What the hell does that little flapper door in the S4 TII manifold connect to?

 

it dont connect to nething. it's the wastegate man.

 

No, the wastegate's in the turbo, not the manifold...

It's the control flap for the twin-scroll system. One of the turbo's scrolls is blocked off at low revs to make the turbo spool faster. It should have an actuator connected to it, with a vac line on the actuator heading up to the solenoid rack.

 

NZ how do you know so damn much!!!???

 

Just curious, but where from the selenoid does the vac tube goto? the intake im assuming?

What rpm does the selenoid activate?
Without the selenoid, and if you routed the twin scroll actuator just to the intake, how early would it activate compared to use with the selenoid?

 

One of the post-throttle manifold nipples (it needs vacuum).

I thought it was 2,700rpm, but the Yamaguchi book says 2,500rpm.

It doesn't quite work like that. The solenoid allows manifold vac to suck the flap closed to low rpm, and then allows it to escape at higher rpm. If you connected the actuator straight to the manifold the flap would open as soon as you opened the throttle and then close as soon as you lifted off. The turbo would not be spooled any quicker than if the system wasn't there.

And it's solenoid, not selenoid.

 

well...I don't have anything hooked up to it. Where would the solenoid be located and how do I hood it up?

 

If you want more top end flow and dont car to loos just a little low end, take out the actuator and arm,cap the nipple for the vacuum line, and remove the flapper from the manifold to turbo side. now you will have a hole where the arm for the actuator passes through the manifold. You tap it with a 1/4 tap and put in a 1/4 plug with some locktite to make sure it never comes loose. That will allow you better flow but you will loose the function of the actuator. Its a small trade off for me I was willing to go for.

 

ah, ok, didnt read the question right. calm down....

 

gotcha, I had the system completley backwards in my head. So its vacuum that holds it open, and its vacuum sealed off in the tube by the solenoid (heh) that keeps it open under open throttle. The selenoid activates at a given rpm and the flapper door opens allowing more exhaust gas to enter the turbine.

Learn something new every day here, thank you.

 

The solenoid is on the vac rack with the others. If the rack in intact you're probably just missing the hose between it and the actuator. See the FSM for more detail.