diy mbc problem.

[1cleanGSR]

so i made my own boost controller... i didnt follow any write up i just found peices in my garage.. including the little ball and a bunch of springs

it looks good and it works.. kinda. i sealed all the threads too.

the problem is i adjusted to about 15psi (stock fuel, mods in profile) and it holds 15psi fine in 1st, about 14psi in 2nd, then only 10-11psi in 3rd, 4th, and 5th.

whats the deal? how does a gear affect boost control?

the only thing i can think of is maybe boost leak?? since i spend more time in boost in higher gears maybe it leaks more?? did i just answer my own question?

anything else it could be?

 

[ilikespeeding]

any other symptoms of a boost leak?

good time to check for shaft play and to see if your turbo spins freely.

 

[snowborder714]

Did you remember to drill the bleeder hole? Not sure if that would change it that much or not.

Here's a how-to on making your own if you need/want it:
http://www.geocities.com/chmwatson/FAQs/mbc.html

 

[1cleanGSR]

well now that i think about it, vacuum is a little low. about 12inches at idle... boost leak huh?

and no i didnt remember to drill that hole.. should i?

and tomorrow i'll check out the turbo, see how it spins and check for shaft play.

 

[snowborder714]

Yep, there should be a bleeder hole in there. Do that and do a boost leak test at the throttle body as well as the turbo.

 

[1cleanGSR]

ok. hopefully i can find a 1/32 drill bit.

 

[1cleanGSR]

well... i drilled the hole... then i had no boost control. the hole might of been a tad big. im not sure the size.. i know it was smaller than 1/16 but im not sure if it was 1/32.

it spiked to 20psi and blew off some intercooler pipingWTF

so i need to go get a new clamp tomorrow ### it stripped.

and i replaced the peice i drilled into so now its back to the same thing..

 

[proto2]

I would recommend changing the spring and replacing the housing then redrill the hole with the smallest bit you have. Mine is about the size of a sewing needle. If that still doesn't work just buy one.

 

[anteversion]

Yes its very important to drill a hole cause without it it wiil cause wastegate air lock. That means that the wastegate will get stock open and you will be not able to build boost correctly. By the way i highly recommended some great quality MBC like hallmark and turbosmart etc.... cheap ones produce spike and damage like you boots busted

 

[1cleanGSR]

i need to find a drill bit small enough.

i changed the spring tho and it holds 15psi good now.