JBJ

iTrader: (3)

Should the connection below on the TD05 be connected to something?
I'm running the dawes through a T piece from the manifold, but even so should this be connected.

Could it explain why in my other post I cant get over 0.5 bar?
https://www.scoobynet.com/general-te...r-problem.html

Thanks All

silent running

I would imagine that would give you a LOT of boost related problems, quite apart from the fact that you've probably got a constant whistling the whole time. That little outlet there is for the compressor side boost signal that, on every turbo ever designed, is supposed to feedback to the actuator and thus the wastegate. On a Scoob, as standard there is a boost solenoid system hooked up to it and there are a few different ways of plumbing it in, but one way or the other, its boost signal is fed to the actuator.

You could block it up I suppose, and take your boost signal from elsewhere e.g. the manifold, but the compressor outlet gives you a totally accurate picture of the boost the turbo is making. Hence why it's used to control the actuator because it's the fastest and most accurate boost signal there is.

JBJ

iTrader: (3)

Hi

Thanks I thought that might be a bit of a problem when I spooted it was disconnected.
As I'm using a Dawes Device which has been T pieced into the manifold pressure line, do you have any idea what the outler should be connected to ?

I'm guessing something has come off or maybe it was just blocked off, I didnt do it so I just dont know.

Thanks
Jon

silent running

Well if you focus just on the turbo for a moment, (and working from the basics) you can see your 'hole' where the compressor boost signal should be coming out from. That should have an L-shaped outlet pipe sticking out of it, some are a tight push fit, some are threaded, I can't remember which that should be, but it needs to be there otherwise you've got nothing to connect a vacuum pipe to.

Secondly on the left side of your turbo as you look at it you should see the actuator which is a metal barrel shaped thing, also having an L-shaped pipe sticking out of its front. At the back of the actuator there will be a metal rod connecting back to the wastegate which you won't be able to see.

The compressor boost signal outlet and the actuator can be connected in the simplest way by a plain piece of vacuum hose from one to the other. As soon as the turbo starts producing enough boost (often 0.5 bar) this will force the actuator to move, pushing the rod, opening the wastegate and therefore keeping boost below that particular level - basically like a thermostat except it works on boost. Apologies if you know this all already!

If you introduce a Dawes Device into this simple control setup, you can adjust the Dawes so that the actuator doesn't see the boost signal at all until it reaches your preset point i.e. if you wanted say 1.0 bar, you could set it for that and only at 1 bar would the Dawes open up, the actuator would see the boost and move, opening the wastegate until the boost got below 1 bar again, at which point the Dawes would close, making the actuator shut the wastegate.

So far so good. The problem is that on a Subaru, it uses a system involving a boost solenoid and pressure exchange solenoid as well as sometimes different restrictors depending on model year. This is all to give better boost control, but it makes things complicated when you start putting Dawes devices into the system as well. You also could have a three or two port solenoid, which makes the plumbing different again!

In general though, I'd expect the compressor outlet boost signal to be taken to the 'input' side of the Dawes, then the 'output' side to carry on to the rest of the standard Subaru boost control gubbins. I don't know why it would be connected directly to the manifold.