| The needle lift sensor
consists of a coil which surrounds the shaft of an extended injection
needle of No. 1 injector. The ECM provides a DC supply to a coil which
produces a magnetic field. When the needle is moved under the influence of fuel pressure, the magnetic field is disturbed which induces an ac voltage in the coil. The induced voltage is registered in the ECM as a reference point for the start of the injection sequence. The ECM uses the input signals from the needle lift sensor, together with signal from the crankshaft sensor, to detect the actual start of injection. The ECM, using inputs from the other sensors, calculates then adjusts the injection timing of the fuel pump to achieve optimum fuelling of the engine. |
The engine coolant temperature sensor is a ’thermistor’ (a
temperature dependent resistor), i.e. the voltage output varies in
proportion to temperature. The sensor is located in the No. 3
cylinder head. The ECM constantly monitors the signal and uses the
information to correct the quantity of fuel injected and the
injection timing especially during cold starting. During starting,
output from the sensor determines how long the glow plugs are on.
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