Engine management system

ENGINE MANAGEMENT SYSTEM

The Engine Control Module (ECM) monitors the conditions required for optimum combustion of fuel in the cylinder through sensors located at strategic points around the engine. As a result of these sensor inputs, the engine control module can adjust the fuel quantity and timing of the fuel being delivered to the cylinders.

The main features are as follows:

• A single ECM controls the fuel injection system and the ignition system. The ECM incorporates short circuit protection and can store intermittent faults on certain inputs. TestBook can interrogate the ECM for these stored faults.
• The ECM is electronically immobilised which prevents the engine from being started unless it receives a coded signal from the anti-theft control unit.
• In conjunction with the throttle position sensor the ECM uses the speed/density method of air flow measurement to calculate fuel elivery. This method measures the inlet air temperature and inlet manifold pressure and assumes that the engine is a calibrated vacuum pump, with its characteristics stored in the ECM, it can then determine the correct amount of fuel to be injected.
• A separate diagnostic connector allows engine tuning or fault diagnosis to be carried out using TestBook without disconnecting the ECM harness multiplug.
• The ECM harness multiplug incorporates specially plated pins to minimise oxidation and give improved reliability.
• The ECM controls the operation of the radiator and air conditioning cooling fans, based on signals received from the engine coolant temperature sensor.
• If certain system inputs fail, the ECM implements a back-up facility to enable the system to continue functioning, although at a reduced level of performance.

’K16 with VVC’ ECM - additional features

The ECM also controls the valve period, by driving the variable valve control (VVC) mechanism, to produce the optimum engine torque characteristic.

• The ECM measures the cam period via the cam sensor, and controls the VVC mechanism via two solenoids: one which increases the period and one which reduces the period.
• The ECM used on the VVC engine implements tune select which means that each ECM may contain engine calibrations for one or more vehicles. In order to prevent an ECM being fitted to a vehicle with the wrong calibration selected, when first supplied, the ECM has no calibration selected so the engine will not run. When fitted to a vehicle, the ECM calibration for that vehicle must be selected using diagnostics equipment in addition to programming the ECM security code.

IGNITION SYSTEM

The ECM determines the optimum ignition timing based on the signals from the following sensors:

1. Crankshaft position sensor - Engine speed and crankshaft position
2. Manifold absolute pressure sensor - Engine load
3. Engine coolant temperature sensor - Engine temperature
4. Manifold absolute pressure sensor - Throttle pedal released

The engine management system uses no centrifugal or vacuum advance. Timing is controlled by the ECM which is energised by the main relay, located within the relay module.

’K16’ models

Spark distribution is achieved by means of a rotor arm and distributor mounted at the No.4 cylinder end of the inlet camshaft.

’K16 with VVC’

The VVC engine employs a direct ignition system which consists of two twin-ignition coils driven directly from the ECM. Each twin-ignition coil supplies two cylinders.