Very Loud hissing under boost under dash after boost gauge install.

[crunchymilk]

Title explains it. Under boost, there is a very loud hissing sound coming from underneath the driver side dash It gets louder as the boost increasing, gets really loud under high boost. I just finshed installing a sport comp autometer boost gauge and a a/f gauge 2 days ago. I unplugged the boost gauge and it's a different hiss that's coming from under the dash. This hiss just popped up this morning, but the gauges still read perfect so I'm not quite sure what it is, I don't think it's a "boost" leak since the boost still pegs at 13psi. Anyway, anyone know what this is or how to fix it? Any help is appreciated! thanks!

 

[ddavisaf]

It's 1 of two things. a) Your leaking air through your boost gauge or b) You're hearing air travel through the line to your boost gauge. Might want to check the line for tears or kinks or holes.

 

[crunchymilk]

"It's 1 of two things. a) Your leaking air through your boost gauge or b) You're hearing air travel through the line to your boost gauge. Might want to check the line for tears or kinks or holes."

It can't be either of those though. If I was leaking air throught the gauge it wouldn't read right, but it reads perfect. -17 at idle at 14 at max boost. I'm not just hearing air travel there because it didn't happen at all the first two days. It just started hissing this morning. Thanks for the reply though, anyone else got an idea?

 

[skelly]

Make sure the threaded fittings on the gauge are sealed properly. You shouldn't be able to hear the air moving through the line because air is not supposed to be "flowing" through there: it just pressurizes and depressurizes which is a VERY small amount of motion in the air in that line. My sportcomp Autometer had a small leak internally and I could hear the tone of the faintest "hisss" sound change with the amount of boost/vac that it saw. But it was never "loud". Loud can only mean one thing: a significant leak, whether it's a faulty gauge, or a split hose - it's on you to pin-point it.

It can't be either of those though. If I was leaking air throught the gauge it wouldn't read right, but it reads perfect. -17 at idle at 14 at max boost.

Sure it can. You just don't think it can. You want a surefire way to make this determination? disconnect the gauge from your signal source under the hood and cap it off. When the hiss goes away, you will find we are correct. If the hiss remains, then your problem is entirely unrelated to the gauge.

- SK

 

[ddavisaf]

Wow, you need to post accurate details then. You originally said 13 psi. And you never said anything about 2 days later.



Yes, it CAN leak from the gauge and still read accurately. If it's a tiny tiny leak, it's not going to affect your readings enough for you to really notice.

Obviously you have a leak. you need to check your lines. You need to check your gauge.

 

[crunchymilk]

"Wow, you need to post accurate details then. You originally said 13 psi. And you never said anything about 2 days later."

WOW, you need to reread my original post.

Actually, I could only fit the gauge on about two or three threads max, it wouldn't go past that at all. Is this my mistake or is something wrong with my gauge?

I'll check the lines again, I'll post with the results, thanks.

 

[97ClipseDSM]

i think im having a similar issue. Im not hearing any hissing noises but when my evo III 16 is boosting, sometimes the gauge will read 0 and sometimes itll jump from 0-15 psi, like the gauge is messed up. I also noticed that my car isnt pulling as hard as it should at 13-14 psi. I am starting to think that its my faulty boost gauge lines that is creating a leak.

 

[oldman]

Build yourself a leak tester so you can get down there to look for the leak, fix all other leaks while you're at it.