2001 NISSAN PICK-UP Repair Manual

Multiport Fuel Injection (MFI) System
DESCRIPTIONNEEC0014Input/Output Signal ChartNEEC0014S01
Sensor Input Signal to ECMECM func-
tionActuator
Camshaft position sensor Engine speed and piston position
Fuel injec-
tion & mix-
ture ratio
controlInjector Mass air flow sensor Amount of intake air
Engine coolant temperature sensor Engine coolant temperature
Heated oxygen sensor 1 Density of oxygen in exhaust gas
Throttle position sensorThrottle position
Throttle valve idle position
PNP switch Gear position
Vehicle speed sensor Vehicle speed
Ignition switch Start signal
Air conditioner switch Air conditioner operation
Knock sensor Engine knocking condition
Battery Battery voltage
Power steering oil pressure switch Power steering operation
Heated oxygen sensor 2* Density of oxygen in exhaust gas
* Under normal conditions, this sensor is not for engine control operation.
Basic Multiport Fuel Injection SystemNEEC0014S02The 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 CompensationNEEC0014S03In addition, the amount of fuel injected is compensated to improve engine performance under various oper-
ating conditions as listed below.

+During warm-up
+When starting the engine
+During acceleration
+Hot-engine operation
+High-load, high-speed operation

+During deceleration
+During high engine speed operation
ENGINE AND EMISSION BASIC CONTROL SYSTEM
DESCRIPTION
KA24DE (EURO OBD)
Multiport Fuel Injection (MFI) System
EC-3024

Mixture Ratio Feedback Control (Closed loop control)NEEC0014S04
SEC303D
The mixture ratio feedback system provides the best air-fuel mixture ratio for driveability and emission con-
trol. The three way catalyst can then better reduce CO, HC and NOx emissions. This system uses a heated
oxygen sensor 1 in the exhaust manifold to monitor if the engine operation is rich or lean. The ECM adjusts
the injection pulse width according to the sensor voltage signal. For more information about the heated oxy-
gen sensor 1, refer to EC-3213. This maintains the mixture ratio within the range of stoichiometric (ideal air-
fuel mixture).
This stage is referred to as the closed loop control condition.
Heated oxygen sensor 2 is located downstream of the three way catalyst. Even if the switching characteris-
tics of the heated oxygen sensor 1 shift, the air-fuel ratio is controlled to stoichiometric by the signal from the
heated oxygen sensor 2.
Open Loop ControlNEEC0014S05The 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.
+Deceleration and acceleration
+High-load, high-speed operation
+Malfunction of heated oxygen sensor 1 or its circuit
+Insufficient activation of heated oxygen sensor 1 at low engine coolant temperature
+High engine coolant temperature
+During warm-up
+When starting the engine
Mixture Ratio Self-learning ControlNEEC0014S06The mixture ratio feedback control system monitors the mixture ratio signal transmitted from the heated oxy-
gen sensor 1. 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 controlled as
originally designed. Both manufacturing differences (i.e., mass air flow sensor hot film) 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 ªinjection pulse durationº to automatically compensate for the difference between
the two ratios.
ªFuel trimº refers to the feedback compensation value compared against the basic injection duration. Fuel trim
includes short term fuel trim and long term fuel trim.
ªShort term fuel trimº is the short-term fuel compensation used to maintain the mixture ratio at its theoretical
value. The signal from the heated oxygen sensor 1 indicates whether the mixture ratio is RICH or LEAN com-
pared to the theoretical value. The signal then triggers a reduction in fuel volume if the mixture ratio is rich,
and an increase in fuel volume if it is lean.
ªLong term fuel trimº is overall fuel compensation carried out long-term to compensate for continual deviation
of the short term fuel trim from the central value. Such deviation will occur due to individual engine differences,
wear over time and changes in the usage environment.
ENGINE AND EMISSION BASIC CONTROL SYSTEM
DESCRIPTION
KA24DE (EURO OBD)
Multiport Fuel Injection (MFI) System
EC-3025

Fuel Injection TimingNEEC0014S07
SEF337W
Two types of systems are used.
Sequential Multiport Fuel Injection System
NEEC0014S0701Fuel is injected into each cylinder during each engine cycle according to the firing order. This system is used
when the engine is running.
Simultaneous Multiport Fuel Injection System
NEEC0014S0702Fuel is injected simultaneously into all four cylinders twice each engine cycle. In other words, pulse signals of
the same width are simultaneously transmitted from the ECM.
The four injectors will then receive the signals two times for each engine cycle.
This system is used when the engine is being started and/or if the fail-safe system (CPU) is operating.
Fuel Shut-offNEEC0014S08Fuel to each cylinder is cut off during deceleration or operation of the engine at excessively high speeds.
Distributor Ignition (DI) System
DESCRIPTIONNEEC0015Input/Output Signal ChartNEEC0015S01
Sensor Input Signal to ECMECM func-
tionActuator
Camshaft position sensor Engine speed and piston position
Ignition tim-
ing controlPower transistor Mass air flow sensor Amount of intake air
Engine coolant temperature sensor Engine coolant temperature
Throttle position sensorThrottle position
Throttle valve idle position
Vehicle speed sensor Vehicle speed
Ignition switch Start signal
Knock sensor Engine knocking
PNP switch Gear position
Battery Battery voltage
ENGINE AND EMISSION BASIC CONTROL SYSTEM
DESCRIPTION
KA24DE (EURO OBD)
Multiport Fuel Injection (MFI) System
EC-3026

