2005 NISSAN X-TRAIL Service Repair Manual

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Page 433 of 4555

NISSAN X-TRAIL 2005 Service Repair Manual PREPARATION
EC-29
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Commercial Service ToolsEBS010L5
Tool name Description
Quick connector
releaseRemoving fuel tube quick connectors in engine
room
(A

Page 434 of 4555

NISSAN X-TRAIL 2005 Service Repair Manual EC-30
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ENGINE CONTROL SYSTEM

ENGINE CONTROL SYSTEMPFP:23710
System DiagramEBS010L6
QR20DE ENGINE MODELS
PBIB2455E

Page 435 of 4555

NISSAN X-TRAIL 2005 Service Repair Manual ENGINE CONTROL SYSTEM
EC-31
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QR25DE ENGINE MODELS
PBIB2456E

Page 436 of 4555

NISSAN X-TRAIL 2005 Service Repair Manual EC-32
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ENGINE CONTROL SYSTEM

Vacuum Hose DrawingEBS010L7
QR20DE ENGINE MODELS
Refer to EC-30, "QR20DE ENGINE MODELS" for Vacuum Control System.
PBIB0489E

Page 437 of 4555

NISSAN X-TRAIL 2005 Service Repair Manual ENGINE CONTROL SYSTEM
EC-33
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QR25DE ENGINE MODELS
Refer to EC-31, "QR25DE ENGINE MODELS" for Vacuum Control System.
PBIB1445E

Page 438 of 4555

NISSAN X-TRAIL 2005 Service Repair Manual EC-34
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ENGINE CONTROL SYSTEM

System ChartEBS010L8
*1: This sensor is not used to control the engine system under normal conditions.
*2: This input signal is sent to the ECM throu

Page 439 of 4555

NISSAN X-TRAIL 2005 Service Repair Manual ENGINE CONTROL SYSTEM
EC-35
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Multiport Fuel Injection (MFI) SystemEBS010L9
INPUT/OUTPUT SIGNAL CHART
*1: This sensor is not used to control the engine s

ENGINE CONTROL SYSTEM
EC-35
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Multiport Fuel Injection (MFI) SystemEBS010L9
INPUT/OUTPUT SIGNAL CHART
*1: This sensor is not used to control the engine system under normal conditions.
*2: This signal is sent to the ECM through CAN communication line.
*3: ECM determines the start signal status by the signals of engine speed and battery voltage.
SYSTEM DESCRIPTION
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 crankshaft position sensor and the mass air
flow sensor.
VARIOUS FUEL INJECTION INCREASE/DECREASE COMPENSATION
In addition, the amount of fuel injected is compensated to improve engine performance under various operat-
ing conditions as listed below.

During warm-up
When starting the engine
During acceleration
Hot-engine operation
When selector lever is changed from N to D (A/T models)
High-load, high-speed operation

During deceleration
During high engine speed operation
Sensor Input Signal to ECMECM
functionActuator
Crankshaft position sensor (POS)
Camshaft position sensor (PHASE)Engine speed*
3 and piston position
Fuel injec-
tion & mix-
ture ratio
controlFuel injector 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 sensor Throttle position
Accelerator pedal position sensor Accelerator pedal position
Park/neutral position (PNP) switch Gear position
Knock sensor Engine knocking condition
Battery
Battery voltage*
3
Power steering pressure sensor Power steering operation
Heated oxygen sensor 2*
1Density of oxygen in exhaust gas
Wheel sensor*
2Vehicle speed
Air conditioner switch Air conditioner operation

Page 440 of 4555

NISSAN X-TRAIL 2005 Service Repair Manual EC-36
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ENGINE CONTROL SYSTEM

MIXTURE RATIO FEEDBACK CONTROL (CLOSED LOOP CONTROL)
The mixture ratio feedback system provides the best air-fuel mixture ratio for driveability and

EC-36
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ENGINE CONTROL SYSTEM

MIXTURE RATIO FEEDBACK CONTROL (CLOSED LOOP CONTROL)
The mixture ratio feedback system provides the best air-fuel mixture ratio for driveability and emission control.
The three way catalyst (manifold) can then better reduce CO, HC and NOx emissions. This system uses
heated oxygen sensor 1 in the exhaust manifold to monitor whether the engine operation is rich or lean. The
ECM adjusts the injection pulse width according to the sensor voltage signal. For more information about
heated oxygen sensor 1, refer to EC-179, "
DTC P0132 HO2S1" . 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 (manifold). Even if the switching
characteristics of heated oxygen sensor 1 shift, the air-fuel ratio is controlled to stoichiometric by the signal
from heated oxygen sensor 2.
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.
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
After shifting from N to D (A/T models)
When starting the engine
MIXTURE RATIO SELF-LEARNING CONTROL
The mixture ratio feedback control system monitors the mixture ratio signal transmitted from heated oxygen
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 orig-
inally 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 compensate for the difference between
the two ratios.
“Fuel trim” refers to the feedback compensation value compared against the basic injection duration. Fuel trim
includes short term fuel trim and long term fuel trim.
“Short term fuel trim” is the short-term fuel compensation used to maintain the mixture ratio at its theoretical
value. The signal from heated oxygen sensor 1 indicates whether the mixture ratio is RICH or LEAN compared
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.
“Long term fuel trim” 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.
PBIB0121E

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