Nissan PULSAR N13 Series / ASTRA LD Series. Instruction — part 21

Fuel and Engine Management

85

View of the 1.6 liter engine showing the engine management components.

Air cleaner removed for clarity.

series of tests on various components in the system
and records the results, If a fault is discovered, the
ECM warning lamp on the instrument cluster will
illuminate while the engine is running. When the self
diagnosis mode is activated, the ECM warning lamp
will flash codes indicating the area in which the fault
has occurred.

This function is very useful in locating system

faults, particularly intermittent problems. However,
the self diagnosis mode does not provide comprehen-
sive testing of the EFI system, and therefore should
always be used in conjunction with the other test
procedures described later in this section in order to
accurately locate system faults.

The high energy electronic ignition system con-

sists of a distributor and an ignition coil.

The distributor has two functions. The first is to

produce and distribute secondary high tension voltage
to the spark plugs.

The second function is to provide the control unit

with information on engine speed and crankshaft
position.

The ignition timing is constantly adjusted by the

control unit to suit varying engine and vehicle oper-
ating conditions.

In the fuel injection system, a metered amount of

fuel is sprayed into the air stream. The air/fuel

mixture then enters the combustion chamber via the
inlet valves.

On 1.6 liter engines, the fuel is injected by a single

injector, located above the throttle valve within the
throttle body assembly. The injector fires twice per
engine revolution under most operating conditions.

On 1.8 liter engines, four injectors are used. The

fuel is distributed to the injectors via the fuel rail. All
injectors fire simultaneously once per engine revolu-
tion under most operating conditions.

Under conditions of high load the control unit

may signal the injector(s) to fire more often. However,
if the engine speed exceeds 6 700 rpm the control unit
will cease firing the injectors until the engine speed is
below 6 200 rpm.

Fuel is supplied under pressure by an electric fuel

pump mounted in the fuel tank and the pressure is
regulated by a pressure regulator.

On 1.6 liter engines, the regulator consists of a

spring tensioned diaphragm which is mounted to the
side of the throttle body assembly. The fuel pressure is
regulated by the tension of the spring against the
diaphragm, opening and closing the fuel return port.

On 1.8 liter engines, the pressure regulator is

mounted adjacent to the fuel rail and consists of a
diaphragm with fuel pressure acting on one side and
spring tension and manifold vacuum acting on the

86

Fuel and Engine Management

other. The fuel pressure is maintained at a constant
pressure relevant to the manifold vacuum. A dispos-
able paper element fuel filter is mounted on the engine
bulkhead.

The amount of fuel injected is relevant to the time

the injector remains open. The basic time the injector
remains open is governed by the control unit which
uses information from the various sensors to give
optimum engine efficiency for given conditions.

The idle air control (IAC) valve controls the fast

idle speed during engine warm up and maintains the
basic idle speed at a set value by compensating for
loads such as air conditioning or the selection of Drive
on automatic transaxle models.

The throttle body assembly is mounted to the

inlet manifold and controls the amount of air entering
the engine by the action of the throttle valve.

Efficient operation of the EFI system depends on

accurate signals being received by the control unit and
controlled air flow beyond the throttle valve. There-
fore it is essential that all air, fuel and electrical
connections be clean and tight.

3. SERVICE PRECAUTIONS AND

PROCEDURES

Electronic ignition systems can produce danger-

ously high voltages in both the primary and secondary
circuits. For this reason, extreme care must be taken
when working on or near the ignition system.

Do not start the engine if the battery terminals are

not clean and tight.

Do not use the fast charge or boost settings on a

battery charger to start the engine.

Do not disconnect the battery terminals while the

engine is running.

Disconnect the battery terminals before charging

the battery.

Disconnect the negative battery terminal before

working on the engine management system.

Do not subject the control unit to temperatures

above 80 deg C.

Ensure that all wiring connectors are clean and

tight.

Disconnect the battery terminals and the control

unit wiring connectors before attempting any welding
operations.

Do not direct a steam cleaning or pressure

washing nozzle at engine management components
when cleaning the engine.

Ensure that the ignition is Off prior to disconnect-

ing the battery terminals, fusible links or the control
unit wiring connectors.

TO CONNECT ELECTRICAL TEST
EQUIPMENT

NOTE: Some types of tachometers, timing

lights and ignition system analysers are not
compatible with this engine management
system and may result in incorrect readings.
It is therefore recommended that the man-
ufacturer of the lest equipment be consulted
before proceeding to use the equipment.

If a test procedure requires the use of a

test lamp or voltmeter, ensure that only the
specified instrument is used to prevent mis-
leading diagnosis.

MULTIMETER

It is essential that in all tests where voltage or

resistance is to be measured, a digital display multi-
meter with a minimum 10 megohms impedance be
used.

The correct method of backprobing the wiring connec-

tors. The meter test probe should be modified with a

piece of thin wire as shown.

All meter readings are to be performed with the

component wiring connectors installed unless other-
wise instructed. This can be done by inserting the
meter test probes from the wiring harness side of the
connector or backprobing. If the test probes are not
thin, they should be modified by attaching a thin piece
of wire to the end, giving a fine point that will not
damage the connector. Ensure that the wire is making
good contact with the probe.

If sealing plugs or boots are removed from wiring

connectors to facilitate backprobing, ensure that they
are correctly installed at the conclusion of the test
procedure.

To identify wiring connector terminals refer to the

wiring circuit diagrams.

Test Lamp

To avoid damage to the electronic components

when testing, the use of an LED (light emitting diode)
test lamp is recommended.

Fuel and Engine Management

87

Fuel system wiring diagram for the 1.6 liter engine.

88

Fuel and Engine Management

Fuel system wiring diagram for the 1.8 liter engine.

BR K