I have a stock 89-91 turbo on my car and have a question about the vacuum lines that go to the wastegate actuator.

The little rubber hose runs from the wastegate actuator to the metal tube connected to the turbo itself, then to another rubber hose that connects to the turbo dishcarge (that connects to the intercooler).

My question is this, on the metal tube that is between the 2 rubber hoses in a metal nipple that stands straight out.

Should this be connected to something, capped, or be left uncapped. I am boosting way too high.

Thanx in advance.

Michael

 

That nipple should go to the wastegate control solenoid, which vents the pressure back into the intake when open. If it's just venting to the atmosphere like yours, then no pressure is reaching the wastegate actuator and the WG isn't opening, so you overboost. If you just cap the line, it will make less boost than stock, since the WG controller's job is to make the WG open later. If you have a FCD installed however, the WG solenoid won't do its job since you're tricking the ECU into thinking the boost is lower than it really is.

Make sense?

edit: wait a sec... you're using a S5 turbo on an S4 car? I think the S4 didn't have the WG solenoid.

 

That is a tee that leads to the S5's boost control solenoid. Your S4 will not have this solenoid so the open line must be capped.

Probably because the wastegate is seeing no boost pressure due to that open line...

 

I capped that line and it works fine now. I am new to the Turbo world and this is a TII swap that was done recently. I had no idea this needed to be done. Live and learn I guess. I am lucky it did not pop.

Thanx

Michael