Whistle at low throttle?

[brian75x]

I have an odd "whistle" noise at low throttle. It is not present at idle (zero throttle) or at any throttle over, say 15%. It only occurs when driving leisurely with light throttle pressure (like up a very slight grade at 25mph).

It is high-pitched. The pitch does not vary with RPM's. It just starts with a little throttle pressure and goes away if you let off pressure or give a little more pressure.

I do not think it is a squeak or squeal, it is more of a whistle as if produced by air, not metal or rubber.
NO check engine light.
It sounds like it is from engine compartment, not chassis.

Ideas?

[kayger12]

My money is on a torn lower intake boot.

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[Matt]

Have a look at your lower intake boot, as seen in Topic #9 HERE (http://www.bmwmafia.com/forums/showthread.php?27-BMWMafia-s-Official-E46-Preventative-maintenance-Issues-DIY-s) and the DIY to fix it HERE (http://www.zhpmafia.com/forums/showthread.php?1536-BMW-E46-Upper-and-lower-intake-boot-removal-DISA-inspection)

[adb1028]

Definitely your lower intake boot. I had the same problem a few months ago and that solved the problem. Mine was all dried up and had a few nice sized cracks in it. Its a somewhat easy DIY, but its a real pain getting the metal clamps off since the screws are facing backwards. I would replace your upper boot too (which I wish I did at the time).

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[zhpnsnv]

Dealer just quoted my friend $415 for a lower intake boot. It's something like a $20 part. Hahahaa


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[kayger12]

Dealer just quoted my friend $415 for a lower intake boot. It's something like a $20 part. Hahahaa


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Stealers, FTL.

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[danewilson77]

What about the lower intake boot? Hehe

Also...gasket around the disa, or upper intake boot could be culprits....

Also...check codes anyways....as they can be stored and not represented by a light......if you have a reader...

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[aurelius]

I have an odd "whistle" noise at low throttle...

Ideas?

How many miles on your car?

[Crickett]

+1 more on the lower intake boot; I had mine go a few years ago.


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[brian75x]

How many miles on your car?

Just over 58,000 miles on it.

[kayger12]

Seems kind of early for an intake boot, no?

Anybody have one go that early?

[Mtnman]

It is low miles but being a rubber, non moving part, I would think age of car would mean more than number of miles on this particular part.....

[kayger12]

It is low miles but being a rubber, non moving part, I would think age of car would mean more than number of miles on this particular part.....

Makes sense, David. Good point.

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[adb1028]

Seems kind of early for an intake boot, no?

Anybody have one go that early?

Mine was toast at 59k. Had a nice long tear in the skinny upper part.

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[kayger12]

Mine was toast at 59k. Had a nice long tear in the skinny upper part.

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Gotcha. Cracks me up- the quality (or lack thereof) of some of the pieces they put in this car.

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[Crickett]

Mne went around 4.5 years & 54.5k miles.

[danewilson77]

Mine...in the TiAg lasted 8 years....

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[adb1028]

This is what your looking for:
http://tapatalk.com/mu/aeff795b-6d2b-0317.jpg

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[MasterC17]

By the way if you have an AFE Intake you'll probably get this noise whether the intake boot is torn or not. Or at least I do.

[mimalmo]

By the way if you have an AFE Intake you'll probably get this noise whether the intake boot is torn or not. Or at least I do.

Yes, aftermarket intakes make the intake whistle audible. The OEM airbox shouldn't make any such noises.

[Jesse M]

Lower intake boot for sure. Mine cracked on the small flexible house and you described it exactly how I did. I should be getting mine in today and I will post results.

[Dean]

I dont think it is the lower intake boot at all. I installed a K&N replacement air filter into my OEM air box, and immediately after I experience the same whistle. You should check and see if the previous owner (or maybe you) installed a different than OEM filter. I think the aftermarket filters just whistle a bit. Only reason I don't think it is the intake boot, is the milage of the car...fairly low for those kind of issues it seems?

[danewilson77]

Lower intake boot for sure. Mine cracked on the small flexible house and you described it exactly how I did. I should be getting mine in today and I will post results.


