Blowoff Valve Sound from engine after it is shut off?

I am not sure what to make of this. I have an 2012 V6 Tacoma. I normally don't just start up my truck and shut it off right away but the last 2 days I've had to do it to move it over a few feet with a total run time of maybe 30 seconds. When I shut the truck off the engine turns off but I hear what sounds like the radiator fan or an electric motor still running then about 3-5 seconds later a pressure release sound almost like a blow off valve on a turbo. I was able to reproduce it several times this morning. It only seems to happen when the engine is cold, it runs for a short period of time, I use the brakes, and shift. I am still trying to catch where the sound is coming from but by the time I get to the engine bay there's not enough time to really tell. I was able to see though that that the radiator fan is not moving after the car is shut off and the sound is present.

Any ideas?

 

smog pump, seems to be a common noise from the 12's

 

Thanks for the quick reply. I tried searching but I never would have thought to search for smog pump but now that you mentioned it and I read up it seems to fit the bill. Thanks.

 

Read this.
This guy posted (#7) in on the OP's thread about how he didn't like the noise and was embarrassed about it and demanded it fixed...

He was embarrassed about it in front of people as it must have sounded like a fart or something.

http://www.tacomaworld.com/forum/2nd-gen-tacomas/254847-strange-noise-when-engine-shuts-off.html

 

I haven't heard that sound yet but you probably just saved me some research with the heads up. Thanks.

 

Mine does that when its first started...probably around 10 seconds are the engine is running. Asked the dealer about it on the last visit, they either didn't know or the tech I talked with just didn't give a rip to investigate. I've read elsewhere its normal for that type of engine in the 2012s.

12Tac

 

That motor is used to blow air into your egr system to stabilize your air/fuel ratio upon startup and shut off...its normal

 

Mine does that on cold morning, sounds like a whine noise for a few seconds then once the engine warms up a bit a blow offf sound will emit and it goes away. Seems normal to me!

 

Hahaha! I didn't see that. Thanks for sharing.

 

New here. Glad I found this thread. I had an appointment scheduled for tomorrow to have this noise diagnosed. The weird thing is I never heard this sound coming from my friends 2013 taco so that's why I was fairly concerned. Do all of these have this sound or just a select 'lucky' few?

 

Taco fart!

 

Just got my 2013 and had it in for another reason and got an explanation on what it was but not why it runs after engine shut off for some and not others.

 

Mine does it, it's explained in another thread, same as the high pitched whine from the fuel tank 4 hours after its stopped running, all normal