Whistling sound at high revs and speed

LavosB

New Member
May 3, 2020
9
Hey guys! I have a e60 535i with the N54 engine and recently after doing the MHD backend flash with the JB4, I noticed a whistling noise coming from the left side of the engine bay ( if you sitting in the driver seat it’s left side), when I get over 80km/h and over 5000 rpms.

Does anyone know what it can be??
I suspect a boost leak but I’m not sure... maybe vacuum lines ?Thanks!
I have a JB4 tune with MHD, VRSF castles downpipes, DCIs from burger Motorsports,VRSF chargepipe with HK
 

NoQuarter

Captain
Nov 24, 2017
1,337
Indiana, USA
May just be window trim issue or similar.

Put some painters tape around the front windscreen and across the body seams and see if the whistle goes away.

Also, remove the DCI and put the air box in and see what happens with that.
 

fmorelli

Brigadier General
Staff member
Aug 11, 2017
2,882
Virginia
If you had a vacuum leak you could hear, your engine would be throwing codes. What other stuff has been touched or changed recently (last few months)? Is it possible that it has been there and you are noticing it now?

Filippo
 

LavosB

New Member
May 3, 2020
9
May just be window trim issue or similar.

Put some painters tape around the front windscreen and across the body seams and see if the whistle goes away.

Also, remove the DCI and put the air box in and see what happens with that.
No it ain’t that because I hear even when the windows are down , it’s definitely from the engine bay , from the intake side... could it be the HKS BOV?? Or the vacuum pipe? Maybe even the inlets ... but wouldn’t I get a code for a boost leak ? I’m so lost with , I’ll try putting the stock air box tho , thanks 🙏🏻
 

LavosB

New Member
May 3, 2020
9
If you had a vacuum leak you could hear, your engine would be throwing codes. What other stuff has been touched or changed recently (last few months)? Is it possible that it has been there and you are noticing it now?

Filippo
No I would have noticed it because it’s really loud and i noticed this morning it only happens on high boost so it must be boost leak but it’s weird I’m not getting any codes tho ... that’s why it’s driving me crazy cause it sounds like a boost leak but there is no codes 🤷🏼‍♂️ it literally started when I installed the MHD backend flash and it raised the boost a little bit more ... because once you install this backend flash with the jb4 all its maps boost limits are raised by a little bit more ... so something is not handling that boost raise that’s what I think , some plastic or rubber hose probably wearing itself out! I’ll try to keep a low boost and see if it still makes that noise if it does it’s definitely due to increase boost and some part not handling it 👍🏻
 

LavosB

New Member
May 3, 2020
9
If you had a vacuum leak you could hear, your engine would be throwing codes. What other stuff has been touched or changed recently (last few months)? Is it possible that it has been there and you are noticing it now?

Filippo
I have also been driving the car without the cabin filters and the engine beauty cover off .. could it be that ?
 

DCook

Corporal
May 25, 2018
236
Charge pipe
I have also been driving the car without the cabin filters and the engine beauty cover off .. could it be that ?
I wouldnt, id get a set of bms filters.

But, wind can whistle off objects, for instance the light bar on my pickup does above 70mph. Its just coincidence its 5k rpm for you? Maybe its whistling off something inside behind filterbox.

Or, you have a torn seal or leak on the bov and at 5k rpm its building boost and whistling and theres enough load at 80 its building boost to keep it at speed. It doesn't take much air to make a high pitch squeek/squeel to drop that much pressure to throw a code. Especially with an o-ring. Theres always stranger shit in the world to happen.

Shit maybe a friend put a harmonica on your bumper or turbo inlets. You never know! Like the good ole ziptie to the driveshaft.
 

LavosB

New Member
May 3, 2020
9
Charge pipe

I wouldnt, id get a set of bms filters.

But, wind can whistle off objects, for instance the light bar on my pickup does above 70mph. Its just coincidence its 5k rpm for you? Maybe its whistling off something inside behind filterbox.

Or, you have a torn seal or leak on the bov and at 5k rpm its building boost and whistling and theres enough load at 80 its building boost to keep it at speed. It doesn't take much air to make a high pitch squeek/squeel to drop that much pressure to throw a code. Especially with an o-ring. Theres always stranger shit in the world to happen.

Shit maybe a friend put a harmonica on your bumper or turbo inlets. You never know! Like the good ole ziptie to the driveshaft.
Ahahahah that would be funny 😂
 
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