wastegate or mbc?

[gsxin]

Ive been having a boost problem for a while now and I think Ive narrowed it down to what it could be. I cant get more than 11lbs of boost with my mbc turned all the way up. today I unhooked the air line that goes to the wastegate actuator and quickly made over15lbs. can a bad actuator do this?

 

[gsxin]

to be alittle more in depth... I disconected the mbc from the actuator making the wastgate stay closed. this elimated the possibility of a huge boost leak. also the turbo spools up fast just cant get past 11psi

 

[oldman]

It's the MBC not the wastegate. Which MBC and how is it hooked up?

 

[Matrixhunter]

I have the exact same problem right now. I am using a turboxs boost controller car just won't boost past 11psi

 

[oldman]

I have the exact same problem right now. I am using a turboxs boost controller car just won't boost past 11psi

1. Do exactly what gsxin did, test run with the actuator fitting open, make sure to pay close attention to the boost gauge as out of control boost is to be expected. If you're able to boost past 11psi, the problem is the MBC or the way it's hooked up. If problem persists, report back.

2. How and where is the TurboXS connected?

 

[Jeff822]

I have the exact same problem right now. I am using a turboxs boost controller car just won't boost past 11psi

My buddy had a turboxs MBC and was having the same problem not being able to boost over 10-11 psi, ditch it and get a Hallman.

 

[Generation X]

1. Do exactly what gsxin did, test run with the actuator fitting open, make sure to pay close attention to the boost gauge as out of control boost is to be expected. If you're able to boost past 11psi, the problem is the MBC or the way it's hooked up. If problem persists, report back.

2. How and where is the TurboXS connected?

I know this thread is a few months old but I've been having problems with my boost as well, mainly being slow spool with an internally gated FP Green. When I disconnected my line from my wastegate actuator it would spool slow and it would only go to about 20psi and that is it. I was expecting it to be out of control but that wasn't the case.

So... I've done boost leak tests to about 20psi, which generally take about 3 minutes to slowly leak down. I've checked my compression which is good, and I have seafoamed my motor to see if I had any pre turbo exhaust leaks. I'm thinking I may have a bad wastegate actuator but I'm not sure. I've also run a line directly from my boost source on my lower IC pipe straight to the wastegate actuator and it hit and maxed out at about 14psi, but I got that 14psi by 4000 rpm which is about right considering I have cams and a 50 trim.

But.... when I hook my hallman mbc right back up to try and run 20psi it takes a agonizing 5000 rpm to hit that full 20psi of boost. Do you think I may have a bad actuator? I've checked the wastegate flapper and it's all the way to the left torwards the passenger side if your standing directly in front of the car. I've also ordered a new exhaust manifold gasket, and a new 7cm gasket to swap out. I still have about 6 months left on my warranty for this turbo but I'm trying my best to make sure it's not anything else other than the turbo itself. Thanks for any advice!!