Ghost in the machine, wooooooo sound at 45mph

Dale_K · 01-29-2011, 07:11 AM

This is a new-to-me 2000 S tiptronic I bought a month ago. Woooooooooo is the best description. Seems to be coming from the right front of the car. Doesn't sound ominous and goes away instantly if I let off the gas or give it more gas, although sometimes it persists even with the foot off the gas while coasting down a hill. Only does it sporadically under very light load and moderate speed and not all the time even then.

mikefocke · 01-29-2011, 10:03 AM

Front trunk lid too high in relation to bumper cover?

Dale_K · 01-29-2011, 01:26 PM

Can you spot anything from this?

WhipE350 · 01-29-2011, 08:08 PM

I have this too, it is a flute sound from the right front. I did a research a couple months ago and it can be fixed with either a new gas cap or one of these parts 99620123101 / 99660521301. It won't hurt anything but drives me nuts...it's on my list to fix. Both can be accessed from right from wheel well or behind right head light...let me know if you get it fixed...I'm going to do mine soon and will post results...I'll start with gas cap, then 99660421301...cheapest to most expensive (99620123101).

Hope this helps.

Garrytw · Garrytw's Garage

Dale, I have the same symptom on my '00, replaced the fuel cap, but didn't help. I have seen several posts, and have decided that it must be the vent valve mentioned by WhipE350.
Plan to replace them middle of next month. Good Luck.
BTW, nice little ride there!

Doug&Julie · 01-30-2011, 06:36 AM

Another suggestion...

Interesting noises coming from my '01 Boxster.

Dale_K · 01-30-2011, 01:44 PM

Thanks for the posts about the fuel filler system and part numbers. That's the area where the sound comes from.

WhipE350 · 01-30-2011, 04:33 PM

Quote:

Originally Posted by Doug&Julie

Another suggestion...

Interesting noises coming from my '01 Boxster.

It was 73 today in Charlotte and was really nice to feel the car in warm weather...but the flute was loud, I've heard enough and will go ahead and fix it...looks like a guessing game though...I flipped a coin and will do 996 605 213 01 first....not the highlighted one but #9.

Wayne 962 · Wayne 962's Garage

Can anyone guess what causes this? This one beats me? Is it air sucking in from the outside due to the pump pumping fuel? If so, then it should be speed independent (related to rpm / load, I would presume).

If it were my car with this problem, I would start taping off sections of the car with masking tape to see if I can isolate the noise. I'd start with taping the fuel filler cap gaps...

-Wayne

Dale_K · 02-02-2011, 04:32 AM

I drove the car to Little Rock this past weekend and spent more time driving at higher speeds and flatter terrain. The car will also make the sound at 60 mph. The constant in the whole situation seems to be a very light load on the engine. It makes me think it is related to engine vacuum.

I had considered the idea that it comes from an aerodynamic issue and had planned to mask off the fuel filler door. I might still do that but the door appears to fit well, although the locking mechanism no longer works (fine by me). I can see a slight missalignment of the right side headline housing in relation to the front trunk and trim but I don't think that is the source.

I feel pretty confident that one of the other posts about the gas tank vent system could be right. That poster seemed to describe the issue the same way I'm hearing it and they report complete success after replacing a "valve block". It's too cold at the moment to work on the car. My plan now is to tape over the fuel door and see what happens but even if that stops the sound I plan to pull the right side fender liner and look around. I plan to pull the front bumper cover too. It needs cosmetic work in any event.

WhipE350 · 02-02-2011, 08:14 PM

Quote:

Originally Posted by Dale_K

I drove the car to Little Rock this past weekend and spent more time driving at higher speeds and flatter terrain. The car will also make the sound at 60 mph. The constant in the whole situation seems to be a very light load on the engine. It makes me think it is related to engine vacuum.

