What could this be? (Boost control related)

[VPrime]

okay, where to start....
I bought this manual boost controllor from ziggy (Busta boost controller), and i think from day one it never worked (defective mbc?) and i posted about it. I posted that originally it would give me unlimited boost, and the "knob" did nothing. well it turned out it was either the "knob" or a kink in one of the lines (i "fixed" both so i dont know which did it.)
And it sort of worked... It no longer gave an unlimited rating so i was happy. I assumed ti was a problem with my car and not the controller.

Any ways forward to a week ago... I thought i tried every thing to get the mbc to work.. but apparently i forgot to try switching the lines (i thought i did but my brother told me i didnt) so i tried. Well I got unlimited boost again witht he knob all the way out... then it blew one of my pipes off... put every thing back to gethor, and noticed that it would no longer boost an unlimited amount.

It now goes to like 12-14 psi and then it no longer boosts and the gauge drops to like 10ish and I can no longer hear the turbo "sucking" all i hear is a WOOOOOOOOOOOOOOOOOOSH....... (this is after it build the 12-14 psi).. then the car sort of kicks/lurches and it stays at 10... and if i try and build more boost, it does the same thing.

STILL with the controller in backwards (according to the instructions) I tried turning the knob, when i turn the knob so it goes in, i can only make 10-11.. so i guess it sort of works, but back wards...

I now have the boost controller disconnected and now justr unned the OEM boost controll solenoid, and it is fine. (11-12 psi)

Any ways just wondering
1)What could that wooshing noise be?
2)Why can I no longer build unlimited boost (i know its bad any ways... but isnt it worse that it can no longer do it?)
3)could my turbo now be toast? I dont get any smoke or any thing.




ps. i forgot, when i run a line straight from my turbo to wastegate i only get 10 or so PSI.

AND I DO have an aftermarket gauge.

 

[patty AT forge]

Do you have the MBC connected to the same line as your BOV?

 

[WillyC]

Sounds like the BCS and wastegate actuator are hooked up properly. The wastegate actuator when hooked directly to the pressure source should open right around 10-11psi. The BCS should control the boost to around 11-12psi. What you really need to do is go to Home Depot/Lowes or whatever and build a boost tester to use with a compressor. This will allow you to check for boost/vacuum leakes, test your BOV to see if its leaking (which if its a 2G then over stock boost is probably is), and test your MBC without having to subject the car to high boost levels that could damage your engine.

 

[majik2k5]

There could be numerous explenations for this, so I'll give a few.

1. When your pipes blew off and you put them back together and it stopped boosting uncontrollably, it sounds like something isn't tight and you have a severe boost leak. make sure you have everything tightened down good, and build yourself a boost leak tester if needbe.

2. There is a specific way to run the MBC to make it perform better. It's actually pretty simple. Most people will run a T-fitting between the BOV/Intake manifold line, which is how I used to have my MBC ran. Thanks to oldman though, I was informed this is a no - no. It can cause your BOV to flutter, your boost controller to become inaccurate, and possibly uncontrollable.

Here's what you need to do. You vacuum line between the BOV and intake manifold should be untouched and left as short as possible without any kinks. Then run a line from the compressor outlet elbow on the turbo to the bottom MBC nipple, then run the other line to the wastegate and presto, instant better boost control.

If for some reason none of these fix your problem, post back. We'll go from there.

 

[VPrime]

Thanks for teh replies.
I have the MBC running from a nipple ont he turbo and the nipple off the wastegate. (I actually just disconnected teh BCS and used those lines)

Any ways I think i fixed the MBC. i took it apart and found the spring to be on its side, and one of the ballbarings on the wrong side (according to a DIY homemade MBC that looks similar). I think it works as I can Lower to the stock 10PSI, and raise it to 12... than if i turn a bit more it does the woosh thing again (i guess i cant hold more than 12 psi...)

So im pretty sure i have a leak, ill have to check sooon, and report back with all my leaks

Thanks.

 

[daren_p]

If your running the stock t25 (looks like you are) its completely normal for the boost to drop off at the higher rpms just because the turbo is to small to keep up. When I used to run my t25 at 16 psi it would drop down to something like 12 by 7000 rpms. As for the woosh noise have to done a PROPER boost leak test? If not do one. While doing a boost leak test also verify that the bov isn't leaking. If the bov stays open when the turbo is spooling or under boost you will hear a loud woosh noise.