Need help finding a boost leak

[BlownAway]

When I give it alot of throttle and my gauge goes between vac/press I hear air coming from somewhere and it backs off really hard. I did a vac check in the intake manifold and everything on the top end is perfect.98 Eclipse gs-t

 

[theSicKness]

Build a boost leak Tester

here is how
http://www.dsmtuner.com/forums/showthread.php?t=169435&highlight=boost+leak+test


Hope it helps
Jesse

 

[BlownAway]

Thank you I will have to definatly try this one

 

[MrBoxx]

Notes on doing a boost leak test:

- Watch your aftermarket boost gauge and see how fast it drops. It should be able to hold pressure for about 30 seconds. Don't go by what your air compressor regulator gauge tells you.

- Don't, under any circumstances, put in too much pressure! 20-25 psi will be enough to detect leaks. There have been stories of people accidentally pressurizing their systems to 120psi and damaging their cars.

- To help narrow down leaks, spray soapy water on likely places leaks may occur: Any soft intercooler hose/couplers, BOV flange, intercooler and intercooler fins, throttle body, BISS, intake manifold flange, and injector seals.

Edit: While your intake tube is off, check your turbo for shaft play.

 

[alex99gst]

To add on with what MrBoxx said, take off the oil cap and listen for air. If you can hear any, your PCV valve is leaking. Also, some bleeder-type MBC's can cause people problems so removing the vacuum line from the boost source and pluging it should help yield better results.

 

[BlownAway]

Iam going today to have my car hooked up to a fogger will let you know the results shortly

 

[oldman]

To add on with what MrBoxx said, take off the oil cap and listen for air. If you can hear any, your PCV valve is leaking. Also, some bleeder-type MBC's can cause people problems so removing the vacuum line from the boost source and pluging it should help yield better results.

Alex, all MBCs will leak, including ball and spring type, disabling the MBC is always step one in leak testing.

Iam going today to have my car hooked up to a fogger will let you know the results shortly

What is this fogger business?

 

[BlownAway]

A psi is a machine produces a psi preasure of 5-8 lbs. Hooked it up to all the vacume lines one at a time to see if anything is leaking or split hoses

 

[PropXprt]

That is a pretty cool idea there. I always wondered how I would know if the "j-pipe" gasket was leaking. I have always leak checked mine by hooking my home-made tester up to the line going into the in side of the intercooler.

 

[knxkenix]

i know this post won't help any. but asking questions. I recently did a boost leak test. but my gauage is not moving at all. i used to push 17 psi on T25. and it runs fine. i just had my clutch folk replaced. after that i am having huge boost leak.
For boost leak test. i searched, and it tells you that you should remove the PCV house. but do you have to cap it or anything? Please help me out.. i can't post anything. i am a new member. (do'nt know how to post).
HKS BOV, EBC, Catback.

 

[alex99gst]

You remove the hose from the intake manifold and cap it off there. You also want to spray soapy water on all the couplers and connections in the intercooler piping to show any leaks that you cant hear.

 

[knxkenix]

Thanks, I will try that out this week. What about the BOV return pipe? Is it the one returning from stock BOV? I am using HKS SSQV BOV. And does my EBC effect any leakage? Thanks again..

 

[oldman]

Recirculate that BOV before you come back for more.

 

[knxkenix]

basically i can't do a boost test with a vented HKS BOV right? What if i place back my stock BOV just for the testing? I really want to fix this right away. I really appreciate ## help.

 

[oldman]

No, you mis-understood.

The intake pipe has to come off during the boost leak test anyway so you don't need to recirculate during the test. In fact, part of the test is to see if the return pipe leaks under boost. Same thing applies to the pcv, you don't want to block off the pcv until you suspect it leaking by listening under the oil cap.

As for venting your BOV, you're losing metered air resulting in rich conditions and can very well the the reason why you're asking questions on boost leak testing, this problem is multiplied if you're tapping your BOV line for your mbc. You need to recirculate the BOV back to the intake pipe for good is what I was trying to say in my previous post.

 

[2fast4]

Something is missing here - I remember years ago, leak test also required cranking
motor where #1 cylinder is TDC. This ensures all valves are closed. Or else, the air will pass thru open valves and you can hear the leak at the exhaust tip.
And it helps to step on gas pedal while pressurizing(or throttle plate).

 

[oldman]

Something is missing here - I remember years ago, leak test also required cranking
motor where #1 cylinder is TDC. This ensures all valves are closed. Or else, the air will pass thru open valves and you can hear the leak at the exhaust tip.
And it helps to step on gas pedal while pressurizing(or throttle plate).

Please explain how putting #1 at TDC will ensure all the valves are closed, better yet, explain how will all valves in every cylinder be closed at any position.

BTW opening the throttle plate will not effect your leak test. Don't just repeat what you've heard, instead you should try and understand it first.