K'netic
05-31-2012, 05:30 PM
I'm working on a friends Z with an STS rear mount turbo kit and I can't get it to make anything more than 4psi of boost.
It had an AEM Tru-Boost controller on it but when I adjusted the boost settings on it, nothing changed, so I disconnected it and put a TurboXS manual boost controller on it (and yes, I plumbed the vacuum correctly, not the same as the AEM controller) and gradually turned it up until the controller was about to come apart. Still no change.
Pulled the Tial wastegate off and took it apart. The diaphragm is in perfect shape and the piston moves up and down without any drag.
I plugged the top port on the wastegate and left the bottom port open to force the wastegate to stay shut and see if I could get the turbo to make max boost. It still only made 4psi at the manifold. After I ran it like that I felt the dump tube on the wastegate and it was still cold so I should have seen ~25ish psi, right?
The only thing that makes since is there's some sort of massive boost leak between the turbo and the throttle body.
After everything I've checked, the only thing left between the turbo and the TB is the Tial BOV. I've never really heard of a BOV closing fully when the car is idling or off but sticking open under boost.
I haven't been able to check it yet because the only way I can think of is to strap the car on the dyno and run it while having someone watch the BOV to see if it starts leaking under boost.
I took the BOV off and tried pushing on the piston and it took both thumbs and quite a bit of force to get it to barely move so I really don't think the charge pressure is enough to push that valve backwards (especially since the vacuum line on the top would be sending manifold pressure (boost) to the other side of the piston, forcing it closed.
I'm at a loss, I can't think of what else it could be.
Any suggestions would be greatly appreciated.
It had an AEM Tru-Boost controller on it but when I adjusted the boost settings on it, nothing changed, so I disconnected it and put a TurboXS manual boost controller on it (and yes, I plumbed the vacuum correctly, not the same as the AEM controller) and gradually turned it up until the controller was about to come apart. Still no change.
Pulled the Tial wastegate off and took it apart. The diaphragm is in perfect shape and the piston moves up and down without any drag.
I plugged the top port on the wastegate and left the bottom port open to force the wastegate to stay shut and see if I could get the turbo to make max boost. It still only made 4psi at the manifold. After I ran it like that I felt the dump tube on the wastegate and it was still cold so I should have seen ~25ish psi, right?
The only thing that makes since is there's some sort of massive boost leak between the turbo and the throttle body.
After everything I've checked, the only thing left between the turbo and the TB is the Tial BOV. I've never really heard of a BOV closing fully when the car is idling or off but sticking open under boost.
I haven't been able to check it yet because the only way I can think of is to strap the car on the dyno and run it while having someone watch the BOV to see if it starts leaking under boost.
I took the BOV off and tried pushing on the piston and it took both thumbs and quite a bit of force to get it to barely move so I really don't think the charge pressure is enough to push that valve backwards (especially since the vacuum line on the top would be sending manifold pressure (boost) to the other side of the piston, forcing it closed.
I'm at a loss, I can't think of what else it could be.
Any suggestions would be greatly appreciated.