-10 psi at idle , vaccum leak?

[318Batman]

alright heres the deal.
my buddy just picked up a 1997 GST, only mods are thermal full 3" exhaust, real type s BOV, boost controller , and HKS 264 cams. I've read that vaccum is supposed to be between -16 - -20 at idle. this car is showing -10 at 6-800 RPM's.
any help would be great, we both are new to DSM's

 

[BurrowZ]

Just so you know, that spec is -20 in/hg. Not PSI.

And cams will make your vacuum decrease, mine is a solid -15 in/hg at 900 rpm. Try bumping the idle up more to see if that helps. Otherwise you can do a boost leak test to find any vacuum leaks.

 

[Diamond Star Werks]

-6psi is about 20 in/hg. You vacuum is close to 30in/hg if its ,10psi. Mine is -7psi right now idling at 950-1000. With cams. Which is aproxx 20 in/hg.

 

[snowborder714]

-6psi is about 20 in/hg.

-6 psi would actually be about -12.2 in/hg. It's pretty close to a 1 psi to 2 in/hg ratio.

 

[318Batman]

So, best thing would be to perfrom a boost leak test?

 

[snowborder714]

That's always a good idea.

 

[318Batman]

Alright, thank you

 

[DSMTyson]

Religiously do boost leak tests. Sometimes they come out of no where..

 

[niddydsm]

^^^+1 i do a boost leak test every week!!!! but i also run the living shit outa my car...

 

[cnordelo]

Another thing to try is spraying carb cleaner on your couplers and listen for change in idle. If it does have a boost leak.

 

[318Batman]

The vaccum line for the fuel rail was off , fixed the problem guys

 

[Diamond Star Werks]

-6 psi would actually be about -12.2 in/hg. It's pretty close to a 1 psi to 2 in/hg ratio.

Thats correct. I actually posted the measurements myself in a diff thread. Though I just switched from a,digital to manual gauge,and digital read -6 and manual reads about -17-18 in/hg hmm guess that tells me,one of these gauges,are off.