since you did not go into any great detail about the noise i am going to guess that there is a leak somewhere between the air filter and the intake. possibly the throttle body area.
Vacuum leak or your window is open.
it makes hissing vocalizations
wild geese makes a hissing sound
All Snakes Make A Quiet Hissing Sound.
A spider makes a kind of raspy, hissing sound.
When a cat is spitting, it makes a sharp, hissing sound.
A ferret that make a hissing sound means they are annoyed or irritated
No, it's usually a vented cap design.
When threatened, the kowari makes a loud, sharp, staccato chattering sound. They also make a hissing sound in defence.
The solution in the clue of the hissing serpent is that the serpent is a symbol for the letter "S". This can be seen in the English language as the letter "S" is often written in a similar style to the hissing serpent with a curved line that has a single point at the end. Additionally the hissing sound that a serpent makes is similar to the sound of the letter "S" when it is pronounced. Therefore the solution to the clue of the hissing serpent is the letter "S".
To make a humming or hissing sound, like an arrow or ball flying through the air; to fly or move swiftly with a sharp hissing or whistling sound., A hissing and humming sound.
Geese make a hissing sound.