engine NISSAN PULSAR 1987 Manual PDF

Fuel and Engine Management
(4) MAP sensor faulty or supply hose discon-
nected or blocked: Check the vacuum supply hose.
Check the operation of the MAP sensor.

EXCESSIVE FUEL CONSUMPTION
(1) Blocked air cleaner element: Check the ele-
ment and clean or renew as necessary.
(2) Incorrect fuel pressure: Check the fuel pump
and fuel pressure regulator. (3) Faulty coolant temperature sensor: Check
the connections and operation.
(4) Leaks in the fuel supply system: Check the
connections and components for leakage. (5) Leaking fuel injector(s): Clean or renew the
faulty injector(s). (6) Engine operating temperature too low:
Check the thermostat and electric cooling fan as
described in the Cooling an d Heating Systems section.
2. DESCRIPTION
The engine management system on the range of
vehicles covered by this manual controls the opera-
tion of the ignition system and the fuel system.

The central component of the engine management
system is the electronic control unit (ECU). The con-
trol unit is a micro-computer which controls the igni-
tion timing and the amount of fuel injected according
to signals received from various sensors. As changes
are detected in engine load and speed, coolant tem-
perature, barometric pressure, air temperature (1.8
liter engine), throttle position and vehicle speed, the
control unit alters the ignition timing and the fuel
injection amount to achieve optimum engine effi-
ciency.

The control unit incorporates a self diagnosis
mode which stores and displays codes relating to
certain system malfunctions. Whenever power is sup-
plied to the control unit, the control unit performs a


View of the 1.8 liter engine showing the engine management components.
Ensure that all fuel connections are securely tightened.

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 simultaneous ly 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 pressu re 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 pressu re 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 receiv ed 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 ba ttery 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 measur ed, 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 bac kprobing, 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

Fuel and Engine Management 89
The procedure for fabricating an LED test lamp is
fully described in the El ectrical System section.

If a conventional test lamp with a filament type
bulb is to be used, ensure that the current draw of the
test lamp does not exceed 0.3 amp to avoid damage to
the electronic components.

To check the current draw connect an accurate
ammeter, such as the multimeter described previ-
ously, in series with the test lamp and a battery.

If the ammeter reads less than 0.3 amp the test
lamp is suitable.

Tachometer
(1) Disconnect the resistor from the tachometer
pick-up wiring connector which is located on the
ignition coil wiring harness, and connect the positive
lead of an accurate tachometer to the brown wire
terminal in the wiring connector. (2) Connect the negative lead to a good earthing
point.

View showing the location of the tachometer pickup
wiring connector with the resistor installed.
Timing Light
(1) Connect the timing light to the engine fol-
lowing the instrument manufacturers instructions.

NOTE: Do not connect or disconnect the
timing light with the engine running as
voltage surges could damage the alternator
or control unit. Do not allow the high
tension leads to open circuit with the engine
running as damage to the engine manage-
ment system could result.

(2) Do not connect the timing light positive lead
to the alternator output terminal. Where possible,
connect the power leads of the timing light to an
external power source to prevent possible transient
voltages damaging the alternator or control unit.

4. SYSTEM DIAGNOSIS AND ADJUSTMENTS
NOTE: Due to the use of complex electronic
components in the engine management sys-

tem, the diagnosis and testing procedures
described in this section should not be
carried out by persons lacking an under-
standing of electronics and the precautions
associated with the servicing of electronic
components. It is rec ommended that should
a fault arise in the system, the vehicle be
referred to an authorized workshop.

The control unit can be damaged by
component faults not indicated by the self
diagnosis codes and the renewal of the
control unit without lo cating the cause of
the failure will result in the failure of the
replacement unit. It is for this reason that
the practice of substituting components to
isolate faults is not recommended.

Prior to performing any of the follow-
ing operations, refer to the Service Pre-
cautions and Procedures heading.

PRELIMINARY CHECKS
Prior to performing the Self Diagnosis Test Pro-
cedures, perform the following preliminary checks and
rectify any problems as necessary.

(1) Check for an adequate supply of fuel in the
fuel tank. (2) Check the wiring connectors and earth points
of all engine management components for clean,
secure connections. To prevent damage to the control
unit, disconnect the negative battery terminal before
disconnecting any engine ma nagement wiring connec-
tors. (3) Check the condition of the battery. Refer to
the Electrical System sectio n for checking procedures.
Rectify any faults as necessary. (4) Check the air cleaner element for restriction.
(5) Check for air leaks at the throttle body, inlet
manifold and all related hoses. (6) Check the fuel pump pr essure as described
later in this section. (7) Ensure that the engine is in a satisfactory
mechanical condition and is in tune. Refer to the
Engine and Engine Tune-up sections as necessary.
SELF DIAGNOSIS

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 engine management system, and
therefore should always be used in conjunction with
the other test procedures described later, in order to
accurately locate system faults.

