Re: UrQ low boost pressure

[quk@isham-research.demon.co.uk (Phil Payne)]

In message <s4263781.027@tamsconsultants.com> Andrew Finney writes:

> So in the never ending UrQ saga I decided to bite the bullet
> and assess the condition of the turbo. For those who are
> following I now only get 8psi of max boost from my TAP'd '83
> UrQ. Well, after many knuckle scrapings all the hoses were
> removed and........ just a tiny bit of oil coating the hose from
> the turbo to the intercooler, no metal shavings, no grit. Actually
> most of the oil in the hoses was at the other end, near the
> intake manifold.

Oil is normal.  Quite a lot, sometimes.

> I grabbed the turbo shaft and there was no
> play at all. The turbine spun perfectly smoothly, no grabs or
> rough spots. Conclusion: turbo is in great shape.

I know I _always_ scream: "Look inside the hose."  The reason is not that
it's a very common failure mode - it's that it's very cheap to check and
the potential saving is $$$$.  Sounds like you're OK, though.

> So can I test the wastegate by crimping off the pressure
> feed line and carefully accelerate?

Yes, but I would recommend attaching a separate (calibrated) boost gauge. 
Don't rely on the dashboard instrument for a test like that.

> Anyone have any thoughts as to why I no longer have full boost?

Will I sleep?

> What about the frequency valve, do these go bad on UrQs?

And affect boost?  Not on a WR.

> Checked the line to the VDO boost gauge, it
> holds vacuum so there aren't any leaks in the gauge line. It's
> OK to use the original gauge's feed line right? I had it teed into
> the FTCU line but I prefer this location, but showed 8psi max
> boost. Could the pressure be leaking from the differential lock
> knob, or is there a one way valve to prevent pressurization of
> the diff. vacuum lines? Any thoughts appreciated. Thanks.

Nah.  Very hard to imagine a leak from there.  And, if so, it only sniffs at it.

If your picture of boost is from the dashboard gauge, and you also feel like 
doing a "crimped off" test, then attach a separate boost gauge by tee-ing in
to one of the two parallel inlet manifold take-offs and do the test.  Meantime,
let us think. 

-- 
 Phil Payne
 Committee Member, UK Audi [ur-]quattro Owners Club