Popping sound from rear driver's side of car.
 

I noticed today when I got home my car was making a popping sound from the back of the car near the wheel. it can only be heard outside the vehichle. anyway I got under the car to listen and it was what appears to bea rubber flap near some white plastic causing it. there's also some kind of vaccuum going on under there that keeps pulling this thing up. anyone have any ideas on what this could be>? I've never heard of anything liek this on the forum before. again, the piece making the sound is right behind the rear wheel and maybe part of the rear reflector or gas cap area? a small rubber piece keeps flapping. any help will be appreciated.

it's right by the fuel tank and only flaps/pops when the cabin vents are running. still does it after all this time, still not sure why.

Flapping: probably someone put a playing card in your spokes...:D

Actually i have never heard anything like this either...the closest thing that I have heard to this (which I am experiencing now) is the rear bushings which make more of a clunking sound...

Does it quit making the 'popping sound' when the cabin blower is operating AND a door or window is open, too? If so, this could be some type of vent that relieves the internal air pressure created by your blower; in other words, an exhaust vent. I've seen similar vents on other vehicles. My search of the ’93 and ’95 manuals didn’t find any references.