Help with boost leak

[Ginger_Extract]

Hey All, been trying to track down an errant boost leak, and I was hoping y'all could help me, since I'm having a bit of a brain fart.

I've been using this helpful N54T thread about 30FF and finding boost leaks: http://www.n54tech.com/forums/showthread.php?t=13114

Background: N54, 6MT cat. The car has been slow to come onto boost, i.e. can barely make 10psi by 4500rpm, even on E40 blend/Map5 JB4 and was constantly under-target in the logs and generally felt like a dog.

Tested the diverter valves, found that they were leaking above 10psi in one and ~15 in the other, okay. I replaced with a new CP and Tial BOV.

The car feels better, comes on to boost a bit smoother and is able to make more peak boost, but is still under target except for a brief window from ~6000-7000rpm, ha. Interesting, on initially tip in, the car is always right on target for boost, but about half a second into the pull, the car gets heavy throttle closures and goes back to being way under target boost.

Here is where I need your help, and where I am at present.
Tonight, I resumed vacuum testing components on the car, but my brain is a bit frazzled and I can't process the information I found.

In the N54T thread, they say the following:

"Vacuum to Wastegate solenoids
Follow hose from the top a canister to a solenoid. Remove hose at the solenoid and connect vacuum gauge. Start car, gauge should read about 26” Hg at idle. Don’t know acceptable limits but if it’s much lower than 26” trace ALL hoses all the way back to vacuum pump (behind oil filter). Replace leaking or pinched hose.
Reconnect the hose and repeat the vacuum test on remaining solenoid. "

Preface: I'm using a space piece of tubing to do all of my testing below. This line is tested leak free.

- Okay, so I do this, and both boost solenoids are only drawing ~15-16" vacuum. The rear solenoid's numbers are erratic and kind of bounce around while the front one stays at 16" when the car is on.

Again, using the same piece of test tubing, I hooked my vacuum gauge up to the vacuum canisters, i.e. the last source of vacuum before the boost solenoids, and they both have no problem putting out 27" of vacuum.

------

Does this mean that both of the boost solenoids are out of whack/dying, or am I doing this wrong?
My next course of action is to put a vacuum pump (the trusty MityVac) on the "in" nipple of the solenoid and the vacuum gauge on the "out" nipple and test leak down. Alternatively, can I jam the voltmeter into solenoid and test voltage? If so, please advise on figures I should be seeing.

I'm all for second thoughts and opinions. My brain isn't processing this information, so I'm getting a bit flustered. Thanks!

[2PUTT]

here is a simple test i used to do with my B5 S4. helps if you have a boost gauge. unplug the solenoid harness (hoses should still be connected). drive the car to an open area where you can do a few WOT pulls. the car should peak at the boost where the wastegates would open naturally. for the B5, this was about 7-8psi. if it fails the test, then you will need a new solenoid.

usual culprits for boost leaks - IC or CP.

hope that helps.

[Willortiz]

Updates?

[Wolfie1]

very newb question but can you hear boost leak? I'm feeling like my car is low on power but only when I'm under really heavy throttle or times the boost pressure should be high... And it seems like you can hear the boost leak..

[kprocivic]

Originally Posted by Wolfie1

very newb question but can you hear boost leak? I'm feeling like my car is low on power but only when I'm under really heavy throttle or times the boost pressure should be high... And it seems like you can hear the boost leak..

I don't think a leak loud enough to hear would not throw a code.

[Wolfie1]

Originally Posted by kprocivic

I don't think a leak loud enough to hear would not throw a code.

Yea it's weird but I can definitively hear a noise that sounds almost like something is flapping and the power seems way down under full throttle. I am confused.

I am going to try and take the belly pan off to double check that my intercooler is all good. In another thread I was asking how to tell what kind of intercooler I have becuase I can see evolution Racewerks couplings but idk if it is the ER intercooler. That right there could be the source

[titium]

Originally Posted by kprocivic

I don't think a leak loud enough to hear would not throw a code.

most definitely not. when my charge pipe blew and was off it didn't even throw a code....

new charge pipe had a meth bung loose for about 2 weeks clearly audible whistle again no code

[Wolfie1]

Originally Posted by kprocivic

I don't think a leak loud enough to hear would not throw a code.

I think my drive train BOV is not holding the amount of pressure it should be and that's what I'm hearing

[kprocivic]

Originally Posted by Wolfie1

I think my drive train BOV is not holding the amount of pressure it should be and that's what I'm hearing

Mine leaked at 18psi. Easy fix.

[Wolfie1]

Originally Posted by kprocivic

Mine leaked at 18psi. Easy fix.

How do I diagnose for sure and fix??

[kprocivic]

Originally Posted by Wolfie1

How do I diagnose for sure and fix??

I'm not a pro. I just changed the chargepipe and bov. And my logs are consistent now.

[Wolfie1]

Originally Posted by kprocivic

I'm not a pro. I just changed the chargepipe and bov. And my logs are consistent now.

Ahh are you an N54?

[kprocivic]

Originally Posted by Wolfie1

Ahh are you an N54?

Yea n54. I didn't have time to search for a leak so i changed all vacuum lines as well.

There is a good diy on the forum for boost leaks.

[Wolfie1]

Originally Posted by kprocivic

Yea n54. I didn't have time to search for a leak so i changed all vacuum lines as well.

There is a good diy on the forum for boost leaks.

I'm an n55. I'll take a look thanks man