only so much boost

[mrtheory]

hey guys, I just rebuilt my 95 gst engine and i have broke it in. It has a 14b, 1g bov, 1g cams and a few other things. My problem is i can't get past about 10lbs of boost. I can take the hose off the wastegate and floor it and still nothing past about 10psi. The turbine housing was not cracked, not much shaft play on the turbine. The car runs great but limited boost. The only thing I can think of anymore is a possible blocked cat or maybe a cam issue. I have hooked the air compressor to the turbo intake and searched for leaks and nothing substantial has show up. I would really like to figure this one out guys!

 

[TRSblader]

Have you adjusted the boost controller so that it will allow more than 10 psi?

 

[JEFFREYCASTGSX]

Do you still have the stock boost gauge, and if not where do you have it pluggged in? Those "substantial" leaks can also be the reason.

 

[stroked_AWD]

Boost leak test.

 

[project98dsm]

He said he has already performed a boost leak test...read the posts.

When you reach your peak psi, does your car stumble or stall out, and then stop once you ease up on the throttle some?

 

[mrtheory]

no, when the car reaches the max boost it just stays there, no stumbling or anything, it just wont go any further. when you are first accelerating it has a slight minor jumping till the boost starts climbing otherwise it runs fine.

by taking the hose of the wastegate boost should go through the ceiling, no boost controller needed.

I have tested for a boost leak and there is a tiny leak out of the throttle body and a little out of the wastegate but only a little.

 

[jayb903]

hey guys, I just rebuilt my 95 gst engine and i have broke it in. It has a 14b, 1g bov, 1g cams and a few other things. My problem is i can't get past about 10lbs of boost. I can take the hose off the wastegate and floor it and still nothing past about 10psi. The turbine housing was not cracked, not much shaft play on the turbine. The car runs great but limited boost. The only thing I can think of anymore is a possible blocked cat or maybe a cam issue. I have hooked the air compressor to the turbo intake and searched for leaks and nothing substantial has show up. I would really like to figure this one out guys!

Did this occur out of nowhere? And also why do you think it could be a cam issue? Kinda sounds like a leak out at the wastegate.

 

[the_mork]

If it actually leaks out of the wastegate actuator then it is probably dead and only putting minimal pressure on the wastegate flapper. Can you try a different actuator?

 

[TerribleTSi]

I doubt it is a cam issue. Sounds internally turbo or wastegate for sure. running a closed flapper makes me believe your flapper is not closing properly. Actuator check then pull your 14B for a more thorough analysis. Just don't cut corners.