I dont think it is the lower intake boot at all. I installed a K&N replacement air filter into my OEM air box, and immediately after I experience the same whistle. You should check and see if the previous owner (or maybe you) installed a different than OEM filter. I think the aftermarket filters just whistle a bit. Only reason I don't think it is the intake boot, is the milage of the car...fairly low for those kind of issues it seems?

Check both.....

Boot crack should throw a code.....filter element would not...

[Dean]

Check both.....

Boot crack should throw a code.....filter element would not...

A resolution was finally made, and the constitution of the United States of America was born.

signed,


Dane Wilson.

[danewilson77]

A resolution was finally made, and the constitution of the United States of America was born.

signed,


Dane Wilson.

:rofl

Just sayin......dhu eeeeeet.

[Jesse M]

-- Confirmed. Sound is gone, no CEL.

[Jesse M]

Only reason I don't think it is the intake boot, is the milage of the car...fairly low for those kind of issues it seems?

You'd be surprised .. I have 96k, I noticed it ever since I bought it at 82k but I thought it was just one of those 'maybe it's supposed to do that' kind of things. Can't hurt to check it out, just stick your hand down there and feel around the hose..

[quikryptonite]

I just had this "whistle" develop in my E30 yesterday, I'll check the lower intake boot today after work.

[llll1l1ll]

I have the same sound. I thought it was actually part of my drive-by-wire throttle lol. All this dag gumb newfangled tek-naw-low-gee!

Turns out I found a small, paperclip-sized crack in my lower boot. I'll go ahead and replace it to see if that solves it.

[danewilson77]

I have the same sound. I thought it was actually part of my drive-by-wire throttle lol. All this dag gumb newfangled tek-naw-low-gee!

Turns out I found a small, paperclip-sized crack in my lower boot. I'll go ahead and replace it to see if that solves it.

I would bet it does.

[Taliben]

I'm having the same issue I guess. But i just installed an afe intake and it became really apparent. Plus I'm throwing a P0171 and a P0174 code which means its running a bit lean. Any clues?

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[danewilson77]

Intake boots. Check disa, and icv while you're in there. Could possible eliminate issues down the road.

If it got worse, after the intake either one of two things is going on.

1. Maybe one connection isn't made up quite right.

2. The intake could be exaggerating the original issue due to "different" air flow.

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[quikryptonite]

I have the same sound. I thought it was actually part of my drive-by-wire throttle lol. All this dag gumb newfangled tek-naw-low-gee!

Turns out I found a small, paperclip-sized crack in my lower boot. I'll go ahead and replace it to see if that solves it.
Ha ha,
Dag gumb reminds me of this lately:
http://www.youtube.com/watch?v=arUunVhLG_0

[llll1l1ll]

My CEL has been on for a while. I went to Advance Auto to get it checked out and the car is throwing the lean codes. So, it probably is that tear in the boot!

[johnnyrad]

My 02 xi has the whistle. Got this morning driving to work I was like WTF is that noise. It was the most annoying sound. Like a high pitch whistle. By the ride home from work it was seriously making me angry. But the performance of the car hasn't changed and no warning lights either. Well had the car for a week and on the coldest morning of the year out she comes. I'm going to replace the lower boot but is the DISA gasket a tough job?? Or should I replace the whole DISA? Can't tell if it was ever done.

[danewilson77]

DISA is very easy Johnny.

The disa gasket is integral to the disa, so you can't change it. What I did was put a thin skimming of non hardening Permatex on it. Also on the frame gasket area's as well.

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[johnnyrad]

^Thanks for the confidence DW. I will ad it to the list. I reckon I'm going to spend about a grand in parts including the CV axle work before my XI is at the spot it needs to be. But I sorta figured between five hundred to a grand anyway. I think my ZHP is getting lonely and jealous as I'm spending all my time on the other one. hehe

[johnnyrad]

Dane in your opinion, by changing out the DISA and both boots the problem should go away? Funny thing is, yesterday I took out the air box just to clean the MAF sensor and clean up all the dust on the box and poke around, put it all back and didn't drive it. This morning as soon as I hit the open road the whistle was there. So I'm wondering if I stirred something up.

[johnnyrad]

What I did was put a thin skimming of non hardening Permatex on it

An epoxy or sealant or some kind? What exactly should I use?