Same for me, I had it happen going down my driveway the other day. I will say the warmer it is the more likely it will happen. Always seems to be under light load i.e. if I take my foot off the gas it goes away, if I throttle heavy it goes away. With a little more warmer weather I will try to isolate this instead of just replacing parts until it goes away. It can be very loud at times too, almost like when blowing on a bottle just right...the type of sound that travels easily. All the reading I've done has shown people getting positive results from replacing and taping different things...almost like taping prevents the air to the flute and in the case of replace parts, like a similar part is used in multiple places.

Wayne 962 · Wayne 962's Garage

Perhaps try driving around with the gas cap off and see if that makes a difference? That would be a good way of testing, I suppose. Don't have a full tank though.

-Wayne

Dale_K · 03-19-2011, 02:58 PM

Update on this wooooo sound. I replaced a valve block today that's right under the filler opening behind the fender liner. I don't really understand the vent system and I just guessed when I ordered this part. I was getting some other parts from a place that has a $75 minimum order requirement and needed to pad my purchase to make the minimum so I took a risk and bought this part. Actually this is the old one.

The upshot is that replacing this valve didn't fix the problem, so save your money and don't bother doing what I did. I played around with the old valve and discovered the functionality... it permits bidirectional air flow between the two ports whenever the gas cap is tightened. With the gas cap off it will still flow in one direction only. But my car still goes "woooooooo" under light throttle pretty often.

So if anybody else develops the known fix, I'm interested.

Wayne 962 · Wayne 962's Garage

I would check to see if the vent pipe / hose connection to the charcoal canister is properly connected...

-Wayne

WhipE350 · 03-20-2011, 06:37 AM

Dale, what part # or numbers does this piece represent...see my diagram several posts back, I still haven't fixed mine so any info will be helpful.

Dale_K · 03-20-2011, 09:15 AM

The invoice identifies it as "Fuel vent valve" with a number 9962011430. I don't know if that is a part number or just a stocking number by the vendor. I don't see it in your picture.

Another thing on my car that might be a clue is that I often cannot get the gas to go in the tank very well when trying to fill up. For example after installing the valve I could only get 3/4 of a tank per the gauge but sometimes it used to do the same thing with the old part.

I'd like to check out the plumbing to the charcoal canister but I don't know how to do it or where the canister or vent tube are located.

Zeke · 03-20-2011, 03:05 PM

Some of this stuff is behind the RF inner wheel house liner.

WhipE350 · 03-20-2011, 07:08 PM

Quote:

Originally Posted by Dale_K

The invoice identifies it as "Fuel vent valve" with a number 9962011430. I don't know if that is a part number or just a stocking number by the vendor. I don't see it in your picture.

Another thing on my car that might be a clue is that I often cannot get the gas to go in the tank very well when trying to fill up. For example after installing the valve I could only get 3/4 of a tank per the gauge but sometimes it used to do the same thing with the old part.

I'd like to check out the plumbing to the charcoal canister but I don't know how to do it or where the canister or vent tube are located.

Part #12 on the filler neck is what you installed. I hoping I can still get the used parts I mentioned and try it...in the mean time I flute along

Wayne 962 · Wayne 962's Garage

Let us know what you find out!

-Wayne

Dale_K · 06:25 AM

The vent valve only cost $40 if you decide you need it. I ordered a Durametric yesterday from Pelican to help me run down a CEL and check my MAF readings and at the same time I ordered a new gas cap. I doubt that will help but at $15 it's worth a shot. I'll add a post here after I've had it on for a few days.

I'm still looking for some pictures of the tank vent/charcoal canister system.

Edit... found a bunch of threads about the charcoal canister and some related to the woooo sound. Looks like the valves you show above might be it. Also I see the Durametric can activate the evap purge system, which is related to this sound. I might have a complex combination of stuff on my car. I'm getting 1126, 1128 and 1130 codes that indicate a vacuum leak or MAF problems and I also get the woooo sound that is vacuum related. Maybe the woooo sound is something in the evap system that is creating an intake leak. Maybe I should focus on the evap system and woooo sound first in the hope it also corrects the other codes. Funny that I don't get any evap system codes though. This is getting too hard for me to understand.