Fuelling system

Using the signal from the knock sensor in conjunction with the CKP and CMP signals enables the ECM to identify which cylinder is producing the knock and hence retard the ignition timing of that cylinder only. The ignition timing of the cylinder producing the knock is retarded until the knock disappears. The ECM then advances the ignition timing to find the optimum advance angle for that cylinder. The ECM is able to perform a similar function for each of the 8 cylinders simultaneously. It is therefore possible for all 8 cylinders to have different advance angles at any one time.

FUELLING SYSTEM

Engine fuelling is by a fully sequential, electronic fuel injection system, controlled by the ECM. The ECM determines the timing and quantity of fuel to be injected based on information received from the following sensors.

• Crankshaft position (CKP) sensor - engine speed and crankshaft position
• Camshaft position (CMP) sensor - camshaft position
• Mass air flow (MAF) sensor - quantity of air entering the engine
• Throttle position (TP) sensor - position of throttle and rate of change of throttle
• Engine coolant temperature (ECT) sensor - engine coolant temperature
• Fuel temperature sensor - temperature of fuel rail
• Heated oxygen sensor (HO2S) - oxygen content of exhaust

Crankshaft position (CKP) sensor

The CKP sensor signal is used as the basis for fuel injection timing. It informs the GEMS that the engine is turning, the speed the engine is turning and position of the engine in the cycle.

The sensor uses the principle of magnetic induction to generate the signal. A reluctor ring, attached to the engine flywheel, has a series of teeth spaced at 10° intervals, with one tooth missing at 20° after TDC. The reluctor ring rotates with the engine, in close proximity to the CKP sensor. As each tooth of the reluctor ring passes the sensor, it disturbs the magnetic field of the sensor and a voltage is induced in the sensor coil. The ECM calculates engine speed by counting pulses per second from the CKP sensor. Engine position is calculated by counting pulses after the missing pulse.