[kayger12]

I would recheck the intake box and make sure you have it buttoned up properly.

I'm thinking you have something slightly out of alignment/not connected properly.

I would start with inspecting/replacing the lower boot first.

I don't think the DISA gasket would develop an issue that bad out of the blue like that.

To seal the DISA (if you decide to do that) you can use RTV sealant.

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[danewilson77]

I would recheck the intake box and make sure you have it buttoned up properly.

I'm thinking you have something slightly out of alignment/not connected properly.

I would start with inspecting/replacing the lower boot first.

I don't think the DISA gasket would develop an issue that bad out of the blue like that.

To seal the DISA (if you decide to do that) you can use RTV sealant.

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+1

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[johnnyrad]

Well I sorta already ordered the DISA and both boots..er ah don't tell the wife hehe..SO here is what my Saturday and Sunday morning looks like. Replace drive and ac belts, water pump pulley, expansion tank, DISA, both intake boots, coolant flush, both front and rear diff flush, transfer case flush, toilet flush and anything else that flushes..can't wait.

[danewilson77]

Well I sorta already ordered the DISA and both boots..er ah don't tell the wife hehe..SO here is what my Saturday and Sunday morning looks like. Replace drive and ac belts, water pump pulley, expansion tank, DISA, both intake boots, coolant flush, both front and rear diff flush, transfer case flush, toilet flush and anything else that flushes..can't wait.

If the DISA doesn't fix.... Pull it back out, and save as a spare. Money is not lost.

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[johnnyrad]

Good point Dane, I'm sure I'll need it later on. I just hope the hell that whistle goes away. I read on e46 Fan. that another idea for the whistle might be a vacuum hose? Not sure tho. Any thoughts on that?

[danewilson77]

Good point Dane, I'm sure I'll need it later on. I just hope the hell that whistle goes away. I read on e46 Fan. that another idea for the whistle might be a vacuum hose? Not sure tho. Any thoughts on that?

Yeah... You could end up chasing a bunch of stuff in the CCV system, but i would think you would have an SES light.

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[johnnyrad]

Yeah no light yet. I just don't get how for a week the car made no whistle and all of a sudden it started and gawd is it annoying.

[llll1l1ll]

My whistle was caused by a q-tip sized hole in the elbow of the lower intake boot. Only at certain throttle positions would it whistle. Whistle was gone once I replaced both the boots.

However, that uncovered a large sucking sound. I'm not sure if that's just because the car's engine sucks in a lot of air, or there is a loose vacuum hose. The latter is the likely culprit. Granted, my car doesn't act like it has a vacuum leak, and the mechanics mentioned nothing about any abnormal sucking sounds. Granted, I did not bring the issue up as I was there for VANOS.

Anyway, make sure everything is buttoned up - particularly the connection between the lower intake boot and the throttle body. It's the biggest PITA to work down there, and my first attempt at the job left my lower intake boot just hanging by the elbow hose to the ICV. This resulted in many unanticipated engine stalls when taking right turns.

[danewilson77]

I think you would have SES light/Codes/Performance issues if you had a large leak.

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[llll1l1ll]

As was the case with my car, since the pinhole leak caused the SES light to come on for running too lean on both banks.

It's been about three weeks and almost 1K miles since I turned the SES light off. It hasn't came back! Methinks there is no vacuum leaks.

[johnnyrad]

Well I just replaced the lower intake boot. What a mother f**ker bleep bleep that was. Two and half hours it took.. I managed to the snap off the tiny little hose connection to that "F" fitting on the upper boot. Not happy, ordered one of those. And I think the hardest part was re-installing that clip for the sensor on the DISA. Could they make it any more difficult? The DISA seemed ok but the inside had caked on grease or dirt or something on it, so I wiped that down. So no holes in the lower or upper boot but since I took a utility knife to the lower one I replaced it anyways. Took it for a test drive and the "whistle" is still there :scratchinghead. I have a DISA on it's way so I will put the new one in on Saturday to see if that works. I don't get it, just don't get it.

[danewilson77]

Ugh. This is looking more and more like a.....

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[johnnyrad]

Ugh. This is looking more and more like a.....

yes go on..

