overboosting (1987 5kcstq)

[Brian Devlin]

So....I can mess with one hose on my 86 5ktq and get more boost? And
at lower RPMs? Why spend all that money on springs, chips , turbos
and downpipes when I get put a calibrated leak into a hose? What key
piece on information am I missing here?
If you could recommend a book containing these pieces of information,
that'd be great. The Bentley isn't exactly a textbook.
-Brian

>On the way home from the QCUSA driver's school at Sears Point (my car
>was just parked there, I was taking pictures) my car developed a massive
>overboost problem. Perfectly drivable as long as I keep my foot out of
>it, but boost comes on much stronger and at lower RPMs than usual...at
>minimal throttle I hit 1.8 bar on the gauge and hit overboost (qlcc
>chip, Scott Mockry 1.8 bar spring...like a Charlie spring). I made it
>home fine, in fact didn't hit overboost once after realizing what was up
>and keeping my foot out of it.
>
>I stopped to take a peak at a gas station, but not much light. No
>obvious hose problems at the WG lower chamber so I am guessing it is a
>sticking WG (doubtful, this came on all of a sudden), or more likely, a
>torn WG diaphragm.
>
>Questions:
>
>1. Am i okay to keep driving the car (as in the 200 mile round trip to
>Sears Point tomorrow)? I assume so, if I keep my foot out of it like I
>did on the way home. Doesn't qlcc code go full rich above a certain
>boost level anyway (thinking lack of WOT switch, there's no way to get
>the throttle to that position). I have the version that will control
>boost without the help of the spring.
>
>2. Who has WG diaphragms in the US???? (I'll ask the Bennett brothers
>tomorrow as well since they're up at Sears Point.)
>
>BTW, an aside...my first attempt at shooting on-track with my new toy,
>er tool, an Olympus E-10 digital (which I hope to offer on-site prints
>with starting next season). I'll post the gallery url as soon as I have
>the shots up...I'm posting this prior to even downloading the memory
>cards so we'll see how I did.
>
>TIA!
>
>Mike Veglia
>Motor Sport Visions Photography
>http://www.motorsportvisions.com