Boost Leak behind dash?

[Raptorbh12]

At anytime that i hit boost, i hear a loud air leaking noise right behind my dash and a few seconds after hearing it i even smell a slight gasoline type smell. Could this sound be from a leaking stock boost gauge line? I have no idea if its hurting my performance because its always been like this since i bought the car.
To be more specific the sound seems to come from more the left side of the dash near the left air vent... its wierd and my friends nor myself can figure it out.

 

[xveganxcowboyx]

It's not from the stock gauge as that uses a signal from the ecu, not vacuum line.

Is it possible there used to be a boost gauge there, but someone removed it leaving the vacuum line?

Otherwise try looking on the engine side of the firewall. There are several lines that see boost/vacuum at the top drivers side (where you are describing the noise). Make sure none of them is leaking.

 

[spoolup]

My bet is on vegancowboy. I have seen people who sell their car and remove the part and do a half ass job. SAFCs removed without reconnecting the airflow wire. Powered accesories removed leaving the bare wire exposed to short a few weeks later (these are fun to find). Boost gauges with the hose just dangling by the gas pedal. Most people run the boost/ vacuum line thru the boost for the steering colum. Look around there, if you have a line going into the car, you have a problem, you will then have to follow it and plug/ remove it and correct the hose in the engine bay.

 

[Raptorbh12]

Is it possible there used to be a boost gauge there, but someone removed it leaving the vacuum line?.

Very possible. i know this car had a ton more modifications before i bought it and it was reverted to as close to stock form as possible. stock intake, internals, exhaust with a 255 walbro and a shep racing trans... so you know this guy had more than the current 14b the cars running...
ill go outside and check for the vacuum lines around the drivers side fiewall. how do i tell if they are leaking though, i even made a boost leak tester but cant seem to pressurize the system.

 

[spoolup]

then its a big leak. First look inside the car where the steering cluom goes thru the firewall.

 

[xveganxcowboyx]

Are you using a compressor or trying with an electric or foot pump? A compressor is the only way to pressurise a system that has any sort of leak.

Look for the old boost line first. It shouldn't be too hard to find if it is there.

 

[fallenauthority]

Sorry to bring this thread back from the dead but I figured i would answer this question so if anyone else searches for this they have the answer.
I am almost 100% sure that your problem is the vacuum hose from the brake booster to the intake manifold. When these cars came from the factory they had a check valve in the line, and sometimes when people swap motors or the line breaks they just assume its a normal vacuum line and throw any vacuum line on there. Or the check valve gets stuck open and will allow a bunch of boost to run into your brake booster, two symptoms of this exact problem are the hissing behind the dash under boost and also if you go from full boost and let of the gas right away and hit the brake pedal it will be really hard to press, thats cause your brake booster is pressurized. I went to a junkyard and snagged the whole line from a car.

 

[Demon5spd]

If it sounds like its coming from behind the dash i would check the stock boost gauge.

The stock boost guage is not a vaccum guage it just a electronic guage that the ecu sends signals to to show a estimated amount of boost and is in now way a accurate measurment

 

[Defiant]

The stock boost guage is not a vaccum guage it just a electronic guage that the ecu sends signals to to show a estimated amount of boost and is in now way a accurate measurment

In comparing the factory "gauge"'s values alongside an aftermarket mechanical gauge, you will find it to be surprisingly accurate. Particularly on a stock engine.