Vacuum is tooo low!?!

[deviousgst]

I just installed my freshly rebuilt motor and hooked up everything, and I rechecked all the vacuum lines and made sure everything is hooked up correctly, but my vacuum still sits at 5 at idle..any ideas?

I'm going to go to the hardware store and make me a boost leak tester - any recommendations?

Thanks in advance.

 

[LiquidX]

You have a leak. Do a boost leak test.

 

[deviousgst]

You have a leak. Do a boost leak test.

Yeah, that's what I'm going to do.

You just pressurize the stem with around 15psi and spray soapy water and hold the TB open and see/hear for any leaks on the lines at tdc? Correct or no.

 

[Defiant]

You're tapped in to the wrong place for your vacuum signal, or the hose is kinked or collapsing.

Be more careful with your spelling.

 

[deviousgst]

found one leak..and fixed it, now vacuum sits at 8..and I cant find any other leaks...wtf

 

[bomper04]

where are you tapping in for your source of vacuum? is your idle higher than normal? remember, there's a difference between manifold vacuum and port vacuum.

 

[deviousgst]

where are you tapping in for your source of vacuum? is your idle higher than normal? remember, there's a difference between manifold vacuum and port vacuum.

What do you mean my source of vacuum?

 

[95TalonOwner]

Where is your boost gauge hooked in to for the vacuum/boost signal?

 

[bomper04]

What do you mean my source of vacuum?

when talking about vacuum there are 2 sources. manifold vacuum and port vacuum. manifold vacuum should usually sit around 17-22inhg, that's vacuum measured AFTER throttle plate. BEFORE throttle plate is port vacuum. there's a difference, hope this helps.

 

[97gst_spyder]

One of the best places to hook up a boost/vac gauge is the 'P' connector on the throttle body.

 

[johnovision27]

I have mine hooked up after the Throttle Plate and I'm getting a constant 11ish inHg
I put a Y splitter in one of the hoses coming from the back, can't recall what one.
Where exactly is this "P" connector?

 

[97gst_spyder]

On the top of the throttlebody. If its a 2g throttlebody, it will be the one closest to the front of the car.

 

[deviousgst]

my source of vaccume is the the nipple of the intake...its t'd off

 

[rhodess89]

get some starter fluid and spray in areas of vacuum lines and where gaskets meet, if idle rises you know there is suction from somewhere.

 

[ziggo0]

Or......he could be running so lean it's causing the engine to run like poop....turns out my car was running HIDEOUSLY lean when I got my maft on a fresh rebuild....was bouncing anywhere from -12 to -8 with TERRIBLE idle quality....richen it up after getting some datalogging, sits right at -18.

 

[GooeyGus]

my source of vaccume is the the nipple of the intake...its t'd off

The intake before the turbo? As in where the air filter attaches?

It needs to be at the manifold, but make sure it's the right nipple.

I changed where my boost gauge is tapped in yesterday because the previous owner had it in line with the BOV. I tapped the wrong port and my vac reads 0 until the car warms up, then it is fine. That's just an example of why it needs to be connected to the proper location

 

[tkhaab_94]

It can also be your boost gauge that is reading wrong.

 

[deviousgst]

finally had time to check my timing to see if thats why my vaccume was low and bouncing neelde... and it was off a tooth. now it all good steady at 15 at idle