vacuum / boost gauge question

[gnes100]

I just installed my boost gauge into my car !! well at idol it only shows for vacuum 15 hg when im driving and let off the gas it will hold down at 20 until i push in the clutch, it will raise back up to 15 -- and hold steady at 15.

Do i have a boost leak or is one of my valves sticking or something ???

I also have an evo 16 g turbo - it will hit 10 psi at 3000 rpm and rise to about 12 by 4200 but at about 5500 it drops down to 10 again .

RIght now my only mods area evo 16g and 3 in exhaust w/ no cat

 

[ddavisaf]

Do a boost leak test.

Are you running the turbo off the wastegate or off a manual boost controller?

 

[gnes100]

right now I'm running it off of the stock boost controller.

is there a correlation between boost leak and low vacuum?

 

[ddavisaf]

Usually with a boost leak your readings will be sort of bouncy. I was thinking your weren't running off the stock boost levels. I can't remember off the top of my head when normal vaccume levels are. They vary from altitude to altitude. What you can do though, just to make sure is go over your vaccume lines and make sure none are torn or disconnected. However, I think you're not out of the normal range.

 

[project15]

im pretty sure that the vaccuum is supposed to do what yours does. mine is around 18 with clutch in and 21 while decelerating. i've also read too that someone else said this was common.

 

[gnes100]

OK i was just checking to make sure, because i have an 01 toyt celica w/ supercharger and that reads 20 all the time weather at idol or decellerating .. thanks for the reply s

 

[SoonToBeDSM06]

Yea it is more likely a vacuum leak passed the throttle plate. Put the leak tester on the throttle body elbow and test if from there. Listen for leaks coming out of the lower injector insulators, throttle body gaskets, BISS o-ring, or intake manifold gasket. those leaks would bring your vac to 15 because mine did that for the longest time. Hope that helps

 

[oldman]

OK i was just checking to make sure, because i have an 01 toyt celica w/ supercharger and that reads 20 all the time weather at idol or decellerating .. thanks for the reply s

Unless you have after market cam, 15Hg (18Hg is where it should be at IDLE is an indication that there are boost/vacuum leaks, especially if you're experiencing inconsistent boost levels. Perform that boost leak test and post back.

 

[Defiant]

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