Fwap,fwap,fwap
 

The car, not me.

I'm getting a fwapping sound, consistently about 3 fwaps per second. 90% of the time when it happens it's during deceleration. It doesn't happen during all decelerations. By decelerating I mean the car is slowing down. With or without braking, with or without downshifting. Not rpm related. All insulation has been removed and it sounds like it could be in the trunk area, maybe on driver's side. Electrical? Fairly loud. No fuel problems and is louder than a typical fuel pump but I am not familiar with Boxster mechanics yet. I also don't think it's axle rotational due to consistency. Lasts maybe 10 seconds. If I accelerate it doesn't respond. It's a very distinct sound but I haven't been around Boxsters long.

What say the hive?

what about if you're not in gear at all? Still make the noise? Does revving the engine while decelerating make it stop?
Have you checked the undercarriage?
Intrigued to find out what is causing this.

In or out of gear makes no difference. same as engine. I need to check undercarriage but the sound is consistent no matter what. That's why I was thinking electrical or the forward force was causing something to run dry, maybe? Like a pump running dry.

Have you checked the PS reservoir? I've seen a few of those dry. Black plastic cap on top of the engine right behind the driver's seat firewall.

Based on description of sound, could it be a broken belt in a tire?

I think you have it! Dry! I'm planning on removing the power steering so didn't consider that. I'll pick up some fluid tomorrow.

THANKS, 78F350!!!

Great, I hope that's all it was. Just make sure to get the right stuff. I expect you know, but Not the regular U.S. Power Steering fluid. CHF 11S, CHF 202 or equivalent Hydraulic System Fluid.

Yes, thanks, the correct fluid is the problem. I'll check at NAPA, the only parts store for about 25 miles. In the 1 1/2 years I've lived here I have seen one 944 (V8), one 914 (V8), and one very nice 911. Plenty of tractors, though.

Pep Boys sells Pentosin CHF

Do you have the factory sport exhaust? Mine makes a similar sound on deceleration and my mechanic pinpointed it to one of the valves in the sport exhaust.

I added the steering fluid - no change.

I have a Dansk Sausage. Not sure if it has valves.

did you check the undercarriage or wheel liners? I once had a loose front wheel liner that was making a fwap-ish noise.