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Strange, long wooooo sound at steady speeds, ICE on


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226 replies to this topic

#1 OFFLINE   Alex Sams

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Posted 25 January 2014 - 11:52 PM

We took our first road trip in the C-max to see my parents. Along the way I noticed this intermittent sound that sounds like when you blow across the top of a glass jug to make a low woooooooooooo. I noticed that I could reproduce the sound by maintaining a steady speed with the engine on. When the vehicle ran in EV mode, I did not notice the sound. At first I thought it might be a bad bearing in the eCVT. Later I noticed that I could make the sound quit by turning off the recirculating air function in climate control. I could swear I heard it one time at 40 mph with the recirc off, but I'd have to do more testing to be sure. 

 

The sound was very loud, reverberating throughout the cabin of the car. It was louder than a normal speaking voice, so over 85 db. Does anyone know if this is a sign of not having a cabin air filter perhaps? I will check that as soon as I can tomorrow. I feel certain that there is something amiss in the cabin air intake system, but I'm unfamiliar with the vehicle. It could also have something to do with the tube that pipes air intake sounds into the cabin if this vehicle has one of those. 

 

Has anyone experienced anything like this?









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#2 ONLINE   ptjones

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Posted 26 January 2014 - 03:09 PM

We took our first road trip in the C-max to see my parents. Along the way I noticed this intermittent sound that sounds like when you blow across the top of a glass jug to make a low woooooooooooo. I noticed that I could reproduce the sound by maintaining a steady speed with the engine on. When the vehicle ran in EV mode, I did not notice the sound. At first I thought it might be a bad bearing in the eCVT. Later I noticed that I could make the sound quit by turning off the recirculating air function in climate control. I could swear I heard it one time at 40 mph with the recirc off, but I'd have to do more testing to be sure. 

 

The sound was very loud, reverberating throughout the cabin of the car. It was louder than a normal speaking voice, so over 85 db. Does anyone know if this is a sign of not having a cabin air filter perhaps? I will check that as soon as I can tomorrow. I feel certain that there is something amiss in the cabin air intake system, but I'm unfamiliar with the vehicle. It could also have something to do with the tube that pipes air intake sounds into the cabin if this vehicle has one of those. 

 

Has anyone experienced anything like this?

How many Miles do you have on the CMAX?

 

Paul


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#3 OFFLINE   Tdefny

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Posted 26 January 2014 - 03:19 PM

Could be a vacuum line. Has mileage been off?

#4 OFFLINE   Alex Sams

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Posted 26 January 2014 - 04:26 PM

Fuel economy was just under 40 on a highway trip. It's possible it could be vacuum related. I didn't think Ford was still using vacuum actuated flappers in the cabin air system. That would be a throwback, and it wouldn't make sense in a vehicle where the engine wasn't running all the time. 

 

We have 9300 on the C-Max. I can take it to the dealer since I can easily reproduce the sound, but I'm more worried about them breaking something else that I don't know about. I was hoping someone else had a similar experience. I'm going to investigate the cabin air filter situation first- make sure there is one in there, if not, see if that solves the problem. 



#5 OFFLINE   jdbob

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Posted 26 January 2014 - 04:43 PM

I didn't think Ford was still using vacuum actuated flappers in the cabin air system. That would be a throwback, and it wouldn't make sense in a vehicle where the engine wasn't running all the time. 

 

Ford is using stepper motors to control the cabin air system. 

 

hvacmotors.gif


Edited by jdbob, 26 January 2014 - 08:13 PM.

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#6 OFFLINE   mtb9153

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Posted 26 January 2014 - 07:13 PM

Are there complete wiring schematics available online somewhere?  I don't care to buy a shop manual since I find very little on this car I could even work on.  Plus I have two extended warranty's back to back to cover most repairs for awhile.


Edited by mtb9153, 26 January 2014 - 07:14 PM.


#7 OFFLINE   ScubaDadMiami

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Posted 26 January 2014 - 07:16 PM

Is it possible that you got something sucked into the air intake for the A/C?  Maybe try cleaning out the intake from leaves and debris?


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#8 OFFLINE   jdbob

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Posted 26 January 2014 - 08:10 PM

Are there complete wiring schematics available online somewhere?  I don't care to buy a shop manual since I find very little on this car I could even work on.  Plus I have two extended warranty's back to back to cover most repairs for awhile.

 

You can purchase a 72 hour, month, or yearly subscription to the workshop manual (which includes wiring diagrams) here: https://www.motorcra...ail/default.asp

 

However, it only works on Internet Explorer and requires a few other special programs be installed.



#9 ONLINE   ptjones

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Posted 26 January 2014 - 08:29 PM

I bought the CD and trying to figure it out how to use it.

paul

#10 OFFLINE   fotomoto

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Posted 26 January 2014 - 09:00 PM

Is it possible that you got something sucked into the air intake for the A/C?  Maybe try cleaning out the intake from leaves and debris?

 

I had a vehicle that quickly developed a reduction in fan performance.  It turned out that several napkins had been sucked out of the glove compartment while closed onto the fan's intake port.  


