Boost leak on boost controler

[Andrew7DG]

To start with I just got done building a manual boost controler that looks like this


http://www.geocities.com/chmwatson/FAQs/mbc.html

I did a boost leak test on my car to see If I had any remaining leaks.
If you look at the diagram they said to drill a hole. When I filled up the system this was the only place left that had air coming out of it. The smallest bit I had was a 1/16 so that is the size of the hole right now.
Is this causing a boost leak on my car and hurting performance? What should I do to fix it?

 

[DSM90AWD]

From the FAQ you post

The bleeder hole is not large enough to affect the signal to the Waste Gate but it is necessary to gently vent off excess vacuum or pressure in the line which causes a type of signal lock. If the hole wasn't put in, the controller would have difficulty controlling boost above about 15 pounds

This bleeder is needed, all ball/spring style MBCs have one, but you doubled the size of the one recommended (1/16 vs 1/32).

The hole in my old-school Hallman MBC is prol 1/64 as was the one on my Extreme MBC, so I'd recommend JB welding the hole you drilled and redrill the correct size

 

[skinnykenny84]

I was just schooled yesterday that when you do a boost leak test to back the knob all the way out or take off the boost controller......here you go


Originally Posted by skinnykenny84
So I changed out my MAF with a friends and my fuel cut problems went away, so I thought. After a day or 2 of driving it has returned like a s.t.d.

So back to the drawing board. I do a boost leak test again today and can only get about 6 psi on my gauge. Now Im using one of those weak a$$ air pumps that you plug into your cars lighter, its all I have at the moment. Well at 6psi the only leak I found is the vent hole on the mbc. But isnt that supposed to leak? Its just funny I never noticed it leaking before. Of course when I put my finger over the hole I cant find any other leak and it stays at 6psi for at least 15-20sec. Now I know 6psi is not enough to do much with.


You have to disable the MBC or turn it up to full before doing a boost leak test or it will leak thru that hole. Two things that have caused me to hit fuel cut were a boost leak, and having the SAFC too rich. I had to compensate for an exhaust leak that i had for a few days by richening the SAFC to like +13 or so on stock injectors, and it would cause it to cut above 15 psi, especially at night, because the SAFC tricks the ECU into thinking there is more airflow than there really is, so it cuts.

 

[skinnykenny84]

I meant to just show you the part about the mbc