raywong

my turbo guage reads 0 psi at idle everytime I start the car. But after a few minutes it will return to normal(-7 psi).
Is this normal? Maybe this is why I have no power at all below 4500 rpm?

webguy330i

iTrader: (17)

Have you been watching your rpms when you start the car? It should be idling slightly higher than normal-warm idle, ~ 1500 if it's cold. If that's the case of course you're not going to be at the max vacuum.

sr20det91

iTrader: (59)

You tapped vacume in the wrong place. I assume after the Fuel Pressure Regulator. You need to tap before it. Its the very short hose coming off the top of the intake madifold on the passenger side you need to tap. You cant miss it.

Do a search and you will find pics. I made the same mistake.

BTW..normal vacume is around -17PSI not -7.

raywong

the installation is good.
this happens even when the engine is hot. and it only last for 5 minutes at most.

sr20det91

iTrader: (59)

Yea, thats the exact same thing mine was doing.

Where do you have it tapped in at? Because the only other thing it could be is a defective guage or pinched hose.

MalibuJack

iTrader: (5)

it sounds like you tapped into a timed vacuum source... (Like the line that runs to the EGR valve if our cars even have one)

ez76

iTrader: (5)

I'm running the OEM boost gauge and it shows more like 30-35 cm Hg of vacuum at idle (but boost reads correct). The gauge was installed at the dealership - did they tap the wrong thing?

MalibuJack

iTrader: (5)

It seems a little high.. but if the sweep is at 0 when the car isnt running, and boost reads correctly there may be a slight kink especially if its slow to respond.. My vacuum typically reads between 17-23.. Boost, Well that may read as high as 21psi on occasion (grin)

MalibuJack

iTrader: (5)

BTW the easiest line to tap for a boost gauge (and one that reads most accurately) is either the vacuum line to the fuel regulator, or the line (on the valve cover) that goes to the Diverter Valve (Recirculating Blowoff Valve)

Any of the other locations that come directly off the manifold can work also, but it really depends on what is hooked up to it since some sources go to vacuum actuators, some might be vented through a 1way valve (in which case you might get a reading of boost and no vacuum or vice versa) However I don't recall seeing anything like that since venting anything will affect Idle and drivability...

raywong

the problem disappeared this morning. I tested over and over by restarting the engine, and it is the normal -0.5 bar @ idle.
after 20 minutes of driving, I restarted the engine again to check, it became 0 bar again.
I am convinced something is leaking, probably a valve?

rarson

What is with this thread? The units are all over the place. Typically, a boost gauge that reads in psi shows vacuum in inches of mercury (in Hg). Two inches mercury roughly corresponds to -1 psig, but it's not correct to say "negative psi" because psi is a measure of pressure, not vacuum. Or you could always refer to it as psia but that's just stupid because everyone reads boost in psig and vacuum in in Hg (unless you're reading it in bar, atm, or mm Hg).

raywong

I brought in my car to the garage, and they are having all my vacumn hose and the actuator replaced. I hope this will fix the "0 bar" and "late turbo boost" issue. Otherwise, I will replace the BOV next.

909

Ray,

what kind of boost controller are you using? Normally EBCs have 3 vacuum connectors - turbo, actuator/wastegate and intake manifold. I think it could be the intake manifold hose that's leaking or wired wrongly.

Good luck

lil'evil_evo

iTrader: (17)

Correct this should be all it is.