My 98 A4 2.8 30v Q officially turned 200k last week. I had a couple of my buddies in the car and wouldn't let them out until it flipped. They even cheered a little.
Anyway, you know the airplane sound (can't find a sticky) well my airplane has taken a hit and is spiralling towards earth. It now grumbles and groans like bearings or blades are going bad. I am not familiar with this part at all. What is it? Does it pressurize the vac system? Where is it? What happens if it fails completely? Any help appreciated or steer me to the topic here. I have the Bentley manual and am eager to get at this thing. Thanks.

 

can you explain the airplane sounds is it when u floor it?

 

^^+1... wtf is airplane sounsd? like a 747 or a cesna>? lol

 

mine sounds like a whining noise like an exhaust leak which is wat i think it is. not exactly sure info would help keeping an eye out on this post

 

When does it happen? While driving? Does it change depending on road or engine speed? Is it at a standstill when the engine is cold? Need more info to diagnose the problem.

 

I think I know he's talking about. I have the same noise and it happens when I initially start my car from a cold start. It goes on for about a minute and a half then goes away. Sounds JUST like an airplane on the runway.

Not sure we're on the same page but I got the airplane sound.

 

From cold-start it's likely the secondary air pump. Watch the tach - does the noise die at the same time your RPM drop? That's the culprit. Coming soon - CEL and an inability to pass smog. The pump is the cylinder in the lower right corner of the nose (on 30v engines anyhow). New one runs $300 I believe.

 

Yup, you hit the nail right on the head with the RPM thing. Guess I got to dig back into my pockets.

Thanks...even though I didn't start this thread.

 

Sorry about the poor description. Yes it is at idle and yes it is in correlation with the rpm. Secondary air pump ... great thanks. Now I can address this. Where I am my car is emissions exempt. Thankfully too because of bad cats! Thanks again Imthedevil and all y'all.

 

If you're emissions-exempt, look up twenty square. There's a resistor and blockoff plate mod you can buy to eliminate the SAP. Saves hassle although you'll have an incorrect airflow code. If you have emissions, that code will fail you. If not, do it up.