BLKMGK, when I had my issues, I found that it was with the vacuum line circuits running from the DVs to the Ts and beyond. Once I removed the DVs, I started tracing the vacuum lines and found a "T" had a hairline crack in it. That caused me to chase down all the hoses and make sure they were all in good shape. I removed the bumper and the tail lights to check the boost hoses coming from the intercoolers. Not sure it got me much... I have a SAMCO bose DIY thread somewhere that shows pics of some of these areas...I also had the MAFS replaced in the process of troubleshooting and that didn't correct my boost pressure loss... it defenitely sounds like you have a leak!

Mike

 

Any problems with oil leaking out? 25psi is a lot. I've been told 7-10 psi max. I did a leak test trough the air intake once @ 25 psi and ended pushing oil through the main seal. Scared the@#%** out of me. Also, is ther any advantage doing the test on the turbos versus doing it on the air intake? Much easier to do on air intake IMO.

 

Yes you'll see less oil being pushed at lower pressures. However our cars run a bit more than 7-10PSI and the intake tract needs to be able to withstand more pressure. 25PSI is indeed alot - nearly 2BAR. 20PSI would probably be about all you'd need to test this but you'll probably still push oil. The main seal is a concern of mine, I don't want to pop that! However, again, it ought to be able to take this. Mind you I'm not pressurizing the system for lengthy periods of time either!

As for doing it at the turbos - only advantage I can see is that you aren't pressurizing parts of the system that normally never see pressure. The intake hoses down to the turbo don't ever see pressure and might not be happy seeing 20PSI put to them. However it IS much easier since it can be done from up top with a single pressure connection. I'm going to go ahead and pressurize everything and if I find the intake hoses leak a little I won't worry about it.

I'll take Mike's advice and look over the vac lines around where the DVs were today. Honestly I don't think I was hearing enough air leaking for this to be it but who knows, it would explain some of what I was seeing if the DVs weren't activating right - they appeared to be in good condition and had certainly been swapped previously. <shrug> What bothers me is that my car had been making great power, then was worked on some when I had a bad hydraulic leak, and then I noticed it had less power after. I cannot imagine any hoses being pulled during that service and while they drove the car, probably hard, that shouldn't have done this either. Very weird!

 

Yes, you will be checking the DVs themselves if you pressurize from the turbos. If you pressurize at the MAF area, you're putting pressure on both sides of the DVs and won't know if they're leaking. That was my point earlier.

Still not a bad idea to lightly pressurize from the MAF area to see if there are any leaks post MAF/pre turbo that may be screwing up the air metering.

 

Ah gotcha' and I agree! A bit more work I'd think but certainly a good way to catch a bad DV. I had been trying to workout if the DV would act differently pressurizing the way I am and pondered exactly the problem you point out. I wasn't sure exactly how it would react and figured I'd simply try it - and then heard hissing back there We'll see how it goes when the DVs are swapped, I still think something else is up but hope to at least eliminate the hissing. It really is a PITA having so little access to the engine Geez now you have me thinking about building plugs to test from the turbos forward!

 

I think you'll be good either way since you're replacing the DVs anyway. If not, another 20 bucks at Home Depot and you're good to go

 

So I found the leak. It was at the back of the air intake between the main aluminum intake and the plastic cross over tube that runs behind the engine to the passenger side turbo.

What a nightmare. The clamp was stripped. Even with the engine lowered a few inches, it is almost imposible to get there. Not to metionned that I dropped a ratchet back there. Finally got it done. One thing I must say, the quality of the OEM clamps and the plastic tubes is really poor.

One thing I wonder though, If a leak is on the intake side (before turbos) does it affect performance? I would think it doesn't. The only thing bad is perhaps sucking in some un-filtered air. Am I right?

 

Biggest issue with a leak on the intake side is that the engine can receive unMETERED air. That's air that goes around the MAF and can lead to a LEAN condition. This is NOT good and should be avoided if posisble. It would have to be a decent leak and you'd probably throw a CEL before it got too bad but better safe than sorry.

