2013 Sierra 5.3 Intake Tube

[BarryKH]

I've been noticing on the intake tube, right in front of the throttle body, is a square box like area protruding out the front of the tube. What does it do?

[CamGTP]

It's like a sound chamber to reduce the intake induction noise, think resonator but for the air intake.

[dna9656]

I think you're talking about the Mass Air Flow Sensor. It has a screen (sometimes a wire) in it that measure the speed (?) volume/mass (?) and temp(?) of the incoming air. One thing I know for sure is if it's broke your car won't run; oh and the other thing I know: they ain't cheap.

[CamGTP]

The MAF sensor on 2009+ trucks is built into the airbox lid, it's real slim and nothing like the 2007-2008 as well as previous model years.

 

The 09+ intake has many chambers.