1998 NISSAN PICK-UP sensor

System Chart
Camshaft position sensorc
ECM
(ECCS
control
module)
Mass air flow sensorc
Engine coolant temperature sensorc
Heated oxygen sensor*c
Ignition switchc
Throttle position sensorc
Neutral position switchc
Vehicle speed sensorc
Air conditioner switchc
Battery voltagec
Power steering oil pressure switchc
Intake air temperature sensorc
*: LHD models
Fuel injection &
mixture ratio controlcInjectors
Distributor ignition systemcPower transistor
Idle air control systemcIACV-AAC valve
IACV-FICD solenoid valve
Swirl control valve controlcSwirl control valve control
solenoid valve
EVAP canister controlcEVAP canister purge control
solenoid valve
Fuel pump controlcFuel pump relay
Heated oxygen sensor moni-
tor & on board diagnostic
systemcMalfunction indicator lamp
(On the instrument panel)
Acceleration cut controlcAir conditioner relay
Heated oxygen sensor
heater control*cHeated oxygen sensor
heater
ENGINE AND EMISSION CONTROL OVERALL SYSTEMKA
EC-13

Multiport Fuel Injection (MFI) System
INPUT/OUTPUT SIGNAL LINE
Camshaft position sensorcEngine speed and piston position
ECM
(ECCS
control
module)
cInjector
Mass air flow sensorcAmount of intake air
Engine coolant temperature sensor
cEngine coolant temperature
Heated oxygen sensor*
cDensity of oxygen in exhaust gas
Throttle position sensor
cThrottle position
Throttle valve idle position
Neutral position switch
cGear position
Vehicle speed sensor
cVehicle speed
Ignition switch
cStart signal
Battery
cBattery voltage
*: LHD models
BASIC MULTIPORT FUEL INJECTION
SYSTEM
The amount of fuel injected from the fuel injector is
determined by the ECM. The ECM controls the
length of time the valve remains open (injection
pulse duration). The amount of fuel injected is a
program value in the ECM memory. The program
value is preset by engine operating conditions.
These conditions are determined by input signals
(for engine speed and intake air) from both the
camshaft position sensor and the mass air flow
sensor.
VARIOUS FUEL INJECTION
INCREASE/DECREASE COMPENSATION
The amount of fuel injected is compensated for to
improve engine performance. This will be made
under various operating conditions as listed below.

lDuring warm-up
lWhen starting the engine
lDuring acceleration
lHot-engine operation
lHigh-load, high-speed operation
lWhen swirl control valve operates

lDuring deceleration
lDuring high-engine speed operation
lExtremely high-engine coolant temperature
ENGINE AND EMISSION BASIC CONTROL SYSTEM DESCRIPTIONKA
EC-14

MIXTURE RATIO FEEDBACK CONTROL
The mixture ratio feedback system provides the best air-fuel
mixture ratio for driveability and emission control. The three way
catalyst can then better reduce CO, HC and NOx emissions. This
system uses a heated oxygen sensor in the exhaust manifold to
monitor if the engine is rich or lean. The ECM adjusts the injec-
tion pulse width according to the sensor voltage signal. For more
information about heated oxygen sensor, refer to page EC-123.
This maintains the mixture ratio within the range of stoichiomet-
ric (ideal air-fuel mixture).
This stage is referred to as the closed loop control condition.
OPEN LOOP CONTROL
The open loop system condition refers to when the ECM detects
any of the following conditions. Feedback control stops in order
to maintain stabilized fuel combustion.
lDeceleration and acceleration
lHigh-load, high-speed operation
lEngine idling
lMalfunction of heated oxygen sensor or its circuit
lInsufficient activation of heated oxygen sensor at low engine
coolant temperature
lHigh-engine coolant temperature
lDuring warm-up
lWhen starting the engine
MIXTURE RATIO SELF-LEARNING CONTROL
The mixture ratio feedback control system monitors the mixture
ratio signal transmitted from the heated oxygen sensor. This
feedback signal is then sent to the ECM. The ECM controls the
basic mixture ratio as close to the theoretical mixture ratio as
possible. However, the basic mixture ratio is not necessarily con-
trolled as originally designed. Both Manufacturing differences
(i.e. mass air flow sensor hot wire) and characteristic changes
during operation (i.e. injector clogging) directly affect mixture
ratio.
Accordingly, the difference between the basic and theoretical
mixture ratios is monitored in this system. This is then computed
in terms of ``injection pulse duration'' to automatically compen-
sate for the difference between the two ratios.
FUEL INJECTION SYSTEM
Two types of systems are used.
Sequential multiport fuel injection system
Fuel is injected into each cylinder during each engine cycle
according to the firing order. This system is used when the
engine is running.
MEF025DD
MEF522D
ENGINE AND EMISSION BASIC CONTROL SYSTEM DESCRIPTIONKA
Multiport Fuel Injection (MFI) System
(Cont'd)
EC-15

