Vacuum Leak on Acceleration?

ChuckyUK · 07-21-2016, 11:56 PM

Hi
I've had my X1 for 5 weeks now and it's been great. 3 weeks ago a noticed a whistle/air leak sound whilst accelerating. You can't hear this with all windows up but it's very prominent with the windows wound down . I'm wondering if anyone else is experiencing this noise ? The car is booked into BMW for next Thursday.

Saintsman · 07-22-2016, 12:57 AM

Is it just turbo noise Chucky?

Les Paul · 07-22-2016, 02:07 AM

I get the same at about 1600/1800 rpm -only really noticable with the window down and under acceleration - I guess it is the second turbo cutting in, I used to get a similar noise on my petrol Audi turbo. There was another thread about this a while back, I think one poster got there turbo vanes replaced. I'll be interested to hear what your garage say. I've done about 8K and it's been there since new.

CliveL · 07-22-2016, 03:29 AM

Does the noise happen at all times in a trip, or only when the engine is warming up? The reason I ask is that there is mention in the technical documentation for the engine that suggests some noise when cold is by design as the wastegate valve is opened to allow the catalytic converter to heat up as quickly as possible:

Catalytic converter heating
When starting the combustion engine from cold, the wastegate valve is opened as wide as possible and the ignition point is adjusted to retard. The retarded ignition point delays the combustion process which in turn supports the heat input for heating of the catalytic converter. As the turbine housing is short, it has been possible to position the catalytic converter very close to the wastegate valve. As the exhaust gas flows into the catalytic converter at the perfect angle and because of its position close to the engine, the catalytic converter reaches its operating temperature very quickly. If the wastegate valve is opened when cold, pulsation of the exhaust gas may cause vibrations in the wastegate valve, which are perceived as noise. This is not due to a defective component, and is normal running noise. This noise becomes less audible as the temperature of the component increases.

ChuckyUK · 07-23-2016, 12:40 AM

Thank for the responses guys. The car is showing 45.3mpg on the OBC over the last tank but according to my calculations has 39.2 mpg. That's quite a difference - so I'm assuming something is amiss! The hissing noise can be quite loud too. I understand your point about the engine warming up but the outside temp is about 26C so it shouldn't take long . It certainly is louder from cold and reduces with a driving but it's always there!!

sdb123 · 07-23-2016, 03:16 AM

Every BMW I've had has had variances of approx. 10-15% when comparing the Onboard computer to actual fuel consumption.

dj_intrinsic · 07-25-2016, 01:53 PM

Combination of turbo spool and e-wastegate. Totally normal.

07-21-2016, 11:56 PM	#1
ChuckyUK Enlisted Member 16 Rep 42 Posts Drives: BMW X1 xDrive25d xLine MW Join Date: May 2014 Location: Yorkshire iTrader: (0)	Vacuum Leak on Acceleration? Hi I've had my X1 for 5 weeks now and it's been great. 3 weeks ago a noticed a whistle/air leak sound whilst accelerating. You can't hear this with all windows up but it's very prominent with the windows wound down . I'm wondering if anyone else is experiencing this noise ? The car is booked into BMW for next Thursday.
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07-22-2016, 12:57 AM	#2
Saintsman Private First Class 39 Rep 117 Posts Drives: X1 2.0i x-drive Sport AW Join Date: May 2016 Location: Cambs iTrader: (0)	Is it just turbo noise Chucky?
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07-22-2016, 02:07 AM	#3
Les Paul Private First Class 38 Rep 103 Posts Drives: X1 2.0D Xline Auto Join Date: Nov 2015 Location: UK iTrader: (0)	I get the same at about 1600/1800 rpm -only really noticable with the window down and under acceleration - I guess it is the second turbo cutting in, I used to get a similar noise on my petrol Audi turbo. There was another thread about this a while back, I think one poster got there turbo vanes replaced. I'll be interested to hear what your garage say. I've done about 8K and it's been there since new.
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07-22-2016, 03:29 AM	#4
CliveL First Lieutenant 163 Rep 334 Posts Drives: 2016 X1 F48 xDrive20i xLine Join Date: Jun 2016 Location: Bournemouth, UK iTrader: (0)	Does the noise happen at all times in a trip, or only when the engine is warming up? The reason I ask is that there is mention in the technical documentation for the engine that suggests some noise when cold is by design as the wastegate valve is opened to allow the catalytic converter to heat up as quickly as possible: Catalytic converter heating When starting the combustion engine from cold, the wastegate valve is opened as wide as possible and the ignition point is adjusted to retard. The retarded ignition point delays the combustion process which in turn supports the heat input for heating of the catalytic converter. As the turbine housing is short, it has been possible to position the catalytic converter very close to the wastegate valve. As the exhaust gas flows into the catalytic converter at the perfect angle and because of its position close to the engine, the catalytic converter reaches its operating temperature very quickly. If the wastegate valve is opened when cold, pulsation of the exhaust gas may cause vibrations in the wastegate valve, which are perceived as noise. This is not due to a defective component, and is normal running noise. This noise becomes less audible as the temperature of the component increases.
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07-23-2016, 12:40 AM	#5
ChuckyUK Enlisted Member 16 Rep 42 Posts Drives: BMW X1 xDrive25d xLine MW Join Date: May 2014 Location: Yorkshire iTrader: (0)	Thank for the responses guys. The car is showing 45.3mpg on the OBC over the last tank but according to my calculations has 39.2 mpg. That's quite a difference - so I'm assuming something is amiss! The hissing noise can be quite loud too. I understand your point about the engine warming up but the outside temp is about 26C so it shouldn't take long . It certainly is louder from cold and reduces with a driving but it's always there!!
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07-23-2016, 03:16 AM	#6
sdb123 Second Lieutenant 45 Rep 274 Posts Drives: F48 X1 M-Sport Join Date: May 2010 Location: Northants iTrader: (0)	Every BMW I've had has had variances of approx. 10-15% when comparing the Onboard computer to actual fuel consumption.
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07-25-2016, 01:53 PM	#7
dj_intrinsic Second Lieutenant 330 Rep 235 Posts Drives: 23 G80 M3 6MT Join Date: Oct 2013 Location: Bay Area, CA iTrader: (1)	Combination of turbo spool and e-wastegate. Totally normal. __________________ 2023 G80 MT / AW / Fjord Blue/Black \| KW HAS \| Apex VS5RS F:20x10+8 285/30-20 R:20x11+18 305/30-20 \| Maxton Street Pro Splitter \| OEM M3CS Grille \| SST Valve Controller \| CS Style Yellow DRL \| MAD Non-Res Single Midpipe Past: 2018 X3 M40i \| 2016 M-Sport X1 \| 2013 MT M-Sport 328i \| 2021 Audi A6 Allroad Last edited by dj_intrinsic; 07-25-2016 at 02:33 PM..
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