I was reading BfB's post last night but I don't think it answered this question....At idle, full vacuum, inside my truck, I have a vacuum-leak like sound. Constant - sssssssssss - at idle. As vacuum changes with throttle increase - it changes as well. And of course, when I get into the boost, it's gone.

Normal? Should I be hearing it in the cabin? Do I have a leak somewhere?

Guess I should mention that I the JDM Stage I & II mods (boost bypass included).

Any info is appreciated.

Thanks,

Dan

 

does your boost guage work?

I have seen the vacuum line to the guage become loose or chaffed causing a vacuum leak.

also your heater/ac blend doors all work off of vacuum, so you could have a leak on one of those hoses. If you have a bad enough vacuum leak on your climate control system, all airflow will default to the defroster vents. so check out your a/c and see if the goes to all the right places when you operate your control switches floor/panel/defrost etc.

good luck

later,
chris

 

Boost gauge works. All vents work correctly according to switch position. When A/C is on (which is always lately!!!) the fan blows through the vents. FWIW..the vacuum noise does not change if I'm changing switch positions for the heat/def/floor/AC. So I don't think it's related to those.

Is the vacuum line to boost gauge accessible from under the dash without having to tear anything apart?

Thanks for the info..

Dan

 

If i remember correctly, you can see part of it from under the dash, but to really get at it you need to remove the instrument cluster.

I'd advise removing the source of vacuum to the guage at the intake.

I can't remember where the vacuum line comes from, I want to say that it comes through on the driver side right straight through the firewall, but on second thought it may very well come through behind the glove box on the passenger side and run along side the HVAC (multicolor) vacuum lines. look for a small diameter hard plastic line colored white I think. this is your boost vacuum supply.

anyway, unhook it at the engine thereby removing the vacuum, if the noise goes away, then you know you've at least narrowed the leak down to the boost guage or supply line.

good luck,
chris

 

Thanks for the info, Chris. Appreciate it.

Dan