Boost?????

[jhines]

I have recently began to fix some problems the previous owner of my car created. I put on a EVO 16G, O2 housing with full 3.5" exhaust and no cat. But he had removed the stock bost controller(hence the blown t-25), but I now have a manual turboX's boost controller. Yet I still cannot control boost pressures, at all!!! All turbo parts are brand new from SBR with a 14lb. wastegate spring. The spring will open the wastegate when you manually apply pressure, my vacuum is 17" at idle, and I have no known leaks on either side of the turbo. Does anyone have any idea why I may be having trouble and having absolutely NO boost control? This thing has me puzzled and many of my fellow turbo buddies wandering too.......any help or ideas would be appreciated greatly.....
thanx,
-Hines

 

[oldman]

It's asking me to log in, can't you post the picture here? Do you have the Turbo XS standard or HP version?

 

[jhines]

hey oldman, the pik format is not cooperating with me, so i'm just gonna post it in my profile, give me like 2 minutes and it should be there......and i just bought the standard boost controller, but i haven't used it yet.

 

[oldman]

hey oldman, the pik format is not cooperating with me, so i'm just gonna post it in my profile, give me like 2 minutes and it should be there......and i just bought the standard boost controller, but i haven't used it yet.

No need for the pictures, as long as you're sure you have the standard version.

1. Actuator fitting goes to the fitting inline but opposite to the adjustment knob.

2. The other fitting on the mbc goes to the J-pipe fitting.

3. To turn the boost all the way down, turn the the adjustment knob all the way CW.

I do suggest holding off on installing the mbc until we figure out what the problem is, it will just complicate things.

 

[jhines]

Yea, that's they way that I have always hooked them up....pressure side in and wastegate out.......but this pic is different. Since it won't upload, I'l describe it to you.

Outlet goes to the wastegate, of course. But the inlet pressure is coming from a T-split of the bov and the intake manifold tap.

So that is saying to get the pressure that reaches the intake. But in most cases, that pressure reading is gonna be lower than the reading at the j-pipe right by the turbo compressor outlet, right? So in my case, if I were to run that routing on my car, with the upgraded lower intercooler pipe, but the stock "webbed" upper pipe, I would lose at least 3-4 psi probably, right? Just wondering on your input b/c my buddy sent me this from an article that is very nice about boost creep on DSM cars that have done the 16G swap, as I have.
Thanx,
-Hines

BOV -> T <- Intake Man. ...........my own little pic for you
I
I
[ ]MBC
I
I
[ ]Wastegate

 

[compression]

3. To turn the boost all the way down, turn the the adjustment knob all the way CW.

on a ball and spring mbc you should turn the knob all the way ccw (counter clock wise) to loosen the spring and make it easier for air to pass to the wastegate acuator instead of tightening the spring and restricting the flow, right?

 

[oldman]

Is this picture specifically for the TurboXS Standard MBC?

 

[jhines]

No, it's just specifically MBC routing....not to my controller, says all mbc the way it is reading

 

[oldman]

So the T on the BOV line goes to the fitting opposite but inline with knob and the other one goes to the actuator?

http://www.dsmtuners.com/forums/attachment.php?attachmentid=46910&d=1108474460

 

[oldman]

on a ball and spring mbc you should turn the knob all the way ccw (counter clock wise) to loosen the spring and make it easier for air to pass to the wastegate acuator instead of tightening the spring and restricting the flow, right?

You're right, but he has the TurboXS STANDARD MBC which is a bleeder type mbc, no springs. The more you turn it in (cw), less pressure it bleeds off, the more pressure the actuator sees, the quicker the flapper opens, the lower the boost level.

 

[jhines]

yep, that's pretty muct the same pic.....so is that correct instead of going off the nipple i have in my piping from the compressor to the intercooler?.....i have the SBR 16G install kit with there j-pipe and piping.

 

[oldman]

yep, that's pretty muct the same pic.....so is that correct instead of going off the nipple i have in my piping from the compressor to the intercooler?.....i have the SBR 16G install kit with there j-pipe and piping.

A. That is not for you, it's for a ball and spring type mbc. Like I said in the above post, the TurboXS standard is a bleeder type. Your in and out fittings are reversed compared to the picture.

1. Actuator fitting goes to the fitting inline but opposite to the adjustment knob.

2. The other fitting on the mbc goes to the J-pipe fitting.

B. Taking the pressure source from the j-pipe fitting has many benefits.

1. The main reason why a lot of mbc instructions and some tech articles suggests to tap from the BOV line is because it's connected to the intake manifold, the argument is that this is more accurate because it's the same pressure the engine sees. In reality this is a non issue because the boost gauge is tap to the intake manifold no matter where you tap your mbc so there is no advantage in tapping the bov/manifold pressure as previously thought.

2. The proper functioning (opening and closing) of the bov depends greatly on the accuracy of the pressure in the vacuum hose you're thinking of tapping on or off boost so it's best to leave it connected directly to the manifold without any interference.

3. Tapping off the compressor/j-pipe offers the shortest vacuum hose route which greatly reduces the chance of boost spike.

4. In the case of boost leaks, tapping off the compressor/j-pipe will help prevent over boosting the turbo.

5. Hooking up a bleeder type mbc like the TurboXS standard mbc to the bov line will result in a vacuum leak as well as affect the working of the BOV.

 

[punishercb]

Okay, I don't feel like reading the entire page, but are you sure that you adjusted the MBC right? When I first installed my MBC I didn't set it right and it shot to like 25 psi. I just screwed the MBC all the way down and then backed it off from there. Then when I started seeing the boost increase, it only took like a half of a turn on the mbc screw to change the psi like 2-3. Anyways, I hope you guys have alread ruled this out but I just thought I'd toss in my .02. Good luck.

 

[jhines]

punishercb, yes i have already considered that....it was my first thought, so i took the mbc out of the setup completely and tried to run straight pressure from the j-pipe to the wastegate. That means that my boost control should kick in at 14psi b/c the EVO III wastegate springs are rated at 14psi, but it still does not. That's why we are expecting something with either the angle of that wastegate, or the O2 housing......something with that part of the system. But thanx for the input anyways.
-Hines

 

[compression]

You're right, but he has the TurboXS STANDARD MBC which is a bleeder type mbc, no springs. The more you turn it in (cw), less pressure it bleeds off, the more pressure the actuator sees, the quicker the flapper opens, the lower the boost level.

ah ha =) i can see where that could confuse some people.. and if you absoultely cannot get it right might i suggest that you buy a 7$ <b>BALL AND SPRING</b> type mbc from ebay (thats where i got mine from)

 

[jhines]

That would be a logical suggestion compression, but I have already said that my problem is not my mbc.......I know how to hook mine up. I cannot control boost...period!! Not with the wastegate, so how is buying another mbc, just another type, gonna help me out any? Thanks for the tip, but I have already stated several times in this article that my problem is not the mbc.
-Hines

 

[jhines]

oldman, I figured out that the 20psi hit is around 6000-6500 rpm in 2nd and like 5500-6000 rpm in 3rd. But now I have another problem, so I'll just port the turbo out completely and do some other minor porting when I put my 6-bolt block in. But is that still just considered VERY BAD boost creep? If you want, I am about to post a thread on swapping a 6-bolt block into a 2G using the 2G head.....I'm sure that you know the answer as to what all I have to do in order to swap that, so you can answer that thread to if you'd like. Thanx for all the help.
-Hines

 

[oldman]

Porting for boost creep you said?