General information and precautions

General information From the 1990 model year, an Electronic Fuel Injection (EFI) system controlled by the Electronic Engine Control IV (EEC IV) system, and incorporating an Electronic Distributorless Ignition system (E-DIS 4) is used on all 1.6 litre fuel injection models. The system is designed to meet the requirements of the European 15.04 exhaust emission control laws.

Those components more easily related to the ignition system are described in Chapter 5, Part B. Those relating to the fuel system are described in this Section.

The engine management and fuel systems are best described by dividing them into two separate sub-systems the air inlet system, and the fuel system.

Air inlet system
The volume of air drawn into the system depends on air pressure and density, throttle valve position, engine speed and the cleanliness of the air cleaner element.

The EEC IV module evaluates these factors through the Air Charge Temperature (ACT) sensor, Manifold Absolute Pressure (MAP) sensor and Throttle Position Sensor (TPS), and controls the engine idle speed via the Idle Speed Control Valve (ISCV).

The air cleaner is similar to that used on earlier fuel injection models. A flexible hose connected to the valve cover acts as a cylinder head and crankcase breather. A further connection leads to the idle speed control valve. The valve is controlled by the EEC IV module, and operates by varying the size and opening duration of an auxiliary air passage, which by-passes the throttle valve.

A throttle housing bolted to the upper section of the inlet manifold houses the throttle valve and TPS. The TPS measures throttle opening.

The MAP sensor, mounted on the engine bulkhead and connected to the inlet manifold by a vacuum pipe and electrically to the EEC IV module, measures the vacuum in the inlet manifold. If the MAP sensor fails in service, the EEC IV module uses the TPS to provide one of three values:
a) Idle
b) Part load
c) Full load
Inlet air temperature is measured by an electrically resistive element in the air charge temperature sensor (ACT) screwed into the upper half of the inlet manifold. This supplies information to the EEC IV module.

Fuel system
The fuel pump and fuel level sender unit are contained in an integral unit in the fuel tank.

The fuel pump is electric, and its electrical supply is provided via a relay controlled by the EEC IV module. When the ignition is switched on, the fuel pump is given a lead-in time of approximately one second in order to build up pressure in the system. The pump also incorporates a non-return valve which prevents system pressure dropping after the ignition is switched off, to improve the warm start characteristics.

An inertia switch (located under the spare wheel in the luggage compartment), installed between the fuel pump relay and the fuel pump will break the supply to the pump in the event of sudden impact, thus switching off the pump. If the switch has been activated, the reset button will be in the raised position.

A fuel rail is bolted to the lower section of the inlet manifold. The fuel rail acts as a fuel reservoir for the four fuel injectors, and locates the injectors in the inlet manifold.

A fuel filter is installed between the fuel pump and the fuel rail.

A fuel pressure regulator, mounted on the return end of the fuel rail and connected by a pipe to the inlet manifold to sense manifold pressure, controls fuel pressure in the fuel rail.

Excess fuel is returned to the fuel tank.

The fuel injectors are electro-magnetically operated, and the volume of fuel injected is regulated by varying the electrical pulse duration which is computed by the EEC IV module.

A “limited operation strategy” (LOS) means that the vehicle is still driveable (albeit at reduced power and efficiency) in the event of a failure in the EEC IV module or its sensors.

Note: Following disconnection of the battery, all Keep Alive Memory (KAM) values will be erased from the EEC IV system module memory, which may result in erratic idle, engine surge, hesitation and a general deterioration of driving characteristics.

Warning: Many of the procedures in this Chapter entail the removal of fuel pipes and connections which may result in some fuel spillage. Before carrying out any operation on the fuel system refer to the precautions given in Safety First! at the beginning of this manual and follow them implicitly.

Petrol is a highly dangerous and volatile liquid and the precautions necessary when handling it cannot be overstressed Refer to the precautions given in Part B of this Chapter for models with mechanical fuel injection.

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