Whistling Noise when accelerating

I

Ilykhn

Member
Hi All,

I checked the forum and noted this problem has been highlighted before. I just wanted to follow up having recently had my Z4 checked by my local BMW dealer. The noise on my car appears when I accelerate hard, either from standstill or whilst cruising. The noise itself last only for a second or two and then goes.

The mechanic at the dealer told me this is because the fuel pump has to work harder under extreme acceleration and this is common across all BMWs (the whistling noise).

Can anyone confirm this to be true? The noise is driving me mad.

Ily
 
Welcome to the forum Ily :)

Firstly i think youre dealer is telling you a complete load of porkies :headbang: Fuel pumps shouldnt make that sort of noise and if it did, it'd be knackered anyway!

If you can provide any other details they would help us loads including which engine you have, and a video/audio capture would help lots... Is the noise coming from the front (engine)? What pitch is the whistle (like a human whistle or higher pitched)? What throttle percentages does it do this (Just 100% or even under partial load)? Does the pitch of the whistle get higher with increasing throttle/speed?

My initial instincts tell me that it could be a slipping belt or auxiliary pulley issue. If higher pitched (more of a squeal), it could be the sound of air rushing past the throttlebody; my old VX220 did this lots, sounded like a trapped mouse!!

EDIT: If the car is generally running fine and smooth, that basically rules out any airleaks. You should also check the PCV (Positive Crankcase Ventilation) hose on the rocker cover to make sure it isnt cracked. Its a rubber tube that runs from the rocker cover to the inlet manifold :)
http://www.realoem.com/bmw/showparts.do?model=BT52&mospid=47797&btnr=11_2194&hg=11&fg=15
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Mine has the same noise, only on light blips on the throttle or under heavy acceleration.

I have been informed by an independent its mroe than likely the DISA unit.

The car is booked in for warranty work on the 7th
 
Hi Again,

Thank you for the detailed replies. My BMW is a 2008 model Z4 3.0si Coupe.

The whistling noise occurs when a press the pedal 15% down. To me the noise seems to be originating centrally from within the engine. The noise in my opinion is quite loud as you can hear even with the radio on. Otherwise the car is running perfectly fine. There is no noise when I am gradually accelerating (10% pedal down) only occurs if I push the pedal down 15% or more. The noise itself only lasts for a second or two.

I plan to go back to the dealer next week but I would like to be armed with sufficient information to present my case and to ensure I have them take a good thorough look.

Ily
 
Hi there...

I could be way off here but I had a similar problem - a slight whistle/vibration when I accelerated and it was a broken bracket on the exhaust... cost me £7 to replace?

Just an idea?!

Ames xxx
 
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