Over Boosting? Need some help guys

talonsway · 03-29-2015

Started out with a manual boost controller that came on the car, pretty sure its a ebay brand and a Bleeder style. Threw that in the trash and started over.

Got a Halman boost controller. Taped the compressor housing on my 16g, ran that to the bottom port then the side port on the boost controller to the wastegate.

The problem that i am seeing with both boost controllers is that the boost will keep going up all the way to 30 pounds ( Max psi my gauge reads ). Its dependent on throttle, so if i hold it at half throttle or so it will hold 15 pounds then if i go to the floor it will just boost to 30 or what ever. It wont hold a certain boost, it will fluctuate with the throttle.

With that said i was curious of the wastegate spring, The previous owner did a bunch of stuff wrong and so i thought i would start there. Hooked a vacuum line to the waste gate port. Hooked a regulator on a air hose and slowly gave the waste gate some air to see when the arm would move. Started moving around that 10-12 pounds of air.

So then with my Halman boost controller, i left the side port that goes down to the waste gate port connected, took off the line that went to my compressor housing but left it attached to the boost controller side, put my air compressor onto that line to act as the boost source. I then spun the controller all the way out so i should go off the waste gate spring (10-12 pounds). I gave it air to see when the arm would move and i could not get the arm on the waste gate to move. After thinking for a while i noticed that on the side port of the boost controller there is a little hole on the port, like a vent to relieve pressure. Problem was that with it venting so much air i could not get the arm to open the flapper. So i went and got a standard barb fitting that went into the boost controller that didnt have a vent.

I threw this all together and no change, i drove the car and had the same results i cant hold a certain boost it goes every where. I would really appreciate some input. What makes me think is why i had problems with the halman boost controller i shouldnt need to be swapping the fittings on it? I must be over thinking it.

Thanks for reading

**Kracka** · 03-30-2015

The little vent is there to bleed off boost pressure when you close the throttle so the wastegate can shut, the barb needs that little hole in it for proper operation. Sounds to me like you might have a serious case of boost creep. Is the wastegate passage ported? Does it have the larger 34mm flapper or the standard (29ish)? What o2 housing is on the car? Did you use all brand new vacuum lines on the boost controller?

**Shane@DBPerformance** · 03-30-2015

Run the car with no boost controller. Just a line from boost source to wastegate. If it still goes too high, then try a different boost source, like intake manifold. If it still goes too high then you have a bad boost creep problem or the wastegate is broke.

talonsway · 03-30-2015

Quote:

Run the car with no boost controller. Just a line from boost source to wastegate. If it still goes too high, then try a different boost source, like intake manifold. If it still goes too high then you have a bad boost creep problem or the wastegate is broke.

Ill start with looping the vacuum line from the compressor housing to the waste gate that was my next step. Previous owner had the boost source from the intake manifold but during my research i read it was better to draw the source from the compressor housing? If i find out that looping my lines controls the boost what does this mean? that i have a bad boost controller? or my wastegate spring is bad. When i put air to the wastage its self, it activated the arm around the 10-12 pounds.

Quote:

The little vent is there to bleed off boost pressure when you close the throttle so the wastegate can shut, the barb needs that little hole in it for proper operation. Sounds to me like you might have a serious case of boost creep. Is the wastegate passage ported? Does it have the larger 34mm flapper or the standard (29ish)? What o2 housing is on the car? Did you use all brand new vacuum lines on the boost controller?

Ill put that fitting back on, i figured it was there for a reason just thought i would give it a shot with a different fitting. Wastage passage is not ported, and it has a 29ish? flapper. I have not got into any of that stuff yet so I'm going to assume its all stock. And stock o2 on it for sure. It has all new vacuum lines and no boost leaks.

**Kracka** · 03-31-2015

I'm starting to think your MBC might be bad. If you're local, DB sells a cheap, effective, generic MBC that quite a few of us have run over the year. I've also had great luck with the basic Joe P.

talonsway · 04-02-2015

looping the lines from the compressor housing to the waste gate fitting didnt do anything. Boost still goes with how much throttle i give it. Dont really know what would be causing this? It cant be my new hallman boost controller its a simple ball and spring.

**asshanson** · 04-02-2015

Wastegate stuck? Or your tapped boost source isn't providing what it should...

**goodhart** · 04-02-2015

If it's looped from wastegate to comp housing it can't be the mbc. I'd check Watergate preload if it's adjustable, or see if it's stuck shut.

**asshanson** · 04-02-2015

To rule out boost creep, you could unhook the wastegate flapper so it's open all the time, and see what your max boost at redline is.

talonsway · 04-03-2015

When i tested the waste gate to see what size spring was in there. I hooked up my air compressor to the waste gate port, ever so slightly watched the gauge on the compressor as i slowly turned it up and at about 10-12 pounds the arm moved, then slowly retracted. I will be unhooking the waste gate arm to see if there is a possibility the flapper is stuck shut. But if i find out that it is not stuck shut and is moving correctly my next step would be go to the intake manifold for the boost source. Is that a good start? This is starting to really confuse me

**Halon** · 04-03-2015

Yes, perhaps your tapped compressor housing job is no good. Try a different boost source.

talonsway · 04-03-2015

alright ill go to the intake manifold for the boost source and ill plug the compressor housing hole. Ill let you guys know how it goes!!

**Shane@DBPerformance** · 04-03-2015

There is more boost at the turbo than at the intake manifold, so going turbo can help lower the boost. But intake manifold is more consistent for changing conditions and better for holding higher boost. Sometimes a boost source right on the turbo does not work though. But its a 16G on a DSM aka guaranteed boost creep. Usually it just creeps to like 21psi though.

talonsway · 04-04-2015

well I wanted to hold 15 maybe 20 pounds. So if I could get it to hold around there I would be happy. Might just start saving for a external waste gate set up, just drive it like it is because I can not figure out why this is happen. My friends DSM with his 16g and he only boost like 12 and it holds perfect

1990GSX · 04-04-2015

Quote:

Originally Posted by asshanson

To rule out boost creep, you could unhook the wastegate flapper so it's open all the time, and see what your max boost at redline is.

Did you try this yet? If it still creeping that means your not able to vent off enough exhaust fumes through the wastegate exit to keep the compressor from still building boost.

This would eliminate both the mbc as the source and the wastegate.

**Halon** · 04-04-2015

You cannot figure out why? Have u tried the 2 tests that were mentioned?

talonsway · 04-04-2015

If I unhook the wastegate arm to the flapper it wud just be closed ? It wudnt stay open. I took the arm off to see if it was stuck. And it moves free but is this what I should do just take the arm off so it's open when I boost ?

**Halon** · 04-04-2015

Yes. You unhook the WG flapper and force the flapper so its just open, that way you forced it to bypass as much air as it can all the time. So your boost should be as low as it physically can be. Then you see if its still over boosting. If it is, then you know the issue is the wastegate just physically cant do any better and is your limiting factor. if the over boosting goes away, then you know the wg itself is not the issue and for some reason its just not getting told to open because you just proved that if its open it was nt overboosting, which is then why you try another boost source because perhaps there is some unforseen issue with the spot you are using now.

talonsway · 04-04-2015

Thank you guys a lot I'll let you guys know what happens !

talonsway · 04-04-2015

so i removed the arm and took it for a drive, at about 4-5k i was seeing about 20 pounds of boost and at about 6/6.5 almost 30 pounds of boost. So if i am thinking right this means i found the problem, and that is that my waste gate is bad? So start shopping for a big 16g Waste gate actuator?