MBC or just boost creep?

[NskGenakuDuckie]

Either I am doing something wrong with my mbc, or i'm getting some massive boost creep. I'm really not sure which is the cause for the boost shooting up to 22+psi on my 50 trim.

Cliff notes: 50trim internal gate w/ all supporting mods, 3" turboback exhaust no cat........ controlled by the Dejon tool dual stage MBC.

Screw on the mbc is backed all the way out and the toggle switch is switched to low boost. I would floor it in 2nd and the needle on the boost gauge would just keep creeping up higher and higher. I then switched it to highboost thinking the screw must control the highboost, and floor it.... BAM all the way up to 1.5bar (22.x psi) and the IC pipe blows off. I think if the IC pipe didn't blow off it would've shot all the way up to 30+psi.

So here's the big question. TO LOWER BOOST, DO I TURN THE SCREW ON THE MBC "IN" MORE OR SHOULD I "BACK IT OUT" MORE?

 

[JessesTalon]

if it is the same ball and spring as the Joe P im thining of and my MBC then BACK it out for low boost... put in for more boost...

So for my MBC its about a half turn per PSI, (around that)

what kind of O2 housing.

how big is the internal wastegate flapper? upgrade to 34mm or bigger flapper... or port the wastegate hole....

Could be a faltly MBC, OR you have it in the wrong way... did you say it sticks to a certain PSI then climbs, or it just climbs all the time? Turn the MBC around, back the screw out all the way and check if the spring is caught, then put back together but so the spring is not pressed down very hard (a few turns)

 

[NskGenakuDuckie]

I have the stock O2

The wastegate is huge on the 50 trim, it's also adjustable, but I don't know how.

Does anybody with an internally gated PTE turbo know how to adjust the wastegate?

 

[leet]

The wastegate actuator rod should be threaded, if it's adjustable. I'd suspect the wastegate is the cause of your problems.

 

[92awddsm]

I would say the stock o2 housing is the problem. I had boost creep issues with my stock o2 housing with a b16g. Im sure the 50 trim will have the same problem, just worse. Try porting the o2 and see if it helps.

 

[NskGenakuDuckie]

Yea I'm going to try that once I have time to take everything apart. I just can't see how a ported O2 can make such a big difference, but we'll just have to see.

 

[J92EGSX]

a stock o2 housing can make huge boost creep problems even with a 16g, if u have a 50 trim i whould definitely get a new o2 housing or port yours, besides then when u take that off you can see your wastegate and test that too to make sure it is opening.

 

[NskGenakuDuckie]

Originally posted by J92EGSX
a stock o2 housing can make huge boost creep problems even with a 16g, if u have a 50 trim i whould definitely get a new o2 housing or port yours, besides then when u take that off you can see your wastegate and test that too to make sure it is opening.

Yea that's exactly what i'm going to do, I had no idea a ported O2 can make THAT big of a difference. I'm still suspecting there is something wrong with my wastegate, so I'm going to mess around with it to see if it's fully closed or if it's just stuck. Because I plugged the vaccum hose from the intake manifold directly into the wastegate. And it should read really low boost, but with my silencer off the boost is still shooting up to like 20psi and then creeps up and up and up as rpm goes up. With the silencer on it holds 14.7 rock steady though.

So technically with boost controller or no boost controller the car still acts exactly the same way. So that makes me wonder if the wastegate is whack. I'm pretty sure I got the boost controller hooked up right.

 

[J92EGSX]

ok if your pulged the hose going from your manifold vaccum port to your waste gate, You should never be opening your waste gate because you have no pressure to push your rod thus open your waste gate flange. there for when you plug that hose you should be running full boost of your turbo. 20+ psi on a 14b. hook up a hose from your wastegate to your turbo out let pipe nipple, plug off all other manifold vaccum sources that are open, go run your car and you should only see about 10 to 11 psi, on a stock 14b acuator. with with exausht though this might be around 14 psi. If it does however show a steady boost level that is under 17 psi you know that your wastegate is operating. It seems like your mbc is not hooked up right.