Turbo boost questions about an 87 5k fwd 5spd.

Tyson Varosyan tigran at tigran.com
Wed Sep 1 16:42:33 EDT 2004

Hi Guys,

Anyway, bought my engine donor car last night. (Taking the turbo motor and
squeezing into my 4kq) Car seems to have "a little" overboost problem...
Seems that the waste gate is not working at all and boost just goes out of
control until what feels like a fuel cut. I have 4 main questions.

#1 Is the stock digital boost gauge in the car accurate or is it like many
cars, just goes up and down to make the new buyer feel good?
#2 Is the boost gauge driven by an actual boost pressure reading or is it
some electronic gizmo that calculates what it thinks the boost should be?
(My previous car, had a "boost" gauge that ran from the ECU. The ECU would
calculate based on the air intake sensor and the fuel delivery numbers of
what the boost should be. The gauge did measure "engine load" pretty well,
but it had nothing to do with the actual pressure in the manifold.)
#3 What is the stock boost limit on these cars? (i.e.. at what point is the
waste gate supposed to activate?)
#4 Is there an easy procedure to test the wastegate? (My other car had
internal wastegates and the actuators could be pressurised with a pump or
compressed air to make the actuator arms move. Given that this is a closed
in "box" I am not sure of how I can test it...)

I got some cheese ball Hayes manual with the car, but it's so worthless....
I'm looking for a Bentley online...

Thanks for the advice!

Tyson Varosyan
Technical Manager, Uptime Technical Solutions LLC.
tyson at up-times.com
206-715-TECH (8324)


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