Typical boost/vacuum gauge readings.
 

Installed a boost gauge into my car. Works sweet, looks nice. But it dawned on me that its fairly useless as i dont really know what a normal reading is. It boost an hold steady at 17psi which i was tuned for, that much i know. But when im cruiseing it sits at -26inhg and when im stopped and ideling it sits at -22inhg. Are these typical values for a healthy wrx? Its a 2.5L btw. Reason i ask is i am experiencing random rough idle and every now and then, its very rare the car will hunt once whilst idleing. Also whilst the car is ideling it will burp randomly, but not very often.

also should of mentioned that i have 3" TBE.

Did an online search and found this, pretty much what mine reads with the same mod.
[url=http://www.iwsti.com/forums/2-5-liter-litre-factory-motor/74033-help-high-vacuum-reading.html]help. high vacuum reading... - Subaru Impreza WRX STI Forums: IWSTI.com[/url]

That's normal, mine also sit around there when I'm cruising off boost and I run 26 psi everyday

I'm using a Defi BF Boost Guage - hooked into the intake manifold.

PS. Just realised I'm no longer a paid subscriber too... must have missed that email for repayment?

Yeh hooked into the same spot. But im using a prosport evo.

22inHg (75kpa) seems a little high on my books for idle.

i would guess it would be running a little rich (and potentially fouling)

effortless cruise load and idle on the gauge should almost match.

I would expect around 40-60 kpa on idle.

To convert a unit from inch of mercury, conventional (inHg) to kilopascal (kPa), multiply by 3.386389

My defi shows -75kpa at idle as well, connected to manifold, tuned by race torque.

Sorry i should clarify. Effortless cruise it is sitting flush with idle, but when im cruising and i let of the accel to slow it sits at 26ish depending how much i let it decel.

I guess it also depends on what speed you idle at, at 850-900rpm i log around 60kpa, on hard decal it falls below 40kpa.

2.5 might be a factor too.

[QUOTE=tuna;729861]I guess it also depends on what speed you idle at, at 850-900rpm i log around 60kpa, on hard decal it falls below 40kpa.

2.5 might be a factor too.[/QUOTE]

I'll log mine and update. 2.5l and not heavily modified.