Needle lift sensor (Engine management system - EDC)

Needle lift sensor

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.

FUEL INJECTION TIMING COMPENSATION

Engine coolant temperature sensor

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.