Component Description

Engine Management System:

Mass Air Flow Sensor
The Mass Air Flow Sensor (MAFS) (4), measures the quantity of air drawn into the engine and reports to the ECM.

Intake Air Temperature Sensor
The Intake Air Temperature Sensor (IATS) (5), measures the temperature of the air in the induction tract and reports to the ECM.

Idle Speed Control Valve
The Idle Speed Control Valve (ISCV) (6), responding to ECM output signals and in conjunction with ignition timing control, governs engine idle speed.

Engine Coolant Temperature Sensor
The Engine Coolant Temperature Sensor (ECTS) (7), monitors the engine operating temperature and reports to the ECM.

Fuel Pump
The fuel pump (8), situated in the fuel tank, supplies fuel to the fuel rail (9); the fuel pressure regulator (10), in the fuel rail, controls the fuel pressure at the fuel injector (FI) (11), which injects fuel into the area behind the inlet valve, when commanded by the ECM.

Fuel Volume
The volume of fuel injected is governed by the length of time the injector is open; this time/quantity, required to achieve the correct mixture, is controlled by the ECM.

Ignition system
Ignition is by spark plugs with attached individual coils (12). Timing of ignition is varied according to speed and load.

Heated Oxygen Sensors, Exhaust Gas Emission
The combustion gases, after passing through the exhaust manifold, enter the catalytic convertor (13), where the quality of the exhaust gas emission is modified. The quality of the exhaust gas emission is constantly checked by the Heated Oxygen Sensors (HO25) (14), which are situated both upstream and downstream of the catalysts. By comparing the signal outputs of pre and post catalyst sensors the ECM can make corrections to the fuel and ignition settings as necessary. The sensors contain integral Heaters which accelerate the warming-up of the sensors to enable a rapid correction of initial settings which may be causing the emission of low quality exhaust gases.

Throttle Position Sensor
Throttle position is detected by the Throttle Position Sensor (TPS) (15), which reports to the ECM.

Exhaust Gas Recirculation Valve
The Exhaust Gas Recirculation (EGR) Valve (16), when activated by the ECM, allows exhaust gas to enter the intake air stream to dilute the oxygen content of the combustible fuel/air mixture, so lowering combustion temperatures and consequently Nitrous Oxide emissions. The temperature of the introduced gases is monitored by the adjacent EGR function sensor (17).

Knock Sensor
If combustion knock is detected by the Knock Sensor (KS) (18), ignition timing, which is normally at optimum advance, may be retarded on specific cylinders.

Crankshaft Position Sensor
Engine speed is measured by the Crankshaft Position Sensor (CKPS) (19), which also monitors differences in crankshaft acceleration between cylinders, to detect specific cylinder low performance (misfire).

Engine Position Sensor
Engine position is measured by the Engine Position Sensor (CM CMP) (20). This measurement is used by the ECM to determine the commencement of injection.

Secondary Air Injection
The Secondary Air Injection (AIR) Pump (21), on command from the ECM, via a relay, provides additional air to reduce the level of Carbon Monoxide (CO) and Hydrocarbons (HC), in the exhaust gases. The additional air accelerates the rise in exhaust temperature to rapidly reach the catalyst operating temperature level. When the relay energizes the pump in the AIR system it also energizes the solenoid controlling the integral stop valve, opening the air line, through the mechanical check valve (22), to the exhaust manifold.

Fuel Tank
The fuel tank (23), has a fuel capacity of 90% of the tank volume. The air volume above the fuel is vented to atmosphere through an activated charcoal canister (24), which absorbs the fuel vapor. As fuel is withdrawn from the tank, air is drawn in through the canister and as the fuel laden air in the tank expands, pressure is relieved through the canister which retains the suspended fuel.

Canister Purge Valve
The canister purge valve (25), responds to an ECM signal and opens the canister line to inlet manifold vacuum; air then flows through the activated charcoal canister, carrying vapor into the inlet manifold.

Fuel Level
Fuel level is measured by the fuel level sensor (26).

Park/neutral
The park/neutral switch (27), Security and Locking Control Module (SLCM) (28) and ignition on (29), signals are conveyed to the ECM input. Signals are conveyed to the instrument pack (road speed) (30), trip computer (31), diagnostic MIL lamp (32), Data Link Connector (DLC) (33), and Transmission Control Module (TCM) (Torque Control) (34), from the ECM.

Inertia Switch
The inertia switch (35), ensures that electrical power is cut off when the vehicle is subjected to a violent deceleration.