Porsche 1972 911 Workshop Manual page 167

C o n t r o l P r e s s u r e R e g u l a t o r
(Throttle Valve Position)
The control pressure regulator for throttle valve
position is basically similar to the regulator for
the throttle valve housing.
A cam plate is attached to the throttle valve
shaft and rides along with it, compressing the
regulator spring to a greater or lesser degree.
This changes the control pressure along with
changed throttle valve position, adjusting the
A u x i l i a r y A i r D e v i c e
When decelerating from high rprn with throttle
closed, considerable vacuum builds up in the
intake manifold. The vacuum is channeled to
an auxiliary air device. As
additional air bypasses the throttle creating a
combustible mixture.
I d l e A d j u s t m e n t
The adjusting method is same as that for carbure-
tors. The idle air mass passes through the air flow
sensor where it is measured. The closed throttle
is bypassed through a bypass bore.
The cross-section of this bore can be changed
with the aid of an adjustment screw. A change
in cross-section changes the engine speed with-
out affecting the composition of the fuel/air
mixture.
The fuel/air mixture can b e adjusted within
certain limits by means of a mixture adjusting
screw to attain the required effect.
the device opens,
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D e s c r i p t i o n