My boost leak test results

[Deadly BlaZe]

Ok, finally after a YEAR of owning my car, i finally got my boost leak tested. Strangely enough, there were no leaks except for...the intake manifold where those 4 hoses attach to A,P, etc. there was air coming out from them. Is it supposed to leak boost through there i didn't think it should. I plugged up the holes with hoses and i heard no other leaks. So then why was my car so slow?? So i take the car for a ride. Previously my car boosted to 6 psi at 4k and started spooling at 2.5k...now it goes up to 9 psi @ 3.5k and starts spooling even a little before 2k! could those 4 holes really have affected my boost?

 

[oldman]

except for...the intake manifold where those 4 hoses attach to A,P, etc.

What are A,P?

How much pressure and for how long was the system able to hold? Did you spray everything down with soapy water?

 

[Deadly BlaZe]

What are A,P?

How much pressure and for how long was the system able to hold? Did you spray everything down with soapy water?

i was referring to the 4 emission vacuum lines at the throttle body. i pressurized the leak tester at about 10 psi and just held it on there for like 10 minutes to listen for a leak. the 4 emission vacuum lines were the only sources of leakage. i didn't spray everything with soapy water because i didn't think it would be necessary since i couldn't hear anything.

also i noticed something else...the stock boost guage is as accurate as my autometer. sounds weird, but its true. infact, the stock one responds quicker to boost than the autometer.but they read the same boost all the time

 

[exile]

The reason it responds quicker is because it's more sensetive and has a smaller scale than your accurate autometer. That boost guage is basically there to show you that your turbo is working.

 

[oldman]

Bring the pressure test up to 20psi.

 

[Deadly BlaZe]

Bring the pressure test up to 20psi.

i was thinking i should do that..but i didn't wanna risk screwing up the turbo or anything else.

 

[oldman]

i was thinking i should do that..but i didn't wanna risk screwing up the turbo or anything else.

Not to worry, some of us that are running 25+ psi pressure test our systems to 30psi if not more.

 

[1glaserturbo]

I believe, if I'm wrong someone correct me, those lines are for emissions only and should have no effect on your boost. There is a vacuum diagram running around here somewhere, let me take a quick look and I'll post it up for you.



Chris

Edited: There ya go!

 

[ddavisaf]

Here's the diagram. It's a good idea the cap the ports on the TB. Pressure test at 20 psi and you should hold that for at least 30 seconds. Use soapy water to pin point leaks.

 

[ddavisaf]

Doh! Beat me to it

 

[wallyman]

They're not only for emissions but yes they shouldnt be affected by boost. One runs to your egr valve (Green Line) one runs back to manifold which the (Yellow). EGR valve essentially raises octain by recirculating exhaust. By removing those your probably have a performance loss due to the computer retarding your timing becuase its seeing knock.

 

[wallyman]

I did my boost leak test also and found that my PCV is sliglty blowing through. How critical is this and can it cause fuel cut?

 

[ddavisaf]

Yes and No on the fuel cut question. If it's allowing air *through* the valve, replace the valve with a good OEM one. If it's leaking past the treads, teflon tape it.
The fuel cut question is to in depth for me right now, Read the www.vfaq.com for a good description on fuel cut.

 

[Deadly BlaZe]

They're not only for emissions but yes they shouldnt be affected by boost. One runs to your egr valve (Green Line) one runs back to manifold which the (Yellow). EGR valve essentially raises octain by recirculating exhaust. By removing those your probably have a performance loss due to the computer retarding your timing becuase its seeing knock.

why is it then that when i applyed the leak tester, there was air coming through the 4 lines. as soon as i got in my car after i plugged them up, i started boosting higher and earlier.

 

[wallyman]

Not to sure would have to look at it a little more. Are your lines routed right? i think it lines go in this order starting at the furthest. Red, Green, Yellow Black. I know i had my green and yellow crossed and it was affecting my EGR valve.

 

[Deadly BlaZe]

Not to sure would have to look at it a little more. Are your lines routed right? i think it lines go in this order starting at the furthest. Red, Green, Yellow Black. I know i had my green and yellow crossed and it was affecting my EGR valve.

no im definatley not sure that i have my lines routed correctly, i just kinda put any of the 4 hoses i saw anywhere.

 

[wallyman]

DOH not good. Some are low vac lines used at low RPMS and others High vac lines used at High RPMS. For example, the green and yellow lines are only used when the engine is high up RPMs. They actuate the EGR like I said before. Its an easy fix. Let me know how it goes when you put them back in the proper locations.

 

[ddavisaf]

http://www.dsmtuners.com/forums/showthread.php?t=198327
Good job guys