Air Shrouded Injectors (and low boost)

[Mike_Buckham at ptk.pioneer.co.uk]

Thanks for your reply, Ken.

If the air ends up in the cylinders then I definitely shouldn't be losing
any boost through the injector air supply tube. My wastegate spring seems
fine. Though I don't have another spring to compare it with, it is not
broken and seems to apply a plentiful pressure against the wastegate shaft.
There is plenty of easy free movement in the wastegate shaft and the
diaphragm is not leaking.

The rushing air noise I can hear is exactly the same and seems to be coming
from the same place (though quieter) as when I suddenly release the
accelerator and there is a rush of air from the wastegate. I have checked
the "michelin man" hose and it is fine. I have also checked the hose from
the turbo to the intercooler, though not the intercooler itself. I am
fairly sure that the rushing air is from the wastegate or somewhere close
to the wastegate due to the noise that I can hear. I don't have an analog
boost gauge. I have been relying on the digital gauge in the dash, but in
this case it seems adequate.

Is it possible to be losing boost through the wastegate even if the shaft
is not stuck open and the spring is working fine? Is there an adjustment
which could be made to the wastegate shaft somehow which might be stopping
the wastegate from closing properly? Perhaps my wastegate is never closed
for some reason.

Cheers, Mike.




                    <auditude at cox.
                    net>                 To:     quattro at audifans.com, Mike_Buckham at ptk.pioneer.co.uk
                                         cc:
                    20/02/2003           Subject:     re: Air Shrouded Injectors (and low boost)
                    22:23






1.  Into the cylinders and then burned and finally out the tailpipe.

...

I'd be curious to know the condition of your wastegate spring.  Perhaps
it's weak or broken, or the shaft is bent and it is stuck open somehow.
You should be getting unlimited boost otherwise.

But then again, if you actually hear the sound of rushing air, I think that
is likely to be boost that is being created and then is being leaked out
somewhere.  Have you removed your "michelin man" hose (from the intercooler
to the throttle body) and closely inspected it for leaks?  Hold it between
your hands and compress it to see if it holds pressure?

Perhaps there is a leak somewhere else.  I would think the sound of a leak
would be leaking boost, not exhaust rushing past the leaking wastegate.  Do
you have an analog boost gauge?  Where is it hooked up and what does it
read when this happens?

Good luck,

Ken