NISSAN PICK-UP 2001 Repair Manual

SEC226D
ENGINE AND EMISSION CONTROL OVERALL SYSTEMYD25DDTi
Engine Control Component Parts Location
(Cont'd)
EC-3406

SEC227D
ENGINE AND EMISSION CONTROL OVERALL SYSTEMYD25DDTi
Engine Control Component Parts Location
(Cont'd)
EC-3407

Circuit Diagram
GEC273A
ENGINE AND EMISSION CONTROL OVERALL SYSTEMYD25DDTi
EC-3408

System Diagram
SEC239D
ENGINE AND EMISSION CONTROL OVERALL SYSTEMYD25DDTi
EC-3409

System Chart
Input (Sensor) ECM Function Output (Actuator)
+Electronic control fuel injection pump
+Crankshaft position sensor (TDC)
+Engine coolant temperature sensor
+Accelerator position sensor
+Accelerator position switch
+Park/Neutral position (PNP) switch
+Ignition switch
+Battery voltage
+Vehicle speed sensor
+Air conditioner switch
+Stop lamp switch
+Charge air pressure sensor
+Intake air temperature sensorFuel injection control Electronic control fuel injection pump
Fuel injection timing control Electronic control fuel injection pump
Fuel cut control Electronic control fuel injection pump
Glow control system Glow relay & glow lamp
On board diagnostic system MIL (On the instrument panel)
EGR volume control EGR volume control valve
Cooling fan control Cooling fan relay
Air conditioning cut control Air conditioner relay
ENGINE AND EMISSION CONTROL OVERALL SYSTEMYD25DDTi
EC-3410

Fuel Injection Control System
DESCRIPTION
System description
Three types of fuel injection control are provided to accommodate engine operating conditions; normal
control, idle control and start control. The ECM determines the appropriate fuel injection control. Under each
control, the amount of fuel injected is compensated to improve engine performance.
Pulse signals are exchanged between ECM and electronic control fuel injection pump (control unit is built-
in). The fuel injection pump control unit performs duty control on the spill valve (built into the fuel injection
pump) according to the input signals to compensate the amount of fuel injected to the preset value.
Start control
Input/output signal chart
Sensor Input Signal to ECM ECM Function Actuator
Engine coolant temperature sensor Engine coolant temperature
Fuel injection con-
trol (start control)Electronic control fuel injec-
tion pump Crankshaft position sensor (TDC) Engine speed
Ignition switch Start signal
When the ECM receives a start signal from the ignition switch,
the ECM adapts the fuel injection system for the start control.
The amount of fuel injected at engine starting is a preset program
value in the ECM. The program is determined by the engine
speed and engine coolant temperature.
For better startability under cool engine conditions, the lower the
coolant temperature becomes, the greater the amount of fuel
injected. The ECM ends the start control when the engine speed
reaches the specific value, and shifts the control to the normal
or idle control.
Idle control
Input/output signal chart
Sensor Input Signal to ECM ECM Function Actuator
Engine coolant temperature sensor Engine coolant temperature
Fuel injection con-
trol (Idle control)Electronic control fuel injec-
tion pump Crankshaft position sensor (TDC) Engine speed
Park/Neutral position (PNP) switch Gear position
Battery Battery voltage
Accelerator position switch Idle position
Vehicle speed sensor Vehicle speed
Air conditioner switch Air conditioner signal
Intake air temperature sensor Intake air temperature
When the ECM determines that the engine speed is at idle, the fuel injection system is adapted for the idle
control. The ECM regulates the amount of fuel injected corresponding to changes in load applied to the
engine to keep engine speed constant. The ECM also provides the system with a fast idle control in response
to the engine coolant temperature and heat up switch signal.
SEF648S
ENGINE AND EMISSION BASIC CONTROL SYSTEM
DESCRIPTIONYD25DDTi
EC-3411

