Smokey,

I think I might have an idea what your problem popping sound could be. You will have to do some experimenting to confirm/disprove it.

Cell phones receive signals that we usually don't hear. But when the phone is near speakes or sound equipment, these signals come through speakers as a series of popping sounds....

If you have your phone near your head unit in your car, it might be causing the noise you hear. Mine sometimes does it through the radar detector speaker I installed (I keep the phone either on a strap on the passenger seat back or down next to the emergency brake)

Strangely, no matter how loud or soft the speakers are set (including turned all the way down!) the popping still comes through the speakers.

The only way to stop it is one of the following:

- turn off the stereo completely
- turn off the phone completely
- store the phone far enough away from the stereo and speakers

You should be able to easily test this. With the car running and the stereo the way you usually have it, and your phone where you usually keep it, have someone call you or text you. Or the next time it happens turn off the phone and see if it stops.