Keep spinning young sky walker....This post is pretty silly as you were able to get the soft spring to hit 18 psi (so everything was installed properly)....Then you install the stiff spring (but don't turn the MBC) and cannot get above 11 psi and are concerned ...

Crank up the MBC and solve your problem....My guess is a simple 5 minutes spent adjusting your MBC would have eliminated this post.

Good luck, now get to work.

 

I continue spinning and am getting no where, I'll give it another go tomorrow when I'm free, it's late now.

 

So what does your boost gauge read when you turn your MBC out all the way counterclockwise? Maybe you need to increase wastegate preload.

 

keep turning it

 

What is your target boost? Let's just say that it's 21 PSI. So, if your base WG pressure is 11#, there are a couple of ways of increasing it ten more PSI. You can either leave your base pressure at 11# and crank down on your MBC till you finally arrive at 21#, or, you can preload the WG mechanically to 17-19# and dial in only the last few PSI with your MBC.

Now, the two methods outlined above both arrive at the same peak boost level, however, boost duty cycle will behave a whole lot different depending on which method you employ. One method gives significantly better turbo spoolup than the other with the added benefit of providing overall better flapper valve control.

 

Sparky -- That makes absolutely NO SENSE.... WG preload could be 1# and if the MBC were working he could still get boost...The WG see's NO air with an MBC until the MBC sees the pressure / airflow that is dialed in / established...

 

Sparky -- I don't want to come off as a D%&% but you are giving really bad advice. When someone changes the 'preload' as you call it on the stock WGA by shortening the rod, they are in essence not allowing the WG to fully open. The problem with this is that you will get a boost spike and then a long creep to like 6K and then it taper. This will cause all sorts of tuning issues and is 100% NOT what anyone should do.

For the OP -- It sounds like either your MBC is defective (I had similar problem with mine) and the knob is twisting on the thread that is intended to push the screw down. Unscrem the top and try adjusting a few times with pliers to ensure the screw turns...Then re-install the top, tighten down, and adjust MBC...Also, make sure that all lines are nice and tight (ziptied, etc.) and that you have no boost leaks. Good luck.

 

At between 17-19 PSI of preload there should be no bind whatsoever and the actuator rod/flapper valve will go through their full range of motion. In your particular case, are you really just running the 11# of base WG pressure w/o any preload whatsoever and controlling boost all the way up with just the stock BCS?

With the stock setup you might get close to bind if you try setting preload up over 23-25#.I personally have run up to about 21# of preload and there was no bind. I didn't want to tighten it anymore as I had peak boost set at 24# and was running straight 91 octane and I was a bit worried about spiking or overshooting on crappy gas. But it didn't happen to bind in my particular case. I think that you are worrying a bit much.

What do you mean when you say that setting WG preload to 17# will cause "all sorts of tuning issues?" The WG actuator, the actuator rod, and the flapper valve will sure go though their full range of motion at 17# of preload.

If you are running around with only 11# of base wastegate pressure(zero preload) and are using the wimpy stock BCS setup to keep the flapper valve on its seat from the base of 11# all the way up to your peak boost setting 0f 23.5#(or whatever), then I guarantee that you've got a crumby spoolup profile on your turbo because there is no way that the stock BCS is keeping that flapper valve on its seat after 11#.

 

I guess that we're even.... because I don't see where it is that you're coming from either. If you back out your MBC to all the way soft, you should be at base wastegate pressure of about 11#, if the wastegate's actuator rod is lengthened to where it just slides on and off of the flapper valve's pivot arm. At that point it would be physically impossible to set preload down below 11# to 1# as you suggest. You're just kidding, right?

 

cij911: I was thinking about your particular case. Maybe in conjunction with the stock BCS, an increase in WG preload is not a good idea. But, I wouldn't know since I don't use the BCS, prefering instead the more direct control afforded by an MBC. Perhaps too high of WG preload in conjunction with the stock BCS could indeed lead to tuning and boost control issues.

 

Sparky -- Shortening the rod does not change the preload tension. You are obviously not an engineer and are way off. The tension is the the spring factor and the WG is opened by a predefined pressure that pushes the valve enough to move the rod. Changing the rod length changes the degree at which the WG can open. If the WG does not open at all, you'd overboost. If the WG only opens partially throughout the entire RPM band (which would be caused by making the rod too short), then you will get a boost spike and then creep.

I have tested this with both the BCS and the MBC.

 

Yes, I am not an engineer. However, I still think that the stock BCS is the worst way to control boost and that if you use it, you are, at best, only able to control peak boost, which in and of itself is really not a remarkable accomplishment. So what if you have have lousy spool up compared to a turbo which is setup with a properly sorted WG that has more preload than the stock base 11 PSI?

I tried my XEDE controlling boost though the stock BCS and got rid of the BCS and zeroed out the XEDE's boost table. I prefer the simplicity of an MBC and the control over spoolup that a properly tensioned WGA provides.

With the stock BCS there is no accurate and practical way to impact directly on a turbo's spoolup characteristics. All you can do is set max boost. To actually improve spoolup you've gotta keep the flapper valve on its seat longer. And the stock BCS setup does a lousy job of this. Or maybe you've designed a way? I think I vaguely remember a oneoff system employing varied and assorted restrictor orifices in the vaccuum lines. It was you wasn't it?

Send me PM's if you wish to continue this discussion as we've taken this thread pretty far off course already. I won't be visiting this particular thread anymore. Sorry for the OT rant.

 

Sparky - As long as you post incorrect information folks that know better should correct...

Your statements about using a BCS or EBC to control boost once again reveal your limited understanding of how our turbo setup works. Read up in the advanced ECUflash section and you will find that an EBC setup is far superior to an MBC, but more complex to setup. The stock ECU / BCS with an inline bleeder can easily control any boost level throughout the power range (ala Vishnu and others). Furthermore, using the BCS and ECU, one does not need to worry about changes in climate, overboosting due to MBC malfunctions, and can avoid hassles in emission sensitive states like Ca.

Back to the OP -- Has there been an update with your situation? How did you resolve your problem?

 

Nothing has been resolved unfortunately. I keep cranking it clockwise, and you would have thought it would at leat go up a little bit, but nothing. Is there a "proper" way to install the heavy duty spring? The boost eventually started to rise with the spring that came with the boost controller, but I'm getting no results with the heavy duty spring. Thanks you advance again for all your help everyone.

 

Assuming there are no boost leaks either with your system or off the MBC lines, and that it is installed correctly, I would just swap out the MBC with another...Before doing so, just for giggles, switch the lines and confirm your installation...