Edited by fotomoto, 26 January 2014 - 09:01 PM.

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#11 OFFLINE   FordService

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Posted 27 January 2014 - 03:14 PM

We took our first road trip in the C-max to see my parents. Along the way I noticed this intermittent sound that sounds like when you blow across the top of a glass jug to make a low woooooooooooo. I noticed that I could reproduce the sound by maintaining a steady speed with the engine on. When the vehicle ran in EV mode, I did not notice the sound. At first I thought it might be a bad bearing in the eCVT. Later I noticed that I could make the sound quit by turning off the recirculating air function in climate control. I could swear I heard it one time at 40 mph with the recirc off, but I'd have to do more testing to be sure. ...


Alex Sams,

 

Let me lend you a hand. PM me your name, phone number, VIN, mileage, and dealer info, and I'll take a look.

 

Ashley



#12 OFFLINE   joe

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Posted 27 January 2014 - 06:00 PM

I wonder if the sound suppression system within the cabin is malfunctioning and allowing you to hear a sound that normally would be suppressed.


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#13 OFFLINE   fotomoto

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Posted 27 January 2014 - 07:16 PM

I wonder if the sound suppression system within the cabin is malfunctioning and allowing you to hear a sound that normally would be suppressed.

 

I was thinking about this too and thinking that it maybe got out of phase so instead of canceling or reducing sounds it was enhancing the effect.  


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#14 OFFLINE   drdiesel1

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Posted 28 January 2014 - 01:21 AM

Could very well be "Exhaust Boom". At the right speeds and RPM's, the muffler/tailpipe can make sounds that can be heard

inside the cabin. My wife's Toyota Matrix does it @ 70 mph and only at 70 mph.



#15 OFFLINE   Tree63

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Posted 28 January 2014 - 10:24 AM

If it helps with sourcing it:  I've only heard anything like wooo-ooo for the first minute on really cold mornings (here in the great white north) when driving the car uphill. 



#16 OFFLINE   fbov

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Posted 28 January 2014 - 01:51 PM

I've heard something like this, but only over Thanksgiving, in Vermont after a little snow. It sounded a lot like a drivetrain moan (bearing?), but it came and went quickly, had no tactile component (couldn't feel it through the controls) and only occurred at a narrow range of speed, 40-50 mph. I concluded it was an odd acoustic resonance in the ventilation as I've yet to hear it in Rochester, or on other long trips.

 

Have fun,

Frank



#17 OFFLINE   Alex Sams

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Posted 28 January 2014 - 07:54 PM

II concluded it was an odd acoustic resonance in the ventilation as I've yet to hear it in Rochester, or on other long trips.

 

Have fun,

Frank

 

That's why I experimented to make sure I could re-create it. It happened at various speeds, but more so when the recirculation was on. I'm positive I can recreate the noise whenever I want to. That is essential in getting it figured out. I do think it's nothing serious- it goes away if I turn off the recirc. I don't know if Ford pipes the intake sounds into the cabin on this vehicle or not. If so, that could be part of the problem. I'll get it figured out eventually. FCS contacted me, and offered to contact my regional customer service manager. I might take them up on this because it might be something that they should know about to improve the vehicle. That's another reason I thought about asking others. 

 

You guys can try this to see if you can re-create my experience: Turn on the cabin air recirculation. Maintain a steady speed with the ICE on. It doesn't start immediately, but will get louder after 10 secs or so. Any change in throttle will cause it to disappear. Turning the recirc off will cause it to disappear. 


Edited by Alex Sams, 28 January 2014 - 07:54 PM.


#18 OFFLINE   fbov

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Posted 29 January 2014 - 11:21 AM

A repeatable problem is one you can investigate. Mine has't come back.

 

However, I've got suspects... look at these pics of Paul's car without the rear bumper cover. Note the louvres on an opening under the cover, below the tail lights.

 

Reading Hucho, he notes that interior ventilation will be speed dependent unless the vents are located in areas where the local air pressure is not speed-dependent. His example looks like Paul's car; vents behind and above the rear wheels. That leads me to suspect that we're seeing the interior exhaust vents in Paul's pics.

 

Now, a C-Max also has battery cooling, through vents in the interior, above these exterior vents, so I wouldn't be surprised if they exhaust better cooling air, too. If so, they form a Helmholtz resonator, similar to a ported subwoofer. The moan I hear would fit this phenomenon; I'll have to try recirc.

 

Have fun,

Frank


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#19 OFFLINE   Alex Sams

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Posted 30 January 2014 - 05:59 PM

Unfortunately, I don't get to drive my C-Max every day like the rest of you do. It belongs to the wife, I just pay for it. That's why I'm asking if anyone else can make the noise following my directions in case it's something built into the design that Ford might want to know about. We gotta give the QC engineers something to theorize about over Venti Latte's 



#20 OFFLINE   wab

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Posted 31 January 2014 - 12:15 AM

Alex

 

We traveled several thousand miles last summer with recirculate turned on (very few with it turned off) never a woooo.

Ford has gone to a lot of trouble keeping the noise level down in the C-Mac, don't think they would even consider bringing the under hood sound in (BMW).








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