Will restricted Y-Pipe vacuum hose cause no boost??
 

I broke the vacuum hose (larger of the two) that connects to the bottom nipple on the Y-Pipe. I cut the broken/cracked part off, but it left the hose too short. I bought a plastic coupler and another piece of pipe to join the two together to make it longer. Small hose clamps were used to connect the coupler and hoses.

It's obvious that the plastic coupler has a smaller I.D than the pipes it's connecting together, and therefore probably restricting air passage. Vacuum diagrams indicate that this hose is pressurized.

After putting everything back together, I find out that I'm not able to Boost (nothing above 0). Although vacuum numbers are the same. The BOV is not ventilating properly (hardly) and is now making a different vent sound than before.

Does this pressurized hose have anything to do with Boost ?? Thanks.

The smaller hose goes to the pressure tank which causes the 2nd turbo to operate, so if you have them somehow swapped...

You can use 6mm or equivalent hose to replace that larger hose. It isn't part of the turbo controls.

Read the vacuum diagram again and you'll see the larger hose goes from the turbo to the intake manifold.

Regards,
--Ashraf

No. You've probably knocked something else off in the process. Check the hoses to the actuators just to the right of where you were working on the Y-pipe hosing (this assumes you are working from the passenger side of the car).

Thanks. The hoses weren't swapped. I just thought that by restricting the larger hose, it would affect Turbo boost somehow.

Thanks. Everything is in it's place. I jacked-up the rear tires last night and and turned on the car. Put the tranny in Drive and gave it some gas to boost the Turbos. Just as it's about to gain Boost, the BOV starts venting and starts making a loud whine. So it seems that the BOV is not working properly. That explains where all my boost is going.

Check the BOV vent hoses to be sure they are not cracked or leaking ahead of the BOV. Also check the BOV vacuum lines to see if they were knocked off while you were working elsewhere.

The BOV hose and vacuum line passed the pressure test. The culprit seems to be the BOV cause it's not able to hold boost. Thanks.

still no boost? That really sucks. I wish I could help you out with it but I have no idea what the problem could be.

If you have all the hoses conected and not cross, it should boost fine. I had a problem last night when my damn TCA acuator fell off the damn door and I got no 2nd turbo boost. Got me really scared.

You should check if your rods from the wastgate and pre-control are all connnected and the doors are fully closed.

Amel

Yeah, still no boost. All the Rods are connected to the actuators. All the vacuun hoses are in place. But I've narrowed the problem to the BOV. I just bought one from a fellow member and I should have it in about a week.

If that don't work, I'll take out my 1911 and my AR-15 have a little fun with the Motor :)

BOV is not a BOV.
It is an air bypass valve.
It will leak unless a few pounds of boost are applied to the control port...

However, they can leak, and if it leaks with pressure applied to the control port, then you have your culprit.

You should be able to build SOME boost, though, because I've blown the BOV hose clean off the Y-pipe and could still make 7psi.

Did you check the intercooler couplings?

Also make sure the plastic Y-pipe isn't cracked/broken.

It can/will separate from the plastic flange that bolts to the bracket on the engine and still hold in most cases...

Regards,
--Ashraf