So I just got my car back from my mechanic and it is running great (new fuel, ignition, ast and turbos). However I noticed that I am not pulling more than 3-4 psi while my boost controller was set to 12. I noticed that a vacuum hose has broken off of the plastic turbo elbow that connects the intake to the primary. See pictures. Can this be the cays of not hitting 12 psi or is there more likely a different problem too?

In the picture you can see the hose w the clip in the middle just hanging, not connected. Also, does anyone know what it leads to? I couldn't tell based on the vacuum diagram.

Thanks

 

I'm willing to bet so, it looks like the bottom nipple has broken off the little plastic elbow there. Should 2 hoses running to it, not just one.

 

ya it goes right there behind the bigger hose, the nipple is broke. i have one for sale if ya need it

 

It's broken off the primary turbo inlet elbow. It is NOT the cause of your boost issue.

It's either the PCV vent or the vent for the boost control - both are just venting to pre-turbo filtered air.

You probably have a boost leak somewhere.

Dale

 

Dale, just out of curiosity, how can you be sure that this is not the cause of the boost issue?

 

And wouldn't a hole in the inlet elbow create a boost leak? Since air is just escaping?

 

There is no pressurized air in the INLET (vacuum) tube. Your boost issue is some where else.

 

Because I know my vacuum lines .

Due to federal emissions laws, any evaporative emissions - this is fuel or oil vapors - can not be vented out to air. They have to be burned by the engine and scrubbed by the cat.

Those 2 vacuum lines are -

- PCV, positive crankcase ventilation. It vents fumes from the oil pan, has to be burned by the engine.

- Stock boost solenoid bleed off. With aftermarket boost controllers you bleed boost pressure off to atmosphere. Again, we have to put this back into the engine to burn it.

One thing that many people have a hard time understanding is the air in the turbo inlet ducts are ATMOSPHERIC PRESSURE. Not vacuum, not boost. Yes, the engine is sucking air in, but it's not enough to cause a real vacuum.

Think of it this way - go into a bedroom and close the door. Take a HUGE fast breath in. Did the walls of the room suck in and collapse? No. The engine is drawing air from the outside world, that's a huge reservoir of air to pull from. The only way you have a vacuum is to have a restriction, and if you do, that means that something is blocking airflow to the turbos. If you had a totally clogged stock air filter in a stock airbox, maybe.

Anyhow, most common culprits for low boost, especially if it was fine, turbos were swapped, and now it's not, are either boost leaks from couplers not on well or not clamped down well or vacuum lines that were hooked up incorrectly that control the sequential system.

Dale

 

Thanks the that Dale, its really helpful. I think I ended up finding the boost leak. I have a split in my rubber IC hose. That seems to be much more likely of a reason.