Question: Odd sound (whistle) when accelerating/braking

John L

John L

A2OC Donor
I have an A2 1.2Tdi (2002 model) and have recently changed the rear breaks. I also have a problem with the ABS curently a sensor needs replacing which will happen soon.
However when driving I get a high pitch whistle (seemingly from the front right of the car) that varies in intensity when the accelerator or brake pedal is pressed. I have been told that the front brake pipe is mising a cover on the bleed valve and that there is some rubbing visible on it and this could be related.
I have no real idea where the noise comes from but the brakes feel sharp. The under engine plate is damaged (from a pothole) but this should not whistle. Also the whistle is present from around 30km/h upwards but does not get louder with speed. Therefore I do not think that it should be a hole in the body or anything like that.

I know the description is vague but would appreciate any ideas!
The noise is an annoying pitch but and quite quiet but I am keen to identify and fix it before it becomes serious.
 
Could it be a boost leak?
Front right is the intercooler (I think)
Just a guess

Access to VAGcom?
J
 
Would the noise of a boost leak be dependent on revvs and gear? In my case the speed and power do not seem to affect the volume of the whistle.
The pitch and noise level vary with application of the brake pedal more than with revvs. Higher revvs do not make the sound louder.
With two people in the car my passenger seemed to think the sound came from the centre of the car around the gear stick.
The pitch changes when the brake is pressed and almost disappears when full braking is applied but reappears after a second or so. The noise is also present when the engine is not doing much such as with eco mode enabled and rolling down a long steep hill. On the hill the engine shows 1000rpm or so and the noise varies with braking as elsewhere (sort of drops in intensity when braking is applied).
I tried to record the sound but on the test for this purpose the noise was barely audible.
I have scanned the car with VAG-COM and only found the ABS sensor error. Other than that there were no current and no stored errors.

I really want to fix this problem.....
 
Record a video from inside the car to provoke the sound with your phone and post it on YouTube, share the link here then we canwork it out!
 
Today the ABS sensor was replaced and the ABS and traction control are active again. The noise has stopped. It also had a long-life service and somwhere in this process all is ok again.
Also the car feels smoother and sharper again after the service!
 
It was a rear ABS sensor and the wheel bearing on that wheel was also faulty. I guess there may have been contact however I did not see the old one after the exchange. The sound definately did not seem to be from the back of the car.
The brake servo or something was also clicking quite loudly while the ABS warning was on and the car was in neutral when pressing the brake pedal.
 
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