Ignition noise on radio, intermittent, not alternator whine

I noticed something new the other day while driving home, a steady ignition noise over the FM radio on all stations. It wasn't alternator whine, but more of a steady buzz that didn't seem to change much with engine RPM, if at all, unlike alternator whine which changes pitch with RPM.

I did verify that the noise was gone when the engine was off, but didn't get a chance to see if the noise was also present on non-radio CD playback.

The sound went away today so I haven't had a chance to do any other testing.

Not sure what would cause this, but I the ignition module was replaced when the shop was troubleshooting what turned out to be a bad PCM. Not sure if that could be related?

Any ideas?

Al

Look in about a 1-foot circle of where each bit of troubleshooting was done, find and fix loose grounds.

Remove the coils and icm, clean the grounding plate, wipe on a thin even layer of dielectric OR conductive grease, reassemble.

Thanks!

It seems to have magically 'gone away' in the last week, but I'll still do what you suggest as I don't like mystery events like this that just 'go away' ... as they'll probably come back.

I was thinking along the same lines