is a problem with the antenna connection to the radio or the antenna connection to ground is bad. It is very important that the antenna ground bonding be good for clear AM band reception. Though the antenna and radio were replaced the antenna cable between them may not have been worked on. Bad antenna grounding or a poor antenna connection will allow all kinds of noise to over ride the AM signal. A shop that specializes in car audio may be a good place to take this problem to.