crossed wires, a short, exposed wiring.
Another possibility is shoddy wiring. My 2008 GTS came with a 10" subwoofer set-up with a shoddy factory install that had power and ground cables for the amplifier routed on the same side of the vehicle which can cause this hissing sound. I rewired it myself instead of waiting for a Mitsu dealer to do it for me, and the hiss went away.
Exhaust leak? Vacuum leak?
coz ur momma is in ur bonnet!
maybe clogged air filter or carburettar is sucking air and needs repairing
Might want to check the catalatic converter. if it is that, it's gonna be spendy unless you just drill a hole in the pipe.
A ferret that make a hissing sound means they are annoyed or irritated
A cracked air cylinder could cause a hissing sound in a shock absorber during rebound. Another possible cause could be the seal.
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.
it makes hissing vocalizations
Snakes are reputed to make a hissing sound.
Could be a "hissing" sound
they make a hissing sound