Still fighting to control boost

[tbonitz301]

So i was having some pretty bad boost spikes, and then i got a ball&spring mbc that works great. It helped spooltime, and it controlled boost very nicely until today. I had my boost set at 15psi, and it was rock solid. Held great everytime. So i turn the coarse adjustment out a little till i was at 18psi. So i get in and drive, and now i hit full boost at 18psi, and then it will flicker between 15-18 back and forth. There is a large power difference obviously.I want my 18psi to hold.I'm using the turboxs ball&spring hp version.Please help me out here is there some adjusting i need to do on the fine adjustment or what. Also my boost source for the mbc is in the j-pipe.

 

[Black_Bullet]

Does that MBC have a bleeder hole.

Those flunctations are abnormal, but its obviously something mbc related unless your
W.G. flapper is old and loose and and it could be opening and closing randomly.

My boost would drop off , and recently I shimmed my w.g. actuator and it seemed to steady out a little.
This is probably completely irrelevant to your issue, and a shimmed w.g. will cause pretty harsh boost spike and if you cant tune that out dont consider it, but if I were you id just play around with your boost controller some more .

 

[tbonitz301]

No it doesnt have a bleeder hole. I tried messing with the fine adjustment, but it didnt help much. I did get the 34mm flapper mod so maybe it blowing openat 18 and sealing at 15. Could i put a spring on my wastegate arm to help it stay shut if this is my problem. Or is the diaphram to weak to open the gate with a spring attached to it?

 

[tbonitz301]

Come on guys. Where did you go bullet?Also i thought i might add that the turbo has 200 miles on it.

 

[Black_Bullet]

No it doesnt have a bleeder hole. I tried messing with the fine adjustment, but it didnt help much. I did get the 34mm flapper mod so maybe it blowing openat 18 and sealing at 15. Could i put a spring on my wastegate arm to help it stay shut if this is my problem. Or is the diaphram to weak to open the gate with a spring attached to it?

The truely best option for anyone is getting an external waste gate, i need one myself

First of all, make sure you dont have boost leaks or anything weird going on with your setup.

But , if I were you, just ebay a stock flapper setup and toss the 34mm.
Its only going to cause you power lose when you start upping the boost and trying to really run that turbo... Hell its causing power lose now if thats truely the culprit.

You cant really put a spring on the w.g. arm like your thinking, but you can look into the Peepers w.g. mod. I was too lazy to try anything like that though, so I just shimmed mines.
(Putting a small washer on each of the 3 bolts that hold the w.g. actuator to the turbo.)

A mbc with a bleeder valve will probably help control boost a little better, but in the mean time you can TRY the shims as that will keep it closed longer and may not open to the full extent ( quicker spool, maybe more psi to redline,) so maybe it will remain at 18psi but if you do it im sure you will have to readjust your mbc settings.

Or shimming the w.g. may just completely over boost or spike too high. IDK, I got away with it because i just tuned my car for the heavy spikes and by the time i start getting up into some rpms with these cams, my motor is digesting too much air for my little 16g to maintain the high boost anyways.

Unfortunantly ,you probably just have to toy around with stuff till you find something that works...

 

[tbonitz301]

I'll guess i'll try messin with it a little more when the rain stops. I really wish i had the money for an external gate.I'm pretty convinced the wastegate is my problem i just wanted some more opinions. Thanks for helpin out

 

[rarson]

I'm not a fan of TurboXS boost controllers. I would try another MBC, see if it helps. A Joe P. MBC is only $45 shipped.

I've been running a Tial 40mm for years now on a small 16g. I love it.

 

[tbonitz301]

I tried the mbc on a friends car, and it works flawlessly. I'm goin external.OH YEA

 

[Black_Bullet]

Yea I run the Joe P.

All cars will respond different to different MBCs etc depending w.g.

Yea I suggest going external and putting the stiffest spring your comfortable with for being your
lowest boost setting. Later down the road you will need all the little tricks you can get to achieve maximum performance out of your turbo !!!