To Interpret Self Diagnosis Codes
Once the self diagnosis mode is activated, various
fault codes will be displayed as a series of flashes by
the ECM warning lamp on the instrument cluster.

90 Fuel and Engine Management
To identify the code number, count the number of
times the ECM warning lamp flashes. Each fault code
comprises two groups of flashes separated by a 1.2
second pause. The first group represents tens and the
second group represents single units. For example 1
flash followed by a 1.2 second pause followed by 4
flashes would be code number 14. Similarly 4 flashes
followed by a 1.2 second pause followed by 2 flashes
would be code number 42.

The code will be displayed three times. If more
than one fault code is present, the self diagnosis
system will indicate each one in numerical order, with
a 3.2 second pause between each code, and then
repeat the sequence.

The fault codes can be identified as follows:
CODE NUMBER FAULT AREA
12 Satisfactory operation
13 Oxygen sensor open circuit
14 Coolant temperature sensor circuit (voltage low)
15 Coolant temperature sensor circuit (voltage high)
21 Throttle position sensor circuit (voltage high)
22Throttle position sensor circuit (voltage low)
23MAT sensor circuit (voltage' high) 1.8 liter engine
only
24 Vehicle speed sensor circuit
25 MAT sensor circuit

(voltage low) 1.8 liter engine
only
33 MAP sensor circuit

(voltage high)
34MAP sensor circuit (voltage low)
42 Electronic spark timing circuit
44
Oxygen sensor circuit

(lean exhaust)
45Oxygen sensor circuit (rich exhaust)
51 Mem-Cal
55 Control unit input circuits
Test Procedure
(1) Perform the following checks:

(a) Ensure that the battery voltage is above 11
volts. (b) Ensure that the throttle valve is fully closed.
(c) Place the transaxle in neutral.
(d) Ensure that the air conditioner, fan, tights
and all other accessories are switched off.
(2) Turn the ignition On and confirm that the
ECM warning lamp on the instrument cluster is
illuminated but not flashing.

If code 55 is displayed, refer to the Control Unit
heading, perform the circuit test procedure and rectify
the cause of the code before proceeding.

If the ECM warning lamp flashes codes other than
code 55, check the wiring harness between the diag-
nostic link connector terminal B and the control unit
wiring connector terminal A9 for shorts. Repair or
renew the wiring harness as necessary.

If no fault can be found, renew the control unit.
If the ECM warning lamp does not illuminate,
proceed as follows:

(a) Check the METER fuse located in the fuse
panel adjacent to the steering column and the fusible
links located in the fusible link connecting block at the
rear of the battery. Renew the fuse or fusible links as
necessary. (b) Check the wiring harness to the instrument
cluster. Repair or renew the harness. (c) Check the Check Engine lamp bulb. Renew if
necessary. (d) Check the EGI relay. Renew as necessary.
(3) Connect a jumper lead across terminals A
and B on the diagnostic link connector located under
the front passengers seat above the control unit.
(4) Note the codes indicated by the flashing
ECM warning lamp.
If code 12 is displayed, the system is operating
correctly.

If codes other than code 12 are displayed, refer to
the component or circuit test procedure under the
appropriate heading as indicated by the code number.

If more than one code is being displayed, test each
indicated fault working in the order of display of the
code numbers.

(5) After completing the self diagnosis test pro-
cedure, remove the jumper lead from the diagnostic
link connector. (6) After repairing or renewing the necessary

View showing the location of the diagnostic link
connector. Passengers seat removed for clarity.
Inset shows the diagnostic link connector terminal identification.

Fuel and Engine Management 91
components, erase the self diagnosis memory as
described under the following heading.

(7) Repeat the self diagnosis test procedure and
ensure that code 12 is displayed.

To Erase Memory
(1) With the ignition Off, remove the fusible link
that is positioned third from the front of the fusible
link connecting block located at the rear of the
battery. (2) Install the fusible link after 10 seconds.