[johnnyrad]

Ya know I'm thinking it's the DISA. Because when I took it out, it looked like the original and the little pin at the tip that hold the flap in place was loose, so of course I pushed it back in. And I read that it will give off a clicking sound when it's going bad, and I keep referring to a whistle. It kinda is like a click mixed with sort of a whistle..IDK I guess I'll find out, after inspecting though I could see it making the sound I was hearing. If that's not it I'm going to bang my head into a wall I think. :)

[spencers]

Ya know I'm thinking it's the DISA. Because when I took it out, it looked like the original and the little pin at the tip that hold the flap in place was loose, so of course I pushed it back in. And I read that it will give off a clicking sound when it's going bad, and I keep referring to a whistle. It kinda is like a click mixed with sort of a whistle..IDK I guess I'll find out, after inspecting though I could see it making the sound I was hearing. If that's not it I'm going to bang my head into a wall I think. :)

Is it happening at certain RPM's?

I'm currently chasing an extremely high-pitched annoying whistle myself. Only happens at/near freezing temperatures, at exactly 2100rpm. Goes away when the car is fully warmed up.

I chased it last year during winter. Changed both intake boots as well as the CCV & hoses. None of which fixed it. Then the weather got warm again and I completely forgot about the whistle.

There's an ongoing thread at E46fan with a guy that has the same exact problem with his 330ci. He's thinking alternator. I'm going to change my idler/tensioner pulleys (highly doubt that's the source). :dunno

[johnnyrad]

Mine started on the coldest morning of the year (this past Monday) Spencers. It doesn't happen at idle, only when I'm rolling. I haven't noticed it at a specific rev range though. It's not my boots, I eliminated that last night. It does not go away when my car is warmed up. It does stop however if I shift into neutral when I'm driving. It stops immediately, like it's connected to my gas pedal or something. It only happens when I'm in gear. I'm currently in chase mode with this thing, and I'm going to win. I will find it if I have to replace every damn part on car..ugh

[strz0001]

When it's moderately cold, my emission control air pump howls a bit. This pump supplies the cool exhaust system a blast of fresh air to rapidly heat up the cats so they operate efficiently sooner. If the noise goes away after it warms up, that might be the culprit if the vacuum system is intact.

#1 in the diagram below.

http://www.realoem.com/bmw/diagrams/f/b/206.png

[spencers]

When it's moderately cold, my emission control air pump howls a bit. This pump supplies the cool exhaust system a blast of fresh air to rapidly heat up the cats so they operate efficiently sooner. If the noise goes away after it warms up, that might be the culprit if the vacuum system is intact

The SAP only stays on for 1-2 minutes after initially starting the car. Whistle still occurs after the SAP turns off. Whistle goes away after the car reaches operating temperature. I can't speak for others, but that's just me.

[danewilson77]

When I was actually doing research on my car...I ran across a thread where a fella had a break at the flange (where 17 is pointing, above) and was creating a vaccum leak of sorts.

[johnnyrad]

Think I found it. Me thinks it's the belt tensioner for the alternater. I took off the belt to check it and she spins and spins and spins freely for..well ever. It's totally shot it even has some play in and out on it, it looks original. Original with 120k on it. Ouch. Either way it needs to be replaced asap. I think it's the hydraulic one not the mechanical one. But the car is a 2002.

Edit: I should say the bearings in the pulley sound shot, their loud and sound like they need grease or something.

[spencers]

Think I found it. Me thinks it's the belt tensioner for the alternater. I took off the belt to check it and she spins and spins and spins freely for..well ever. It's totally shot it even has some play in and out on it, it looks original. Original with 120k on it. Ouch. Either way it needs to be replaced asap. I think it's the hydraulic one not the mechanical one. But the car is a 2002.

Edit: I should say the bearings in the pulley sound shot, their loud and sound like they need grease or something.

Hopefully that's the source of the whistle.
Regardless, it sounds like the pulley does need to be changed.

