patela

my gas cap is making a purring/puttering sound! A few months ago, I lost the gas cap for my car. ('98 A4 2.8QT) Fearing the $30 charge from the dealer for a new one, I went down to the local Kragen Auto Parts Store, and bought an after market one for $3-4.
Fast forward to this afternoon. I stopped the car to unload some stuff from the trunk, and noticed this puttering noise. (The car was still on.) At first I though it might be a hole in the tailpipe or something, but it seemed to be coming from the rear passenger wheel well. Well then I realized that it was coming from inside the fuel door. I opened the door and sure enough, the noise got louder. I took the cap off, and the noise went away. I put it back and it reappeared. It looks like the cap has some kind of vent assembly. Is there a problem ?
I haven't had the CE light come on in a long while, but I do get terrible gas mileage. (13-21mpg) Are these things related? I'm planning to get an audi cap on Monday, now that I notice the noise, but does anyone have more thoughts about this? Could the cap the the source of my mileage woes?

thanks

Bryans12v

End of problems.

dr.audios[the OG]

I got one for $12 from the dealer