My car is making a moderately loud, irritating whining noise which appears to be coming from the upper intake manifold area. It is never there on cold start but once the car has warmed up it happens with 100% frequency. It is by far most noticeable at idle or low speeds but it doesn't change in pitch or tone with load or RPMs so it's not the belt or pulleys. I have also ruled out the air pump which I hear making its normal noise during the first minute or so of cold startup, the whine doesn't start immediately after the air pump goes off either. Vacuum appears to within the normal range at cold startup and when warm based on the other recent thread where people posted their vacuum readings.

I'm not sure when the noise began exactly, it used to sing from the intake filter with a similar pitch when I installed the AEM intake. Once the turbo was installed the sound is definitely not coming from the filter though, I narrowed the area down using both with the screwdriver to ear method and a paper towel roll.

I took two recordings of the noise. The first is while it is running, the first 40 seconds are under the engine bay hovering the camera around the general area then after 40 seconds I get the car. The second is the sound it makes when turning off the car as it tapers off and raises in pitch a bit (ignore the turbo timer beeps).

Megaupload (requires 45 second wait but quicker speeds):
Running
Shutdown

Sendspace (no waiting, just look for the download link on the linked page):
Running
Shutdown

 

Check your OMP vent and Jet-Air hose circuits.

 

The site you used said I couldn't download right now

I know that my one-way-check-valves make a whining sound...
maybe you have a vacuum leak as well

before you ask...

 

Throttle stepper motor.

 

You should be able to hear this with the key on/motor off

 

Thanks for the assistance everyone

I've updated the links in the original post to use sendspace so you don't have to wait 45 seconds to download (still cannot right click save as though, sorry).

The sound doesn't happen with the engine is off but key is in the on position. I will investigate the issue further with the recommendations made here.

 

Yeah. True.
I kinda skimmed when the video threads didn't work.

 

sounds a little like mine (but a LOT louder ) .

Mine comes from the turbo ......

atually - scratch that . I USED to have a very similar noise before I discovered a vac. leak just before the turbo . Now gone .

So - there's a clue .....

 

Any resolution to this? I've had the same sounding whine that you've had in your "shutdown" recording for several months now. Haven't had much luck tracking it down. I know a guy that has a smoke machine at his local shop. I'm thinking I'll have him hook it up and see if I have a vacuum leak.

 

I haven't had much free time to work on the car in the past few weeks so no updates yet, the sub 30 degree temps are not a great motivator either... I am going to install some new P2 injectors at some point in the near future so I was going to do some testing around when I have the UIM off.

If you find anything out please post the results

 

Will do. I'm going to go by the shop on Wednesday to get the intake smoked. Figure that's easier than trying to track it down myself in this cold weather

 

Sorry to bump! Seems like this isn't a common problem. My 2004 sounds exactly like the sound clips above. Was wondering if a solution was ever found for this ear wrenching sound. I'm trying to avoid a 6 hour service bill from Mazda with no solution and I don't know where else to take the car in my area! Please reply!

 

The jet air mixing tube thingy on the back of the lower intake manifold was disconnected. We put it back on and it hasn't made a sound since.

 

My suspicion is that any number of vacuum leaks could cause this same sound. I would recommend taking it to a shop with a smoke machine and having the intake smoked.

 

Could you please explain the location of the jet air mixing tube and the best way to access it. Had the car up on a hoist and couldn't see s@#t!!

 

here :

 

Well I found it. Looks like it's definitely disconnected. Could I get at this by pulling the alternator or am I going to have to remove the upper intake?

 

I didn't actually reconnect mine, but my buddy was able to get his hand back there reaching over the top of the UIM and reconnect it. But I don't have a stock upper intake manifold, so I'm not sure if you can get to it with that in place or not.