I picked up parts for the test via the turbo intakes. Cheap at Home Depot and built in minutes. As soon as my DVs are in I'll test from the MAF and from the turbos if I can easily do it. If nothing I have the parts and can troubleshoot further if I still have issues. Hopefully this will be all I need!

I did look into the bowels of the engine bay a bit more. Man there are some clamps and hoses back there that would be a nightmare! I think I see how to drop the engine and I have a jack in my tiny garage so if it comes to it I'll be doing that <shiver>

 

I am going to test as well. I have new DVs coming but wonder if anyone has an opinion on this?:

I accelerate very hard and have what seems to be a sudden let down of boost or power for about a half second. then it comes back on but it is like a lurching or missing of power that is very alarming. No CEL's.

Should I be looking for bad DV or hose failures?

 

This hesitation is likely from plugs/coil packs. You will eventually get a CEL with code P30XX. How many miles since you last changed them?

Boost leaks aren't so intermittent.

Jon

 

They are likely original plugs...car has 31 k and is due.
Re: hesitation...not really intermittent. Car will do this everytime that I accellerate full and hold.

 

Hats off to AWE! I ordered my F-hose from them this weekend and it was on my doorstep this evening! :-O The SAMCO hose came complete with clamps oriented properly for install.

I've also gotten word from BL that my DVs will be to my door this before this week is out. Awesome service on both sides!

 

I began the process of pressure testing and found some clamps that felt loose. I decided to take my nutdriver and tighten all of them down without taking the time to test. Problem seems to be solved. I am expecting F pipe and DV from AWE today and will make the change proactively.

BLKMGK, do you have your new parts installed yet? After assessing the engine compartment and all the nightmares people have expressed about DV valve changing, I am going the (hopefully) easier route and dropping the engine a few inches first.
https://www.6speedonline.com/forums/...tt-engine.html

 

Okay, got my DVs today!

For those of you looking to upgrade DVs take a VERY close look at the stock ones before you begin. Note how close and crammed they are. See that FAT *** vac pipe that runs between them? Those nice shiny BEEFY billet DVs? They are BIGGER than stock. See the problem coming? My OEM DVs popped out quickly, the new ones going in... not so much! Bear this in mind when ordering...

So, an hour or two wrangling and they were done - hands all nice and chewed up too. The fat vac hose I tried shoving into the back - no go. It is indeed stuffed between the two DVs now but it was tough! It has a nub on it to keep from being rubbed through, I had to move that some. I stuck the back DV in first, added the F-pipe, squeezed in the second one, got the end of the F-pipe onto the intake piping. I did NOT drop the motor, I seriously WANTED to! If you can do this for the job do it, don't hesitate to get the clearance. The DVs end up pretty close to the top of the engine bay, mine are pushed up pretty good, be careful jacking it back up. I chose DVs that did NOT have nipples on top like stock, this is good to keep from crushing things when you put the motor back up...

FWIW I put pressure to the motor via the intake - no more hissing by the DVs! I do hear some hissing in the wheel well on driver's side though. I strongly suspect it's the intake piping though but it's not really bad - think my pressure gauge is crap so I saw no reading. Sadly after talking to some folks I have concluded that my boost issues are something going on with my boost controller. This was educational and I upgraded some things, likely stopped at least one leak, and will continue till I solve the issue and get past .8BAR but this isn't the fix for me this time

 

Today I found my second leak by the passenger side inter-cooler intake. The hose was gummed up and showed a leak. Cleaned everything up, re installed and no more leak. This is my second leak "find", after the slit in the F hose. Here is the question. The car has a Ruf kit on. Now the intake to the turbo's compressor side doesn't appear to be stock. I can actually move the hose from the compressor and feel a light clunking further up, presumably were it connects to the intake part. Behind the engine, but way up there! I took a look under the car but I can't really see how far up. From looking at a schematic of the engine, it looks like a real tough spot to get into. Any advice? Can I reach there without dropping the engine? I realize it is not a pressurized hose, but the movement is a little unsettling. Thanks.