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#1
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Strange Whistle on Cold Start
I replaced my boot already so it's not that, just curious has anyone had any similar issues only on a cold start, sounds like a supercharger
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2004 E53 3.0i • 185K Miles |
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#2
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It's likely the secondary air injection pump. Mine whistled at cold start up too. Eventually, it threw a code for it too. Tried three different air pumps. Finally, a third pump turned off the code. I'll have to look up the brand. It was RockAuto most expensive air pump.
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'06 X5 3.0i - bought @143,123 miles (12/26/20) |
#3
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The auxiliary air pump will make a vacuum cleaner like noise on cold start but you should notice that without the car moving as well.
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1988 325is (purchased new) sold 2004 X5 3.0 2005 X3 2.5 2008 X5 3.0 (new to me) |
#4
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Quote:
only happens when I drive the car, on idle she's perfectly quiet and no issues
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2004 E53 3.0i • 185K Miles Last edited by Serb404; 12-04-2023 at 03:31 PM. |
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2004 E53 3.0i • 185K Miles |
#6
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The code on mine cleared with a HELLA*728124190.
Check the air injection pump hoses. https://www.youtube.com/watch?v=k400njcEvA0
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'06 X5 3.0i - bought @143,123 miles (12/26/20) |
#7
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Quote:
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2004 E53 3.0i • 185K Miles |
#8
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I guess it's possible that the air pump might only be noisy if there is extra back pressure from the exhaust ?? Does it seem to change with that in mind ? (on coast or accel)
You should be able to hear the air pump running on a cold start and then maybe listen for when it quits before driving away so you get an idea of what it sounds like.
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1988 325is (purchased new) sold 2004 X5 3.0 2005 X3 2.5 2008 X5 3.0 (new to me) |
#9
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There is the valve that goes from sap into the exhaust. If that isn't opening full or some other issue I could see it making a whistle. Too coincidental of the cold start and 90-120 seconds to really be anything not sap related.
Usually the bearing fails and it will make a horrendous noise like the car is trying to hover.
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2011 E70 • N55 (me) 2012 E70 • N63 (wife) |
#10
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Quote:
Quote:
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2004 E53 3.0i • 185K Miles |
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