View showing the location of the fusible links.
TO CHECK AND ADJUST IGNITION TIMING
(1) Connect a timing light to the engine as
previously described under the Service Precautions
and Procedures heading.
(2) Start the engine and allow it to reach normal
operating temperature. (3) Connect a jumper lead between terminals A
and B on the diagnostic link connector. (4) With the engine idling at the specified speed,
check the ignition timing with the timing light.
The timing mark on the crankshaft pulley should
be aligned with the pointer on the inner liming belt
cover.

(5) If necessary, loosen the distributor body
retaining nuts and turn the distributor until the timing
marks are aligned. (6) Tighten the distributor body retaining nuts
and check that the timing is correct. (7) Remove the jumper lead from the diagnostic
link connector and disconnect the timing light from
the engine.
TO ADJUST BASE IDLE SPEED

NOTE: The idle speed is controlled by the
idle air control (IAC) valve and is not

adjustable. The throttle stop screw controls
the base idle speed a nd is factory set. The
following base idle speed adjustment should
only be performed if the throttle body has
been renewed, or if comprehensive testing of
related components indicates that adjust-
ment is required.

(1) Before adjusting the base idle speed perform
the following tests;

(a) Check the spark plug gaps, the high tension
leads and the ignition timin g as described previously
in the Engine Tune-up section.
(b) Check the air inlet syst em for leaks between
the throttle body and inlet manifold and the inlet
manifold and cylinder head.
NOTE; Any vacuum leaks will make the
engine idle faster than it should.

(c) Check that all wiring connectors and vacuum
hoses are securely connected. (d) Ensure that the transaxle is in Park or
Neutral. (e) Ensure that the air cleaner element is service-
able.

(2) On 1.6 liter engines, remove the air cleaner
assembly, disconnect the vacuum hose from the
throttle body and seal the vacuum hose fitting.
(3) Ensure that the throttle valve moves freely
and returns to the fully closed position when slowly
released. (4) Connect an accurate tachometer to the en-
gine as previously descri bed under the Service Pre-
cautions and Procedures heading.
(5) Start the engine and allow the engine to
warm up and the idle rpm to stabilize. Check that all
electrical accessories and the air conditioning, if
equipped, are turned off. (6) With the engine idling in Park or Neutral,
slowly disconnect the brake servo unit vacuum supply
hose from the inlet manifold. Allow the engine to run
for one minute.
Location of the base idle adjusting screw. 1.8 liter
engine.

92 Fuel and Engine Management

Installed view of the throttle body assembly showing
the location of the base idle adjusting screw. 1.6 liter
engine.
(7) Disconnect the IAC valve wiring connector
and slowly connect the vacuum supply hose to the
inlet manifold. Allow five seconds to elapse and note
the engine speed.
(8) If the engine speed is not to Specifications,
remove the plug from the throttle body housing on 1.6
liter engines, or the cap from the base idle adjusting
screw on 1.8 liter engines, and adjust the idle screw
until the engine speed is 625 rpm. (9) Stop the engine and connect the IAC valve
wiring connector. (10) On 1.8 liter engines, install a new cap to
the
base idle adjusting screw.
On 1.6 liter engines, seal the throttle stop screw
with silicone sealant and install the air cleaner assem-
bly.

(11) Erase the memory codes as previously de-
scribed.
(12) Start the engine and increase the speed to
3 000 rpm for 10 seconds to allow the idle air control
valve to reset.
5. FUEL SUPPLY COMPONENTS

Special Equipment Required:
To Check Fuel Pressure — 0-500 kPa pressure
gauge

NOTE: Before proceeding with any of the
operations in this section, refer to the Ser-
vice Precautions and Procedures heading.

TO DEPRESSURISE FUEL SYSTEM
(1) Lift the front edge of the rear seat cushion on
each side, slide the cushion forward and remove it
from the vehicle. (2) Disconnect the fuel pump wiring harness
connector.
When depressurizing the fuel system, remove the rear
seat cushion and disconnect the fuel pump wiring
connector.
(3) Start and run the engine until it stalls.
Operate the starter motor for 10 seconds to ensure
that the pressure has dissipated.
(4) Connect the fuel pump wiring connector and
install the rear seat cushion.
NOTE: Failure to depressurize the fuel sys-
tem when instructed may result in a fuel
spray and possible fire.