Normal control
Input/output signal chart
Sensor Input Signal to ECM ECM Function Actuator
Crankshaft position sensor (TDC) Engine speed
Fuel injection con-
trol (Normal con-
trol)Electronic control fuel injec-
tion pump Accelerator position sensor Accelerator position
Vehicle speed sensor Vehicle speed
The amount of fuel injected under normal driving conditions is
determined according to sensor signals. The crankshaft position
sensor (TDC) detects engine speed and the accelerator position
sensor detects accelerator position. These sensors send signals
to the ECM.
The fuel injection data, predetermined by correlation between
various engine speeds and accelerator positions, are stored in
the ECM memory, forming a map. The ECM determines the
optimal amount of fuel to be injected using the sensor signals in
comparison with the map.
Maximum amount control
Input/output signal chart
Sensor Input Signal to ECM ECM Function Actuator
Engine coolant temperature sensor Engine coolant temperature
Fuel injection con-
trol (Maximum
amount control)Electronic control fuel injec-
tion pump Crankshaft position sensor (TDC) Engine speed
Accelerator position sensor Accelerator position
The maximum injection amount is controlled to an optimum by the engine speed, intake air amount, engine
coolant temperature, and accelerator opening in accordance with the driving conditions.
This prevents the oversupply of the injection amount caused by decreased air density at a high altitude or
during a system failure.
Deceleration control
Input/output signal chart
Sensor Input Signal to ECM ECM Function Actuator
Accelerator position switch Accelerator positionFuel injection con-
trol (Deceleration
control)Electronic control fuel injec-
tion pump
Crankshaft position sensor (TDC) Engine speed
The ECM sends a fuel cut signal to the electronic control fuel injection pump during deceleration for better
fuel efficiency. The ECM determines the time of deceleration according to signals from the accelerator posi-
tion switch and crankshaft position sensor (TDC).
SEF649S
ENGINE AND EMISSION BASIC CONTROL SYSTEM
DESCRIPTIONYD25DDTi
Fuel Injection Control System (Cont'd)
EC-3412

Fuel Injection Timing Control System
DESCRIPTION
The target fuel injection timing in accordance with the engine speed and the fuel injection amount are
recorded as a map in the ECM beforehand. The ECM and the injection pump control unit exchange signals
and perform feedback control for optimum injection timing in accordance with the map.
Air Conditioning Cut Control
DESCRIPTION
Input/output signal chart
Sensor Input Signal to ECM ECM Function Actuator
Air conditioner switch Air conditioner ªONº signal
Air conditioner cut
controlAir conditioner relay Accelerator position sensor Accelerator position
Vehicle speed sensor Vehicle speed
Engine coolant temperature sensor Engine coolant temperature
System description
This system improves acceleration when the air conditioner is used.
When the accelerator pedal is fully depressed, the air conditioner is turned off for a few seconds.
When engine coolant temperature becomes excessively high, the air conditioner is turned off. This contin-
ues until the engine coolant temperature returns to normal.
Fuel Cut Control (at no load & high engine
speed)
DESCRIPTION
Input/output signal chart
Sensor Input Signal to ECM ECM Function Actuator
Vehicle speed sensor Vehicle speed
Fuel cut controlElectronic control fuel injec-
tion pump Park/Neutral position (PNP) switch Neutral position
Accelerator position switch Accelerator position
Engine coolant temperature sensor Engine coolant temperature
Crankshaft position sensor (TDC) Engine speed
If the engine speed is above 2,700 rpm with no load (for example, in neutral and engine speed over 2,700
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 ªFuel Injection Control Systemº,
EC-3411.
ENGINE AND EMISSION BASIC CONTROL SYSTEM
DESCRIPTIONYD25DDTi
EC-3413

Crankcase Ventilation System
DESCRIPTION
In this system, blow-by gas is sucked into the air inlet pipe after
oil separation by oil separator in the rocker cover.
INSPECTION
Ventilation hose
1. Check hoses and hose connections for leaks.
2. Disconnect all hoses and clean with compressed air. If any
hose cannot be freed of obstructions, replace.
SEC240D
SEC692
ENGINE AND EMISSION BASIC CONTROL SYSTEM
DESCRIPTIONYD25DDTi
EC-3414

Injection Tube and Injection Nozzle
REMOVAL AND INSTALLATION
CAUTION:
+Do not disassemble injection nozzle assembly. If NG,
replace injection nozzle assembly.
+Plug flare nut with a cap or rag so that no dust enters the
nozzle. Cover nozzle tip for protection of needle.
Injection Tube
Removal
1. Mark the cylinder Nos. to the injection tubes, then disconnect
them.
+Marking should be made at proper locations and by the
proper method, so that they are not erased by fuel, etc.
2. Remove the clamps, then disconnect the tubes one by one.
+The intake manifold is removed for explanation in the figure.
JEC263D
JEC264D
BASIC SERVICE PROCEDUREYD25DDTi
EC-3415