Distributor Ignition (DI) System
INPUT/OUTPUT SIGNAL LINE
Camshaft position sensorcEngine speed and piston position
ECM
(ECCS
control
module)
cPower
transistor
Mass air flow sensorcAmount of intake air
Engine coolant temperature sensor
cEngine coolant temperature
Throttle position sensor
c
Throttle position
Throttle valve idle position
Vehicle speed sensor
cVehicle speed
Ignition switch
cStart signal
Intake air temperature sensor
cIntake air temperature
Neutral position switch
cGear position
Battery
cBattery voltage
SYSTEM DESCRIPTION
The ignition timing is controlled by the ECM to maintain the best
air-fuel ratio for every running condition of the engine.
The ignition timing data is stored in the ECM. This data forms the
map shown left.
The ECM detects information such as the injection pulse width
and camshaft position sensor signal. Responding to this
information, ignition signals are transmitted to the power transis-
tor.
e.g. N: 1,800 rpm, Tp: 1.50 msec
A ÉBTDC
During the following conditions, the ignition timing is revised by
the ECM according to the other data stored in the ECM.
1 At starting
2 During warm-up
3 At idle
4 When swirl control valve operates
5 Hot-engine operation
6 At acceleration
SEF742M
ENGINE AND EMISSION BASIC CONTROL SYSTEM DESCRIPTIONKA
EC-17

Air Conditioning Cut Control
INPUT/OUTPUT SIGNAL LINE
Air conditioner switchcAir conditioner ``ON'' signal
ECM
(ECCS
control
module)
cAir condi-
tioner
relayThrottle position sensorcThrottle valve opening angle
Ignition switch
cStart signal
Engine coolant temperature sensor
cEngine coolant temperature
SYSTEM DESCRIPTION
This system improves engine operation when the
air conditioner is used.
Under the following conditions, the air conditioner
is turned off.
lWhen the accelerator pedal is fully depressed
lWhen cranking the engine
lWhen the engine coolant temperature becomes
excessively high
Fuel Cut Control (at no load & high engine
speed)
INPUT/OUTPUT SIGNAL LINE
Vehicle speed sensorcVehicle speed
ECM
(ECCS
control
module)
cInjectors
Neutral position switchcNeutral position
Throttle position sensor
cThrottle position
Engine coolant temperature sensor
cEngine coolant temperature
Camshaft position sensor
cEngine speed
If the engine speed is above 3,500 rpm with no load (for
example, in neutral and engine speed over 3,500 rpm) fuel will
be cut off after some time. The exact time when the fuel is cut
off varies based on engine speed.
Fuel cut will operate until the engine speed reaches 1,500 rpm,
then fuel cut is cancelled.
NOTE:
This function is different than deceleration control listed
under multiport fuel injection on EC-14.
ENGINE AND EMISSION BASIC CONTROL SYSTEM DESCRIPTIONKA
EC-18

