I've tried doing some research here, but not sure what i'm looking for. just recently i've been driving and after shifting into second and giving it some gas i hear a hissing sound from the engine. it goes away, then i shift into third and give it gas and the hissing comes back. when i floor it a little more you can hear the hissing. any ideas? i have 96 civic with b18 i bought from a friend. i kno very little about cars and i'm just looking for some help. thanks

 

since its when you floor it it most likely is the sound of the intake sucking....ive heard this sometimes before

 

how does it idle? I'm guessing vacuum leak. Could be intake though, if your exhaust is quiet enough to hear it (ie stock exhaust).

 

you should here my throttle bodies under partial throttle, there's some hella hissin.

 

Aftermarket intake.

 

it has an SI exhaust and stock intake. its not when i always floor, but when i shift gears and add gas i can hear it, but it does go away. is this bad?

 

vacuum leak. Check all the vacuum hoses.

 

why does it only hiss for a short time and go away? is this hard to replace or expensive? i'm thinking about just going to a shop in town.

 

when the car is running, look around the intake manifold. if you see any little holes open, go to autozone and get some vacuum plugs. that's all you need, and it'll cost under $5. If that is the cause of the sound. I'm still guessing it is though. the hissing sound will be louder with a small opening than it will through a large one.