Noise coming from gas filler area.
 

Hello all,

I have and 03 Boxster S. It has some surging generally associated with a dirty MAS. I plan on cleaning it, but something new has arrisen. From time to time, I get this strange howling (it sounds like noise you get when you blow over a large Coke bottle) coming from the gas filler area. Any ideas what it might be?

Tony

Stick a sponge in it. ;)

This seems to be a common fault. It’s caused by a faulty filler cap I believe.

Buy & install a new Bosch MAF sensor, if it dosen't improve performance clean your old one & save the new MAF for the next time you think the MAF is suspect. You will need it sometime. I think you can buy a new sealing ring for the gas cap.

I put a new gas cap and my car still does this.

And for some reason the noise from the gas filler, is dependent on the throttle. If I rev the car, the noise goes away from some reason. I have a feeling it's due to the pressure gnerated by the pressure regulatror. That's just a guess.

Tony

if the noise is coming from the small hole under the gas filler door to the front of the car from fuel filling area, then it is the evap emissions valve.

OK, I took the MAF out and cleaned it. Am I supposed to disconnect the battery an have the ecu re-learn the idel after I do that?

Tony

bump... anyone?

Not necessary. The MAF isn't powered when the ignition is turned off.

You didn't take my advice about the sponge? I didn't invent that recommendation. It's been posted before.

MAF? Pfffffffft.

Perhaps the evap valve.

Look for a hole in the tank fill area.... put it a piece of sponge... that would revise the pressure... and would cancel that irritating resonationb. Dude. A piece of sponge... maybe the size iof a few pencil erasers. Look it up on these pages.

Best wishes.

So, the 2 issues I'm having are the pulsing idle and the coke bottle sound coming from the fuel filler area. I've replaced the MAS, and the evap valve (and tried sponge), but both issues persist. Ant idea what else could be causing these issues? I'm planning on replacing the gas cap.

Also keep in mind that I'm not getting any CEL.

Tony

Oil Air Separator
 

Oil Air Separator

For the surging at idle, right? What about the noise from the gas filler? Also, I changed the AOS 20k miles ago. I find it hard to believe it's dead already.

You could always do what I did , shoot a lot of guns and work in construction for 30 some years without hearing protection. Then you won't hear those pesky noises anymore

I believe there are 2 emission control valves that vent to the whole under the gas filler door.When i replaced mine i was worried that the one i replaced might be the wrong one....but it fixed it. in your case you might have not replaced the one causing the noise. the issue is exactly as you describe. blowing over a coke bottle sound coming out of the whole under the gas filler door.

If you have a Durametric and want to test the valves see this post #6 and #7

http://986forum.com/forums/boxster-general-discussions/75684-hard-restart-after-fueling.html

I temporarly fixed the issue on mine by putting a small piece of masking tape to partially cover the vent hole(half of it). The one located a 3 oclock in the housing.
A foam would work as well !