[johnnyrad]

YES !!! It was the pulley's Jerry! The pulleys! ha ha ha oh man am I grateful that's all it was. Man those things were shot to shit. I just got back from a test drive and all I heard was the smooth hum of the M54..how sweet that truly is. I replaced all 5 pulleys and drive belt (as I did the ac belt last weekend) and installed a new OEM air filter and she now drives like she should. I installed the ECS water pump pulley that they say is 7% smaller so wondering if I will see any kind of change in mileage or quickness idk, it looks nice though.
I really listened to the sound today prior to working on it, and I should say it wasn't really a whistle, it sounded more like a jet engine but quiet. You know when you find yourself watching Top Gun some rainy evening at 10pm and the F14's are fired up on the carrier, that's what it sounded like. And the noise was in sync with my gear changes. In between shifts, the noise would lesson and as I hit the gas the noise would worsen. Makes sense really.

I love my cars.

[kayger12]

Glad you solved it.

Good job.

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[johnnyrad]

Thanks Keith. Feels good. Love it when a plan comes together. Now all I need to do now is tacke the CV Boot replace and diff and transfer case fluid change and I'm caught up.
Snow coming tomorrow and the XI will be ready.

[danewilson77]

YES !!! It was the pulley's Jerry! The pulleys! ha ha ha oh man am I grateful that's all it was. Man those things were shot to shit. I just got back from a test drive and all I heard was the smooth hum of the M54..how sweet that truly is. I replaced all 5 pulleys....??

I love my cars.

Well done.

1. AC tensioner pulley.
2. Serpentine tensioner pulley.
3. Deflection pulley.
4. Water Pump pulley.
5. ?????? > PS pulley?

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[spencers]

I can tentatively say I've solved my whistle.

As I said prior, I had a whistle at 2100rpm when the outside temperature is at/below freezing. Always went away when the car warmed up. Replacing the lower intake boot and CCV last winter did not solve it. Replacing the tensioner pulleys and idler did not solve it this year.

I replaced the alternator this morning. Bosch remanufactured. Removal of the old alternator was pretty simple. Took some prying to get the old one out.
Installing the new one took some leverage to get the bottom bolt threaded on. Otherwise, easy!
http://img692.imageshack.us/img692/5012/img0519mr.jpg

Here's a video of the old alternator. Almost certain this is where the whistle was coming from!

http://www.youtube.com/watch?v=UGQfDiRf-Uw

[johnnyrad]

Well done.

1. AC tensioner pulley.
2. Serpentine tensioner pulley.
3. Deflection pulley.
4. Water Pump pulley.
5. ?????? > PS pulley?

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You are correct Dane. Power steering pulley was the fifth one. It was fine, but I upgraded to the aluminum one.

[johnnyrad]

I can tentatively say I've solved my whistle.

As I said prior, I had a whistle at 2100rpm when the outside temperature is at/below freezing. Always went away when the car warmed up. Replacing the lower intake boot and CCV last winter did not solve it. Replacing the tensioner pulleys and idler did not solve it this year.

I replaced the alternator this morning. Bosch remanufactured. Removal of the old alternator was pretty simple. Took some prying to get the old one out.
Installing the new one took some leverage to get the bottom bolt threaded on. Otherwise, easy!
http://img692.imageshack.us/img692/5012/img0519mr.jpg

Here's a video of the old alternator. Almost certain this is where the whistle was coming from!

http://www.youtube.com/watch?v=UGQfDiRf-Uw

Nice work brutha. Man that sounded horrible. How many hours did it take you?

[spencers]

Nice work brutha. Man that sounded horrible. How many hours did it take you?

Took around 45 minutes. An hour tops. :)

[johnnyrad]

Nice win right there!

[danewilson77]

Sounds hideous.

[spencers]

25 degrees this morning and the whistle is GONE!

I can finally drive at ease knowing I've finally solved this stupid noise!!!!

[NorCalZman]

I am so glad I found this thread and hopefully I will have my sanity back when cruising on the freeway. I have this annoying whine that happens only when I am driving and from 10-15% throttle. Above or below that it immediately goes away. No codes or anything. Just the whine. I thought it sounded electronic in nature and couldnt tell where it was coming from, but it sounds like others have solved this with new intake boots. I am kind of surprised I can hear it on the freeway if its a tiny air leak but whatever.

I will order the new upper and lower intake boots, F connector, and DISA (what the hell) immediately.

http://www.bmw330ci.net/maintenance/tubeelbow.php