Noise from intake after switching off..?
 

Hi All have a strange noise coming from engine bay after I switch the ignition off.
Sounds like it may be around the intake manifold and sounds like a small motor turning or something. Only happens when ignition is turned off-any thoughts?

No CEL
Havent noticed any drivability issues

Update-06/12/2009

Problem found-its the actuall stepper motor for the APV valves on the side of the intake manifold
Charles and Jon thanks for all the help.

You might be hearing the throttle valve cycling closed against the throttle positioning sensor to learn its position, then opening 5 degrees which is its idle position.

Thanks-was about to PM you..lol

Ok but is that safe that it sounds like a small electric motor every time I shut the ignition off?
Never used to do this before and just started recently.
Iv been reading all the posts about the ssv and was wondering if it wasnt perhaps that.

The throttle valve is driven by an electric stepper motor, so yes its safe to hear that sound.
Its possible that build-up on the valve is working the motor harder and increasing the sound it normally makes.
Take off the flexible intake tube and open the valve by hand.
Clean the valve the best you can and see if the sound continues.

Maybe before turning it off, open the hood and stand by the engine bay while someone else turns the car off.
This way you can narrow down where the sound is coming from... may not be the throttle valve.

I doubt it... it wouldn't make a "motor sound" since the actuator is driven by vacuum.
Not to mention the SSV is already closed at idle.

Well funny enough I was in there earlier as I just installed the BHR KIT as well as the throttle bypass mod as it gets extremely hot here-I gave the throttle body a good cleaning-wasnt that dirty though-and the sound seems to be coming from where the intake joins the motor itself-close to the air pump actuator I think.

The APV motor cycles after you turn off the ignition to free-up any carbon build-up.
Does it sound like its coming from underneath the air pump?

more or less around that area I wont say under the air pump exactly-more so under the intake manifold or close to that area. hence my assumption that it was the ssv but your explanation killed that theory..thank goodness!!!

heres a pic of whereabout the sound seems to be coming from.

Yes its from one of your posts...iv been doing a lot of searching but found nothing on this hence my thread.

The APV is just to the left (and slightly down) from the SSV... so it could still be that.
And the APV is controlled by a stepper motor. Hard to say for sure.

Might be easier to get a video clip of what you're experiencing.
This way we can tell if its an electric motor sound or a rapid tapping sound.

Just remember, when the engine is turned off there is no vacuum to open the SSV or VDI so this is another reason I doubt its the SSV.
This is why the APV is driven by an electric motor instead of vacuum like the others.
Because Mazda wanted the APV to cycle when the motor was off.

Definitely an electric motor sound-will check the apv. could be that.
how exactly does it operate to clean carbon build up?
Any advice on checking it?

it's the APV - you get cool sounds like that for free

Simple... it cycles the valves back and forth whenever the ignition is turned off.

This is the tricky part...
To remove the motor you need to remove the front passenger-side tire.
Then remove the hard pipe for the ACV bolted just above the exhaust manifold.
And that hard pipe is held on by a bolt under the ACV just above the thermostat.
With those out of the way you can remove the two bolts securing the motor.

You can use a basic 12VDC transformer from an old telephone or other electrical device you don't use anymore.
It'll be easier to show you this video I made for testing the intake valves:
http://www.vimeo.com/5353829

Now since the motor can be tricky to remove if you've never done it before, you can just leave the motor in there, disconnect the wire harness, and apply the 12V to the motor.

why are you telling him all this - it makes the noise and he has no drivability issues ---------- therefore it is operating correctly .

Not necessarily true...
A motor that is strained will make a louder sound.
Meaning... if carbon is built-up on the valves enough to strain the motor, its not operating "correctly".
Carbon issues on valves are more noticeable as the climate gets colder.
Its getting colder outside, he mentioned just now noticing the sound... I don't see what your problem is.

NVM sorry if that came across as a criticism .

It did... but as you know its difficult to tell someone's response from just typed text without our lovely "smilies" to express the response.
I appreciate you clarifying it for me :)

It makes sense that the noise will be a result of more stress-what will the result of me running current to the motor be?

When you say it cycles the valves which valves are you reffering to?
Im assuming running current to the motor will turn the valves resulting in it removing excess carbon..?

Excuse all the q's just trying to understand as much as possible and its my first time experiencing this issue.

The APV valves\barrels on the intake.
The motor is attached to a rack and linkage setup as you can see in the video linked above.

So in essence I have carbon build up on the valves resulting in the apv having to work harder to cycle them? Hence the louder sound it makes upon switching the ignition off.


Im assuming I will have to make it cycle a few times in order to clean the carbon?
Whats the process when running current to the motor?
Thanks for the advice Jon.
Will watch the video once I have a better internet connection

That is my guess... again, I could be wrong about it being the APV motor making the sound... just can't think of what else it could be around that area at that time.

I use a regular 12VDC transformer from an old electronic device like a telephone to convert the 120V from the house to 12VDC needed for the motor.
And the amps are usually pretty small and won't harm the motor.

wow just watched your vid - good job man .


Highly unlikely the OP has an issue from what he has said though . Probably just that he had not noticed the noise before .....

Appreciate the compliment Brettus

Its very possible.

Well now I have issues!!!!!
The car limits at 7000rpm and just bogs down if I stay on the gas...wtf..Is this some sort of safe mode the car is going into?
Any possibilty this is linked to the noise?
Cant be the cat-I dont have one
Cant be coils-just installed the new BHR kit.
No engine light either.

Any advice?

The APV doesn't attempt to start opening until 6250RPM, but what you describe sounds like the car went into limp mode.
Sucks that you don't have a CEL because of this, but you could always scan for codes that may be pending (basically waiting for the same thing to fail a 2nd time before it actually illuminates a CEL).
Less airflow at higher RPMs due to a valve stuck closed might cause this kind of issues... I just never ran into what you described so I can't say for sure.