weird sound from engine with throttle release

torqueisking · 01-22-2017, 12:48 PM

I'm hearing a sound from the engine bay which is like a vacuum cleaner powering down when I let off the throttle (from 50% or greater) in my X5 35D .

Not 100% sure because it is subtle but it feels a bit slow and mileage seems worse but that could be the colder weather.

I'm stock except for EGR block.

I think it's an intake leak but I'm able to hit full boost as displayed by Torque and I can't find any leaks. Been hearing this for a couple months now.

Anyone else experienced this and found the culprit?

Yozh · 01-26-2017, 02:25 AM

You will still hit full boost even with minor leaks, just depends on the conditions. May it's the turbo spooling down you are hearing?

torqueisking · 01-27-2017, 02:04 PM

Good to know so maybe it is a leak. Definitely sounds like air and not turbo spool. Time for hose-in-ear leak finding

torqueisking · 03-25-2017, 01:41 PM

Finally found a leak. Some of the turbo exhaust housing-to-cartridge bolts were loose enough to cause a leak. As soon as I took the small turbo heat shield off, exhaust residue on the underside of it and on the turbo housing was visible.

This also explains and resolves my periodic interior exhaust odour when stationary.

Butt dyno confirms a slight increase in power too

01-22-2017, 12:48 PM	#1
torqueisking Private First Class 46 Rep 141 Posts Drives: 335D Sport Join Date: Mar 2013 Location: Toronto iTrader: (0)	weird sound from engine with throttle release I'm hearing a sound from the engine bay which is like a vacuum cleaner powering down when I let off the throttle (from 50% or greater) in my X5 35D . Not 100% sure because it is subtle but it feels a bit slow and mileage seems worse but that could be the colder weather. I'm stock except for EGR block. I think it's an intake leak but I'm able to hit full boost as displayed by Torque and I can't find any leaks. Been hearing this for a couple months now. Anyone else experienced this and found the culprit?
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01-26-2017, 02:25 AM	#2
Yozh Colonel 881 Rep 2,611 Posts Drives: 2011 335d M-Sport Join Date: Mar 2014 Location: Wet Coast iTrader: (4)	You will still hit full boost even with minor leaks, just depends on the conditions. May it's the turbo spooling down you are hearing?
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01-27-2017, 02:04 PM	#3
torqueisking Private First Class 46 Rep 141 Posts Drives: 335D Sport Join Date: Mar 2013 Location: Toronto iTrader: (0)	Good to know so maybe it is a leak. Definitely sounds like air and not turbo spool. Time for hose-in-ear leak finding
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03-25-2017, 01:41 PM	#4
torqueisking Private First Class 46 Rep 141 Posts Drives: 335D Sport Join Date: Mar 2013 Location: Toronto iTrader: (0)	Solved Finally found a leak. Some of the turbo exhaust housing-to-cartridge bolts were loose enough to cause a leak. As soon as I took the small turbo heat shield off, exhaust residue on the underside of it and on the turbo housing was visible. This also explains and resolves my periodic interior exhaust odour when stationary. Butt dyno confirms a slight increase in power too
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