Idle Speed/Ignition Timing/Idle Mixture Ratio
Adjustment
PREPARATION
lMake sure that the following parts are in
good order.
(1) Battery
(2) Ignition system
(3) Engine oil and coolant levels
(4) Fuses
(5) ECM harness connector
(6) Vacuum hoses
(7) Air intake system
(Oil filler cap, oil level gauge, etc.)
(8) Fuel pressure(9) Engine compression
(10) Throttle valvelOn air conditioner equipped models,
checks should be carried out while the air
conditioner is ``OFF''.
lWhen measuring ``CO'' percentage, insert
probe more than 40 cm (15.7 in) into tail
pipe.
lTurn off headlamps, heater blower, rear
window defogger.
lKeep front wheels pointed straight ahead.
LHD MODELS
Overall inspection sequence
INSPECTION START
Perform diagnostic test mode II (Self-diagnostic results).
OK
cNG
Repair or replace.
.
Check & adjust ignition timing.
OKm
NG
Check & adjust idle
speed.
.
OKb
Check function of heated
oxygen sensor.
OK
cNG
Check harnesses of
heated oxygen sensor.
NG
cOK
Check CO%.
OK
.
cNG
Check emission control
parts and repair or
replace if necessary.
bRepair or replace har-
ness(es).
lReplace heated oxy-
gen sensor.
lCheck function of
heated oxygen sensor.
cNG
INSPECTION END
bOK
.
.
.
.
.
BASIC SERVICE PROCEDUREKA
EC-25

START
Visually check the following:lAir cleaner clogginglHoses and ducts for leakslElectrical connectorslGasketlThrottle valve and throttle position sensor operations
Start engine and warm it up until engine coolant temperature
indicator points to the middle of gauge and ensure that engine
speed is below 1,000 rpm.
Open engine hood and run engine at about 2,000 rpm for about
2 minutes under no-load.
Perform the diagnostic test mode II (Self-diagnostic results).
OKNG
Repair or replace components as necessary.
.
Run engine at about 2,000 rpm for about 2 minutes under no-
load.
Rev engine two or three times under no-load, then run engine for
about 1 minute at idle speed.
1. Select ``IGNITION TIMING ADJ'' in WORK SUPPORT
mode.
2. Touch ``START''.
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------OR----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
1. Stop engine and disconnect throttle position sensor
harness connector.
2. Start engine.
Rev engine (2,000 - 3,000 rpm) 2 or 3 times under no-load and
run engine at idle speed.
Check ignition timing with a timing light.
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
10É 2É BTDC
OK NG
VAVB
SEF146U
SEF247F
SEF051PA
SEF248F
SEF546N
.
.
.
.
.
.
.
.
.
..
BASIC SERVICE PROCEDUREKA
Idle Speed/Ignition Timing/Idle Mixture Ratio
Adjustment (Cont'd)
EC-26

VAVB
b
Adjust ignition timing to the specified value by turning dis-
tributor after loosening bolts which secure distributor.
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
10É 2É BTDC
VF
1. Select ``IGNITION TIMING ADJ'' in WORK
SUPPORT mode.
2. Touch ``START''.
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------OR ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
1. Stop engine and disconnect throttle position
sensor harness connector.
2. Start engine.
.
Check base idle speed.
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Read idle speed in ``IGN TIMING ADJ'' mode with
CONSULT.
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------OR ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Check idle speed.
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
750 25 rpm
OKNG
Rev engine (2,000 - 3,000 rpm) 2 or 3 times under no
load and run engine at idle speed.
Adjust base idle speed by turning idle speed adjusting
screw.
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
750 25 rpm
c
Touch ``Back''.
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------OR ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
1. Stop engine and connect throttle position sen-
sor harness connector.
2. Start engine.
Rev engine (2,000 - 3,000 rpm) 2 or 3 times under no
load and run engine at idle speed.
VC
SMA189AA
SEF546N
SEF147U
SEF913J
SEF602K
.
.
.
.
.
.
.
.
BASIC SERVICE PROCEDUREKA
Idle Speed/Ignition Timing/Idle Mixture Ratio
Adjustment (Cont'd)
EC-27