UrQ low boost pressure

[Andrew Finney <afinney@tamsconsultants.com>]

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. 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 do need a
new intercooler to intake manifold hose though. Mine's getting
very tired looking. Pulled the spring off the wastegate. No tears
in the diaphragm. Are there supposed to be washers under the
spring? Must be more of the same washers I took out when I
put the TAP spring in (previous owners attempt to gain a few
HP). So can I test the wastegate by crimping off the pressure
feed line and carefully accelerate? Anyone have any thoughts
as to why I no longer have full boost? Hoses seem good, good
diaphragm, good turbo, maybe bad spring but I don't think so,
bad wastegate? What about the frequency valve, do these go
bad on UrQs? 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.

Andrew Finney
1983 UrQ.