System DescriptionNEEC0015S02
SEF742M
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 above.
The ECM receives information such as the injection pulse width and camshaft position sensor signal. Com-
puting this information, ignition signals are transmitted to the power transistor.
e.g., N: 1,800 rpm, Tp: 1.50 msec
AÉBTDC
During the following conditions, the ignition timing is revised by the ECM according to the other data stored
in the ECM.
+At starting
+During warm-up
+At idle
+At low battery voltage
+During acceleration
The knock sensor retard system is designed only for emergencies. The basic ignition timing is programmed
within the anti-knocking zone, if recommended fuel is used under dry conditions. The retard system does not
operate under normal driving conditions.
If engine knocking occurs, the knock sensor monitors the condition. The signal is transmitted to the ECM. The
ECM retards the ignition timing to eliminate the knocking condition.
ENGINE AND EMISSION BASIC CONTROL SYSTEM
DESCRIPTION
KA24DE (EURO OBD)
Distributor Ignition (DI) System
EC-3027

Air Conditioning Cut Control
DESCRIPTION=NEEC0016Input/Output Signal ChartNEEC0016S01
Sensor Input Signal to ECMECM func-
tionActuator
Air conditioner switch Air conditioner ªONº signal
Air condi-
tioner cut
controlAir conditioner relay Throttle position sensor Throttle valve opening angle
Camshaft position sensor Engine speed
Engine coolant temperature sensor Engine coolant temperature
Ignition switch Start signal
Vehicle speed sensor Vehicle speed
Power steering oil pressure switch Power steering operation
System DescriptionNEEC0016S02This system improves engine operation when the air conditioner is used.
Under the following conditions, the air conditioner is turned off.
+When the accelerator pedal is fully depressed.
+When cranking the engine.
+When the engine coolant temperature becomes excessively high.
+When operating power steering and air conditioner during low engine speed or when fully releasing accel-
erator pedal.
+When engine speed is excessively low.
Fuel Cut Control (at no load & high engine
speed)
DESCRIPTIONNEEC0017Input/Output Signal ChartNEEC0017S01
Sensor Input Signal to ECMECM func-
tionActuator
Vehicle speed sensor Vehicle speed
Fuel cut
controlInjectors PNP switch Neutral position
Throttle position sensor Throttle position
Camshaft position sensor Engine speed
If the engine speed is above 3,000 rpm with no load, (for example, in Neutral and engine speed over 3,000
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 from deceleration control listed under ªMultiport Fuel Injection (MFI) Systemº,
EC-3024.
ENGINE AND EMISSION BASIC CONTROL SYSTEM
DESCRIPTION
KA24DE (EURO OBD)
Air Conditioning Cut Control
EC-3028

Evaporative Emission System
DESCRIPTION=NEEC0018
SEC310D
The evaporative emission system is used to reduce hydrocarbons emitted into the atmosphere from the fuel
system. This reduction of hydrocarbons is accomplished by activated charcoals in the EVAP canister.
The fuel vapor in the sealed fuel tank is led into the EVAP canister which contains activated carbon and the
vapor is stored there when the engine is not operating or when refueling to the fuel tank.
The vapor in the EVAP canister is purged by the air through the purge line to the intake manifold when the
engine is operating.
EVAP canister purge volume control solenoid valve is controlled by ECM. When the engine operates, the flow
rate of vapor controlled by EVAP canister purge volume control solenoid valve is proportionally regulated as
the air flow increases.
EVAP canister purge volume control solenoid valve also shuts off the vapor purge line during decelerating and
idling.
SEF917W
INSPECTIONNEEC0019EVAP CanisterNEEC0019S01Check EVAP canister as follows:
1. Block port B. Orally blow air through port A. Check that air
flows freely through port C with check valve resistance.
2. Block port A. Orally blow air through port B. Check that air
flows freely through port C.
ENGINE AND EMISSION BASIC CONTROL SYSTEM
DESCRIPTION
KA24DE (EURO OBD)
Evaporative Emission System
EC-3029

SEF427N
SEF943S
Fuel Tank Vacuum Relief Valve (Built into fuel filler cap)NEEC0019S031. Wipe clean valve housing.
2. Check valve opening pressure and vacuum.
Pressure:
16.0 - 20.0 kPa (0.16 - 0.20 bar, 0.163 - 0.204 kg/cm
2,
2.32 - 2.90 psi)
Vacuum:
þ6.0 to þ3.5 kPa (þ0.06 to þ0.35 bar, þ0.061 to þ0.036
kg/cm
2, þ0.87 to þ0.51 psi)
3. If out of specification, replace fuel filler cap as an assembly.
CAUTION:
Use only a genuine NISSAN fuel filler cap as a replacement. If
an incorrect fuel filler cap is used, the MI may come on.
Evaporative Emission (EVAP) Canister Purge Volume
Control Solenoid Valve
NEEC0019S06Refer to EC-3283.
Checking EVAP Vapor LinesNEEC0019S131. Visually inspect vapor lines for leaks, cracks, damage, loose
connections, chafing and deterioration.
2. Inspect vacuum relief valve of fuel tank filler cap for clogging,
sticking, etc. Refer to EC-3030.
ENGINE AND EMISSION BASIC CONTROL SYSTEM
DESCRIPTION
KA24DE (EURO OBD)
Evaporative Emission System
EC-3030

EVAPORATIVE EMISSION LINE DRAWING=NEEC0020
SEC266D
ENGINE AND EMISSION BASIC CONTROL SYSTEM
DESCRIPTION
KA24DE (EURO OBD)
Evaporative Emission System
EC-3031