Vacuum Sound at Start Up

[07SMLT]

Ok, I did a search, but can't seem to find any references to my issue.

I have a '07 LT. It makes a weird sound on start up when it's cold. The only way I can describe it is it sounds like a muffled shop vac. Starts instantly, then fades out. Last for anywhere from 10-40 seconds. Any ideas?

 

[The_Roadie]

Totally normal and expected. It's the SAIS (Secondary Air Injection System) turbine air pump. It injects air into the exhaust manifold to hasten the engine control's entry into their low-emission closed loop mode.

Sometimes they get filled up with condensed water and freeze or break or make extra noise. Keep watch for this.

ADDED: They sit on the frame rail underneath the truck below the driver's seat.

 

[07SMLT]

Wow, that was fast! Roadie, you are the man. Thanks for your help here and at offroadtb.com.

 

[The_Roadie]

Don't get used to it.



Thanks for the kind words, though.

 

[silverunicorn]

I bet it's just like this

[video=youtube;pOdidnHcPhU]http://www.youtube.com/watch?v=pOdidnHcPhU[/video]

And, as always, Roadie is correct.

Chris

 

[07SMLT]

That's it! Sounds like a "muffled shop vac", right?

Yes, I'm new, but it's easy to tell that Roadie is like a TB/Envoy wizard or something.

 

[The_Roadie]

You guys slay me...

 

[silverunicorn]

That's it! Sounds like a "muffled shop vac", right?

Yes, I'm new, but it's easy to tell that Roadie is like a TB/Envoy wizard or something.

Indeed!

I like to think of The Roadie as the Trailblazer "Rainman"



Chris

 

[07SMLT]

Bwahahah!!

Only on Sunday, o-o-only in the driveway, d-d-definitely boxer shorts...Kmart sucks!

 

[scottp8113]

Just wanting to confirm that I have a similar noise and not start a new thread. Only mine makes code 0411 pop when it dies down...

https://skydrive.live.com/redir?resid=F279CCF38ED96132!617&authkey=!AMOTzZunn0xxMtI

 

[vipergg]

Just wanting to confirm that I have a similar noise and not start a new thread. Only mine makes code 0411 pop when it dies down...

https://skydrive.live.com/redir?resid=F279CCF38ED96132!617&authkey=!AMOTzZunn0xxMtI

That means there is some sort of issue with the secondary air injection setup. Not seeing enough air from the pump or the valve is stuck or not functioning correctly. Most times it appears to be an issue with the valve . I got this a little while ago and then it just cleared itself and haven't seen it in like 3 weeks . Here is a whole TSB for troubleshooting this from a dealer perspective. http://www.2carpros.com/questions/chevrolet-trailblazer-2006-chevy-trailblazer-p0411-code