Hello British,
What sticks out to me, is that you said when you were in the drive thru at WC with the window down, it was much louder, that to me means it is from outside the vehicle and nothing to do with your sound system, what year is your vehicle, and remember that the engine is making vacuum at idle, but when you are on the gas you are making boost, so if you have some vacuum leaks and the system calls for vacuum because of leak, the pump will come on even though you are on the gas, and if that is the case then the vacuum pump is working overtime and will fail soon.

As you say it does not change pitch (sound) with rpm range, I can not think what else it could be at the moment, if you did have rpm related sound I would be looking at the belt and all belt driven components, do please try to get a recording, by any chance is it like a whistle, maybe air intake hose, just thinking out loud.

Johnny

 

I think that is it. I tried to get a recording, but it is harder than it sounds, it sounds just like background noise, I don't know why the phone won't pick it up.

What you're saying about boost sort of makes sense, but the pump, if it's the pump, goes on not with boost, but with pressing the gas pedal. Clearly it's a computer-controlled switch-on. Does this indicate a vacuum leak? Sometimes it runs, sometimes it doesn't, it seems to make the "tone noise" when at a stop and I press on the gas, it clicks on.

I haven't been able to replicate the White Castle experience, the pump is not running 100% of the time (if it's the pump) it sometimes only runs while I'm pressing on the gas, sometimes, like at White Castle, it was running at idle.

I have ordered the Audi replacement part, assuming that's it.

 

Okay, just so we are on the same page, while you were in line at the drive up, are you saying that you had it in park and pressed the has pedal and the noise came to life, if that is the case then I think you're correct as to the boost I suggested with no load on the engine, I know it's not the same vehicle but I just pulled in a parking spot to check amount of boost in park and no load on my S600 V12TT using an app with vacuum/ boost gauge, and you are correct as to no boost revving the engine in park.

What about standing further from the vehicle while recording while someone gives it throttle to see if you can pick up the sound.

Johnny

 

The easy way to eliminate the vacuum pump is to open the left door, start the engine and keep pressing the brake pedal until the pump kicks in. If it's getting loud you will definitely hear it as it's just in front of the door in the wheel well.
I fitted an Audi A8 pump when mine failed.

 

Hello @British ,
What was the outcome of this ?

JJJ

 

A thousand bucks here…a thousand bucks there…


It worked fine but was super-noisy. I had them replace it, I can still hear it from time to time, but not like before. I don't know if it was worth $1,000, but it really was an annoyance, made the car seem like it wasn't running right.

This was just part of a bigger bill for more work, the labor actually seems pretty high, I doubt it took three hours, but maybe it did, they're pretty honest with me at my independent.

I made the decision when I bought a used car that I was going to use the money I saved from buying new to keep it in perfect, "like new" shape, so I could enjoy it, so I haven't begrudged any repair so far. The only thing I really needed to do was the wheel bearing, that made it super-unpleasant to drive and would only get worse.

I think I'll change tires at the end of the summer, I bet that makes a nice ride improvement too, not that it's riding poorly

I haven't driven it in four months or so, my housekeeper takes it out once per week to keep it charged up, no check engine light so far