2016 CX-9 Turbo Whistle

MrAbracadabra

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2016 Mazda CX-9 GT
Just hit 40k on my 2016 CX-9 so I did the spark plugs and and engine air filter replacement.

Now Im hearing the turbo make noise and whistle at every acceleration and especially when I let off the gas. Could a clean new air filter cause this? Or is something else going on and its just a coincidence it present itself after I did some maintenance?
 
Is the air filter element correctly seated and the air box cover correctly seated and latched down? A leak in the air box cover seems like a likely source of the whistling sound. Maybe a loosened connecting hose to the air box?
 
Old one was dirty, that*s for sure. I might change this one sooner.

Dropped it off at the dealership tonight, they will get to it in the morning. There was a recall I put off last time so I decided to do that and ask them to take a look at the turbo.

The service advisor double checked the filter, which was seated and latched properly. What was interesting is the loaner I got was a 2018 CX-9 with 4K miles.

Turbo sounded just like mine, so what I was hearing was probably a result of the new clean filter. They said they would give it a once over anyway but reassuring to hear same thing from a nearly brand new loner. Guess I wasn*t used to hearing it with a dirty filter.
 
Yep, If I drive it hard (which I do *sometimes*) and turn off the music, I can hear the turbo spool up. (iagree) Kinda wish it was louder too!
 
Just hit 40k on my 2016 CX-9 so I did the spark plugs and and engine air filter replacement.

Now I*m hearing the turbo make noise and whistle at every acceleration and especially when I let off the gas. Could a clean new air filter cause this? Or is something else going on and it*s just a coincidence it present itself after I did some maintenance?

Did you find out what's causing the whistling noise? If not, try lifting the engine air filter cover. If you can easily lift it, then that's the culprit. The cover is not seating properly on it's base even if you had snapped the 2 locks up front.
 
It ended up being normal. I had a loaner while it was in for service, a brand new 2018 CX-9 and it was doing the same thing. I*m chalking it up to a new filter and me not remembering it was normal with a clean filter. I think I will be changing it a little more often than the 37,500 recommended. I feel like I may be getting slightly better MPG now too.
 
You should definitely change the air filter sooner than that as dirty air filters are not good for turbos. I realize that I have a different turbo but it always had whistle sound and its still good @149K. Had another Mazda with a 216K original turbo miles that you could also hear. Your cabins are quieter. I wonder if these current maintenance recs are designed to generate replacement part revenues?
 
It ended up being normal. I had a loaner while it was in for service, a brand new 2018 CX-9 and it was doing the same thing. I*m chalking it up to a new filter and me not remembering it was normal with a clean filter. I think I will be changing it a little more often than the 37,500 recommended. I feel like I may be getting slightly better MPG now too.

I just bought a brand new CX9 and it has the same whistle. I had a loaner 18 mazda 6 that had the same thing. I am glad I found this tread that also confirms it is normal noise. Its very low, my wife cant even hear it.
 
Just hit 40k on my 2016 CX-9 so I did the spark plugs and and engine air filter replacement.

Now Im hearing the turbo make noise and whistle at every acceleration and especially when I let off the gas. Could a clean new air filter cause this? Or is something else going on and its just a coincidence it present itself after I did some maintenance?

Is there a photo of a spark plug? I want to find some better alternatives.
 
The cleanliness of the air filter does not relate to fuel efficiency on modern (since the '80s) computer controlled engines. The mass air flow sensor signals to the engine control unit to only inject as much fuel as that much air can burn properly. A dirty, high resistance air filter might cause a loss of top end, full throttle, high rpm power, but it can't affect fuel efficiency. And, anyone who says that a so-called high performance air filter increases power doesn't know how the engine control system works.

A dirty air filter harmful to a turbocharger? Not unless it leaks dirt through it. A dirty air filter with high resistance acts exactly like a throttle butterfly that doesn't quite fully open.

Could the whistle mentioned actually be the normal sound of air flowing through a clean air filter? We gradually get used to a different sound as the air filter in service slowly accumulates dirt.
 
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