Car whistling upon acceleration, as if there's an air leak.

[thinkpad240]

First thing in the morning or late at night at 80F, or while accelerating, the car decides to make a whistiling (howl) sound as I accelerate even to 20 mph. The howling gets louder as speeds pick up but the RPM is consistent even at freeway speeds. It just been acting up this way noticeable 3 weeks ago and it should not be making this noise on a cold engine or even driving in the first 30 minutes. I've already put a new Oring in the DISA and clean out the MAF with a spray can a few months ago before this howling started , and I can't find any leaks in any of the hoses.

I plan to put in a new air filter early next week but I've already looked into it today to see if anything was obstructing that assembly. Found nothing.

Any ideas? I'm going to have it looked at by my local BMW shop soon.

[Newjack]

Any codes?

[holyc0w]

Vacuum caps?

[thinkpad240]

Vacuum caps?

Never seen one but which vacuum cap(s) are you referring to? Also my Peake code reader found no codes the other day.

[holyc0w]

Never seen one but which vacuum cap(s) are you referring to? Also my Peake code reader found no codes the other day.

There are three at the back of the engine on the driver's side. One is 7mm (11611727176) and 2 are smaller (11611437560).

[Newjack]

Let me hit you with some knowledge fam

https://youtu.be/3encrkBsss0?t=643

[Dave1027]

The caps are on the back side of the intake manifold. Near the firewall. Hard to see them. You need to go by feel.
It's like this pic but I don't think our cars have the hose as shown. Our's have all three capped.
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[holyc0w]

The caps are on the back side of the intake manifold. Near the firewall. Hard to see them. You need to go by feel.
It's like this pic but I don't think our cars have the hose as shown. Our's have all three capped.


I missed the link I was going to post. Yeah from what I felt there was no hose there. I changed the 7mm as it felt pretty cracked. I didn't get a chance to see it as it flew off somewhere when I took it off. The smaller ones were pretty difficult to take off by hand. I could not do it, but they felt like they were in better condition. But it's probably a good idea to change those too.

[thinkpad240]

Thanks guys. I will go check these out this week.

[thinkpad240]

I learned that this is not an air leak. The fan clutch is broken and was replaced . That solved the howling noise.