I have recently bought a used 2000 Volvo S40 and noticed that a hose is missing (it's in yellow) it's right next to the MAP sensor. Is there anyone that could help figure what it's called and what it does? Thanks!!

 

For some odd reason RockAuto calls it an Air Cleaner Intake Hose. I believe what it does is allow air to the throttle body if you quickly let off the gas pedal under boost. With a MAF system all air must be accounted for after it passes the MAF. If you quickly shut off the throttle under boost then that extra pressure has to go somewhere and it will backup into the turbo unless it has an outlet.

https://www.rockauto.com/en/catalog/...take+hose,6344

ÜRO PARTS 30637166

 

Yep it's what Hudini said, a friend had a ruptured one of those and it made a weird noise

 

Yeah, I was having MAF related codes and hesitation as well as rough idle issues on my 2004, Took it to the mechanic, he pulled on the brake vacuum hose that's under the cover to the right of the engine, and it popped right out. He re-did the connection there and reset the codes and told me that air was being sucked into the engine through there, undermining the MAF sensor and throwing codes. He also told me to rev the engine and quickly found the s-shaped hose was cracked and upon removal, it broke into 2 pieces. He replaced it with a generic hose he found in his shop and though it's a little kinked, it solved my issues and I was up and running again.

 

Need help locating where this hose goes too

 

Ummmmm.... maybe the obvious right-size nipple that's almost touching it?

 

I got this picture off line so on my car there is no hose there

 

Then put one there (seems that you even have a link to buy one from rockauto in the post you linked).

Or am I missing something?