TO TEST FOR EXTERNAL LEAKS
(1) Connect a jumper lead between terminals G
and H on the diagnostic link connector.
(2) Switch the ignition On.
(3) Check for leaks at all hose connections and
joints between the fuel pump and the engine. (4) Switch the ignition Off and remove the
jumper lead from the diagnostic link connector.
(5) If renewal of a component is necessary,
depressurize the fuel system as previously described. (6) Use only hoses and clamps as specified by
the manufacturer.
TO CHECK FUEL PRESSURE

(1) Depressurize the fuel system as previously
described. (2) On 1.6 liter engines, remove the air cleaner
as described in this section under the Air Cleaner
Assembly heading. (3) On 1.8 liter engines, release the hose clamp
securing the fuel supply hos e to the fuel rail and
disconnect the hose. On 1.6 liter engines, release the hose clamp
securing the fuel supply hose to the rear throttle body
hose fitting and disconnect the hose.

(4) Using a suitable gauge, tee piece, short piece
of fuel hose and clamps, install the pressure
gauge
between the fuel supply ho se and the fuel rail on 1.8

Fuel and Engine Management 93
liter engines, or the throttle body hose fitting on 1.6
liter engines.

(5) Tighten all connectors securely. Check for
external leaks as previously described. (6) Start the engine and note the pressure while
the engine is idling.
(7) Switch the engine Off and check that the
residual pressure does not decrease.
If the fuel pressure is within Specifications and
does not decrease, the fuel system is in a serviceable
condition. Depressurize the fuel system and discon-
nect the pressure gauge.

If the fuel pressure is a bove Specifications proceed
to operation (9).

If the fuel pressure is below Specifications proceed
to the following operation.

If the fuel pressure decreases, an internal leak is
indicated. Proceed to the following heading and carry
out the test procedure.


Testing the fuel system pressure using a pressure
gauge. 1.8 liter engine.
NOTE: There may be a small initial de-
crease in pressure when the engine is
switched Off This is acceptable and does not
indicate a fault in the system.

(8) If the fuel pressure is below Specifications
proceed as follows:

(a) Check the fuel lines for blockages and kinks
or a blocked fuel filter or fuel pump pickup strainer. (b) If no fault can be found in the previous
checks, on 1.8 liter engines clamp the fuel return hose
at the fuel rail. On 1.6 liter engines, clamp the hose that is
connected to the front throttle body hose fitting.

(c) Connect a jumper lead between terminals G
and H on the diagnostic link connector and switch the
ignition On.

NOTE: Do not operate the fuel pump for
longer than is necessary to obtain a pressure
reading.

If the fuel pressure is less than 270 kPa on 1.8 liter
engines or 90 kPa on 1.6 liter engines, renew the fuel
pump.

If the fuel pressure is more than previously
specified, renew the pressure regulator assembly on
1.8 liter engines or the pressure regulator diaphragm
on 1.6 liter engines.

(9) If the fuel pressure in operation (6) is above
Specifications, proceed as follows:

(a) On 1.8 liter engines, disconnect the fuel
return hose from the pressure regulator outlet.

On 1.6 liter engines, disc onnect the fuel return
hose from the front throttle body hose fitting.

(b) Connect a suitable length of fuel hose to the
pressure regulator or the front throttle body hose
filling and place the opposite end of the hose into a
petroleum resistant container. (c) Connect a jumper lead between terminals G
and H on the diagnostic link connector and switch the
ignition On. If the fuel pressure is 230-270 kPa on 1.8 liter
engines or 62-90 kPa on 1.6 liter engines, locate and
remove the restriction in the fuel return hose or pipe.

If the fuel pressure is more than previously
specified, renew the pressure regulator assembly on
1.8 liter engines or the pressure regulator diaphragm
on 1.6 liter engines.

TO TEST FOR INTERNAL FUEL LEAKAGE
Check the residual fuel pressure as previously
described.

If the pressure has decreased it is an indication of
an internal leak. With the pressure gauge still at-
tached, proceed as follows:

(1) Switch the ignition On to pressurize the fuel
system.
(2) As the pressure begins to decrease clamp the
fuel supply hose shut. If the pressure remains steady
the fuel pump may be consid ered faulty and should be
renewed as described later in this section. (3) If the pressure continues to decrease switch
the ignition On after it has been Off at least 10
seconds. As the pressure begi ns to decrease clamp the
fuel return hose shut. If the pressure remain steady on 1.8 liter engines,
renew the pressure regulator. If the pressure continues
to decrease, leaking inject ors are indicated. Remove
the injectors as described later in this section to locate
the leaking injectors.

If the pressure remains stea dy on 1.6 liter engines,
renew the pressure regulator diaphragm as described
later in this section. If the pressure continues to
decrease remove the injector and renew the O ring
seals as described later in this section. If this fails to
rectify the fault remove the injector and clean or
renew the injector as necessary.