audijim113

the hard part is to describe the noise. It's sort of like a soft honk of a Canadian goose without "H" of the "K" ooon, ooon. It is not very loud and seems to be coming from the front passenger side. It is noticeable when starting out from a stop under gentle to moderate acceleration. I can duplicate it at any speed from 10 to 50 by slightly increasing pedal pressure. If I let up, the noise stops. Frequency between the "ooon ooon" increases with more acceleration. With heavier (not pedal to the metal) acceleration, it seems to be constant. oooooooooooooooonnnnn but it is not very loud and other noises make it difficult to hear. At first, I thought it was coming from a revolving wheel or rotor but it does not increase (time between ooon, ooon) with speed. The only thing that makes it more pronounced or rapidly repeating, is acceleration regardless whether from 0-10 mph or 40-50 mph.

Would love to record the noise and post an audio file but don't know how to do that. I could record it with my smart phone with a "voice recorder" app but I'm not sure if it would pick the sound over road noise.

Taking a shot that this might recognizable by someone else. I realize this is a long shot.

sbcrazy

Could be 2 possible things. The pcv valve on top of the engine and/or transmission. Do you hear the noise in neutral or when you first start the car.

MP4.2+6.0

I'm thinking this was maybe one of the descriptions for the 4.2 world's most expensive PCV valve acting up. Does that ring a bell with anyone?

Meanwhile, your description may be tied to motor running conditions where the vacuum level is dropping as you push on the gas pedal, and why it can occur over a range of speeds. Could also fit PCV valve operation--the flat topped black plastic circular part several inches in diameter toward the back of the motor high up with two connected hoses on the underside. There is also the little known suck pump--basically an in line Y connector (it is NOT a pump even though often called that for some reason in Audi parts slang) in large diameter vacuum related hoses that has a one way check valve plastic ball bearing sort of thing inside it. On my C5 4.2 that was back by the firewall near the master brake cylinder. My W12 has one too, where it is close in the the rubber intake hose fitting between the MAF and the throttle body.

sbcrazy

Is this the sound?

Here is a possible fix without replacement.

Audi Addict ? PCV "hunting" noise - solved...after 2 years

audijim113

Bingo. That is exactly my Canadian goose noise.

Had a hunch someone on this forum would know.

audijim113

Everyone is invited for Sunday dinner. We're having roast goose.

audijim113

I see what you mean about world's most expensive PVC valve. I see products ranging from a Viaco product selling for $28.00 to $135. However, the Viaco does't look the same as the "genuine OEM" on this site:

05 2005 Audi A8 Quattro Crankcase Vent Valve - Engine Mechanical - Beck Arnley, Genuine, Vaico - PartsGeek

Then I found one on ebay for really cheap $17.59 that looks right but the compatibility says it's not right for 2005 A8.

http://www.ebay.com/itm/New-4-2L-Engines-Crankcase-Vent-Valve-For-Audi-Volkswagen-077103245B-/181329272632?fits=Make%3AAudi&hash=item2a38111f38&vxp=mtr
Ironically, there's one that says it's compatible with 2005 A8, but it doesn't look the same. It looks liike the Viaco and it's also cheap. $19.

http://www.ebay.com/itm/New-Engine-Crankcase-Vent-Exhaust-Valve-Audi-06C103245-/291142603433?fits=Make%3AAudi&hash=item43c97392a9&vxp=mtr
What am I missing and will the cheap part not work or be too low quality?

http://www.ebay.com/itm/New-Engine-Crankcase-Vent-Exhaust-Valve-Audi-06C103245-/291142603433?fits=Make%3AAudi&hash=item43c97392a9&vxp=mtr

sbcrazy

Read the reviews and that might help

Panelhead

It was less than 28.00 then. Works perfect on my 2005 4.2.
It was not acting up, but at 75,000 miles and 10 years it was a good 20.00 expense.
Replaced the one on my 2006 XJR. These have so much in common, aluminum body, air struts, 6 speed ZF, 4.2 liter engines, and the same looking PVC or crankcase vent valve.

MP4.2+6.0

So I pulled 077103245B as the part # from Euro EKTA for a 2005 4.2. Audi - A8Q - 2005 - Engine, Clutch Teile Katalog (Pats Catalog) That seems to be the part # right on the one from Amazon that you can make out in the picture for $36. You can type part # in Google, but a quick scan of hits and that one seemed very good for supposed OE/OES. AudiUSAParts (on line discount dealer) is just over $100, confirming the usual world's most expensive PCV.