| Throttle
Switch |
| The
throttle switch, in a pressure type system, is
used to bridge the gap or time delay between the
time intake pressure signals the ECU for an increase
in fuel versus the immediate call for fuel when
the throttle plate is opened. The throttle switch
performs the same function as the accelerator
pump does on a vehicle equipped with a conventional
carburetor.
The
throttle switch is connected directly to the
throttle plate. It consists of two contact arms,
which slide or sweep across a graduated zigzag
contact path. This zigzag pattern allows the
ECU to receive signals as the contact arm sweeps
up that the throttle is being depressed and
therefore enrich the fuel. One contact path
is used for acceleration while the other contact
path is contains a full load and an idle contact.
|
| Pressure
Sensor |
| The
pressure sensor is the most critical sensor in
the D Jetronic system. The pressure sensor is
housed in a metal housing and contains two diaphragm
cells, which displace an armature that is inside
a coil. When the armature is moved inside the
coil, the inductance of the coil changes Therefore,
the pressure sensor converts a pneumatic signal
into an electrical signal which the ECU can measure
and determine the correct duration of the injector
pulses.
One
chamber of the pressure sensor is at atmospheric
pressure while the other is at intake manifold
pressure since a vacuum line is connected from
the intake manifold to the pressure sensor.
The difference between these two pressures will
cause the armature to move within the coil changing
the induction of the coil. The resulting electrical
value that the ECU receives will determine the
load of the engine and consequently the amount
of fuel to be injected. Pretty trick for the
late sixties.
|
|
| Series
Resistors |
| Some
D Jetronic systems use a set of resistors to drop
the voltage to the injectors. We have rarely seen
these fail. |
|
