Boost Control Issue

[XiKeiyaZI]

When I first began running this car, I was able to produce upwards of 23PSI, that of which I turned down via the SB Boost Controller that it was equipped with. I lowered it to 17PSI and sat happily there. Since then, I have replaced a leaking 1G Crushed BOV with a perfectly good condition 1G BOV, Uncrushed. I also tapped the turbo compressor outlet for a barbed nipple so I could run a dedicated line from it, to the MBC, and to the Wastegate. The total distance of hose is about 2 feet as I have the MBC mounted near the intake filter. All boost leaks have been taken care of and accounted for, boost response is much better since I fixed the hose issue as the Wastegate line was T'd off of the BOV line, and I've got everything lined out, vacuum wise, as it should be. I'm still running into a singular issue : I can't hit over 17PSI.

I have tightened the MBC a full turn, checked my BOV, checked lines, performed BLT's, and have come to only a couple of possibilities. I have an adjustable WG arm so I'm wondering if somehow it was able to turn a bit to not allow the flapper to close completely. What would the likely hood of this be? I'm sure it wouldn't hurt to check, but I just can't see that happening, in all honesty, as the arm would have to come off of the flapper in order for it to be adjusted correct?

The Turbo in question is a T04B, laggy crapper that doesn't see boost until over 3700RPMs. It's internally gated, of course, and has zero shaft play. The only other thing I can thing is that I either have a bad Boost leak somewhere that I've missed or a blown HG, which I've been showing absolutely no symptoms of..that being loss of power, coolant, oil, or mixing.

 

[brian9397gsx]

I know my 1g stock bov wouldnt allow me to hold anything over 17. When your doing your blt its not leaking? I really find that hard to believe .

 

[XiKeiyaZI]

I know my 1g stock bov wouldnt allow me to hold anything over 17. When your doing your blt its not leaking? I really find that hard to believe .

Well, believe it or not, 1G BOV's have been known to hold over 20PSI. The first BOV that was on it would leak under any pressure. This one holds pressure as it should, well above what the old BOV would. Also, considering that on my 1G GSX I was able to press 18PSI on the stock BOV, I can't bring myself to believe that the BOV is my issue.

 

[GRAVEDIGGER]

Take the wastegate arm off the flapper and see if the flapper will go closed any more compared to where the arm currently has it adjusted. If it doesn't seem like it's closed all the way adjust it until it is closed.

 

[XiKeiyaZI]

Take the wastegate arm off the flapper and see if the flapper will go closed any more compared to where the arm currently had it adjusted. If it doesn't seem like it's closed all the way adjust it until it is closed.

Yeah, no brainer, I know...but I just can't bring myself to understand how it went from being fine to...not fine in a couple of weeks. I suppose that the WG could have had something funky going on with it and after a bit of use, the arm extends a tad bit further than usual. I'll do that when I get home.

I suppose what I'm looking for is other potential issues in case the WG arm isn't the issue.

 

[bastarddsm]

Here's how to fix any boost control related problem:

1. Get an External WG
2. Hook a line from the outlet directly to the bottom half of the WG.
3. T into that line and run it to a mini air pressure regulator.
4. Run line from outlet of Mini Regulator into the top port of the WG.
5. Adjust boost with knob on regulator.

You will now have rock steady boost control.