[urq] Re: Upper Wastegate Hose on '83 Ur Quattro

Buchholz, Steven Steven.Buchholz at kla-tencor.com
Wed May 5 21:41:26 EDT 2004

... are you still seeing 1.9 bar manifold pressure?  If so, that is probably
why your FP is shutting off.  I just checked the IST docs ... they indicate
that for any RPM at or above 2500, a pressure of 1.9 bar will shut off the
fuel pump.  At RPMs lower than 2500 the ECU will shut the FP off at even
lower pressures ... down to a minimum of a shade over 1.2 bar at 1000 RPM
and below.

Someone may have cranked down the adjustment on the WG spring perch ... but
I've got a pet theory I've never verified ... a theory that closes the loop
with your original report.  I am pretty sure that if you sealed that vent
line in the upper WG it would turn the air trapped in the upper WG chamber
into a parallel spring that would effectively stiffen the WG spring and
raise the max boost pressure.  Could that hose you have on the vent be
pinched by any chance?  I had a similar situation on a 5kT where the line
sealed the upper chamber and led to overboost shutdown triggers ... 

Steve B
San José, Kaleefohnia (USA)
> Turns out, the overboost cutout, if that is what is happening is still
> there, just not as prevalent as before.

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