1987 TII.

The Switching Actuator which looked like of an aluminum can with an aluminum vacuum line on one end and the rod connecting to switching valve on exhaust manifold.

Does this aluminum vacuum line feed into the switching actuator should be getting vacuum & pressure from an intake manifold?

I use the turbo gauge to test for vacuum / pressure signal on the vacuum line just ahead of the switching actuator, but the turbo gauge did not indicate any reading of either vacuum or pressure at all.

Thank you

 

It has a solenoid. It should only get vacuum (has a check valve). The vacuum holds it in place, and then at 2700ish RPM it "let's go". It's not really a boost switch, more of an RPM switch.

At "low" revs, it holds the twin scroll shut to spool the turbo faster, then at "high" rpm it lets it go to send full exhaust to the turbo.

 

Vacuum only, with check valve.

Thank you

 

I'm having low rpm issues seems really sluggish. How would I check to see if this actuator is working properly at low rpm?? Pictures of what I'm looking for would help if you got any. Thanks

 

It's hard to miss. Huge waste gate looking thing attached to your manifold with a banjo bolted vacuum line attached in the front

 

So basically the waste gate actuator? I have another S5 turbo on my bench and when I look at it it is slightly cracked open. Is that because it is at 0 PSIG? And is the waste gate what controls the twin scroll part I'm not familiar with how it all works other then when you reach boost level approx. 7 PSIG the waste gate should open by passing the turbo and going into the exhaust correct??

 

no
the top manifold, see the GIANT "wastegate looking thing"? the twin scroll is controlled by the twin scroll solenoid. part of the emissions rack under the oil filler neck. the line for it runs around the turbo heat shield and up and around to the solenoid. the wastegate is internal to the turbo itself. activated by turbo boooosts. twin scroll is activated by vacuum, or lack there of. at a certain RPM the twin scroll "opens" to allow full exhaust flow. otherwise it stays closed to help spool faster.

 

Okay makes sense. Now why does it look like one of those manifolds has it and one doesn't??

 

top is s4 bottom, s5

 

So I'm assuming this is it and it does go to the twin scroll actuator. Had my gf rev it while I watched and it is opening and closing. But lot of smoke seem to come out so I think I have an exhaust leak before the turbo which would cause bad lag correct??