boost problem ?

[Tayhlor VR4]

hey guys my cars not boosting properly im pretty sure its not leaking coz when i floor it the boost doesnt drop it just barely reaches 1-3 psi ? and thats at 6k rpm , blow off valve is silent aswell

[Tayhlor VR4]

i have tightened all intake connections

[Nick Mann]

Can you borrow another boost gauge or get the car dynoed? Or find someone who can do a boost leak test?

[Tayhlor VR4]

During idle is the boost gauge suppose to be below 0 ? There's different numbers under 0 ? I'll try find a pic

[Nick Mann]

Yes, when the throttle is not pressed or only pressed lightly the system will be under vacuum.
Usually the units are mmHg or inHg.

[Tayhlor VR4]

ahhhh i see but even when i rev it past 3k it barely goes past 0psi ? do you have any cheap ways to check for a boost leak ?

[Tayhlor VR4]

In all honestly I think it's the blow off valve it's a cheapy street spec and when I bought the car it didn't have a vacuum hose connected to the blow off valve , I've tried connecting a hose to 3 different vacuum sources but still nothing so I think I'm gonna block off the trumpets on the blow off valve give the car a rev and if the blow off valve is still covered then I guess I'm fcuked lol

[Nick Mann]

The engine needs load to build boost. Just revving will not produce any significant boost. Put the car in 3rd gear on an open road at 2000 rpm and then floor the throttle. That should build boost.

I'm not sure I understand your BOV test?!

[Tayhlor VR4]

But technically I should be able to rev the car in neutral and hear the blow off valve go off just like any other car ? Also is it normal to rev the car a little and the boost drops while being in the vacuum stage ? Like on the boost gauge how you said the numbers under the 0 are for the vacuum well when I rev it in vacuum it drops even when I'm still holding the revs ? Sorry if I'm not explaining myself

[Nick Mann]

When you say the vacuum drops as you rev, do you mean the numbers get smaller or bigger? Less pressure = bigger vacuum = higher numbers. Your vacuum should decrease (smaller numbers) as you press the throttle and increase as you lift off the throttle.

BOVs are awkward to activate when revving in neutral. I can make mine activate but not loudly and only if i give it 100% throttle for a second, then let off to 0% very quickly at over 5000 rpm. Most BOVs have some kind of spring device that holds the BOV closed, to stop the BOV activating on a hair trigger. How this spring device is set will make a big difference on how the BOV activates in marginal activation conditions, and revving whilst in N is definitely a marginal activation condition.

[Tayhlor VR4]

The needle goes down not up , as If it's leaking ? And I've tried the blow off valve with no spring at all and still nothing

[Nick Mann]

Can you take a video showing the boost gauge and the rev counter?

[Tayhlor VR4]

I will do tomorrow ! oh and how do you upload a video on here ?

[Nick Mann]

No idea. Stick it on you tube and link to it.

[Tayhlor VR4]

ok i went out today and sorry wasnt able to get a video but what i found was that the boost gauge actually wasnt reading above 0psi , blow off valve and boost gauge is connected to a good vacuum source right off the back of the intake so im confident that theyre working as they should . im just so confused as to what would be the problem , revd to 5000rpm and didnt go past 0psi on the gauge

[Nick Mann]

I think that I have mentioned previously that the engine needs load to boost. Put the car in 3rd at 2000rpm and then floor it. Then the car will build boost.

[Tayhlor VR4]

https://www.youtube.com/watch?v=3G9t...e_gdata_player in this video the vr4 legnum reaches 7+psi boost easily in neutral ?

[Nick Mann]

What mods are on that car? I'll go and see what boost I can make on mine.

[Nick Mann]

http://www.youtube.com/watch?v=z2fZ5...ature=youtu.be

My car is reflashed and is more aggressive than stock on building boost. My dump valve (HKS SSQV) does sound when I am aggressive with the pedal but only because I have the spring set low. As you can see in the video, I struggle to build any boost in Neutral. My display is showing vacuum as mmHg at the bottom of the display next to the clock, then boost as the next line up in bar. My gauge has a peak hold, so I accessed that after the vid, my highest boost was 0.24 bar and that was obviously not for long when you watch the display.

If I had launch control activated on my car then it would be very easy to build boost whilst in N.

[Mr.Salas]

Is it me or is he getting +5 PSI at in neutral ?? Cause the gauge is divided into 10 PSI sections