2014 NISSAN TEANA width

SYSTEMEC-45
< SYSTEM DESCRIPTION > [QR25DE]
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MIXTURE RATIO FEEDBACK CONTROL (CLOSED LOOP CONTROL)
The mixture ratio feedback system prov
ides the best air-fuel mixture ratio for driveability and emission control.
The three way catalyst (manifold) can then better r educe CO, HC and NOx emissions. This system uses A/F
sensor 1 in the exhaust manifold to monitor whether t he engine operation is rich or lean. The ECM adjusts the
injection pulse width according to the sensor voltage si gnal. For more information about A/F sensor 1, refer to
EC-32, "Air Fuel Ratio (A/F) Sensor 1"
. This maintains the mixture rati o 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 th ree way catalyst (manifold). Even if the switching
characteristics of A/F sensor 1 shift, the air-fuel rati o is controlled to stoichiometric by the signal from heated
oxygen sensor 2.
• Open Loop Control
The open loop system condition refers to when the EC M 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 A/F sensor 1 or its circuit
- Insufficient activation of A/F sensor 1 at low engine coolant temperature
- High engine coolant temperature
- During warm-up
- After shifting from N to D
- When starting the engine
MIXTURE RATIO SELF-LEARNING CONTROL
The mixture ratio feedback control system monitors the mixture ratio signal transmitted from A/F sensor 1.
This feedback signal is then sent to the ECM. The ECM cont rols the basic mixture ratio as close to the theoret-
ical mixture ratio as possible. However, the basic mi xture ratio is not necessarily controlled as originally
designed. Both manufacturing differences (i.e., mass air flow sensor hot wire) and characteristic changes dur-
ing operation (i.e., fuel 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 co mpared 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 compensati on used to maintain the mixture ratio at its theoretical
value. The signal from A/F sensor 1 indicates whether the mixture ratio is RICH or LEAN compared to the the-
oretical 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 ca rried 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.
PBIB2793E
Revision: November 20132014 Altima NAMRevision: November 20132014 Altima NAM

EC-46
< SYSTEM DESCRIPTION >[QR25DE]
SYSTEM
FUEL INJECTION TIMING
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.
• Simultaneous Multiport Fuel Injection System
Fuel is injected simultaneously into all four cylinder s 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-OFF
Fuel to each cylinder is cut off during deceleration, operation of the engine at excessively high speeds or oper-
ation of the vehicle at excessively high speeds.
MULTIPORT FUEL INJECTION SYSTEM : S ystem Description (with manual air con-
ditioner)
INFOID:0000000009462094
SYSTEM DIAGRAM
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). T he amount of fuel injected is a program value in the
ECM memory. The program value is preset by engi ne operating conditions. These conditions are determined
SEF337W
JPBIA6221GB
Revision: November 20132014 Altima NAMRevision: November 20132014 Altima NAM

SYSTEMEC-47
< SYSTEM DESCRIPTION > [QR25DE]
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by input signals (for engine speed and intake air) from t
he crankshaft position sensor (POS), camshaft position
sensor (PHASE) and the mass air flow sensor.
VARIOUS FUEL INJECTION INCREASE/DECREASE COMPENSATION
In addition, the amount of fuel injected is compens ated 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
• High-load, high-speed operation

• During deceleration
• During high engine speed operation
MIXTURE RATIO FEEDBACK CONTROL (CLOSED LOOP CONTROL)
The mixture ratio feedback system prov ides the best air-fuel mixture ratio for driveability and emission control.
The three way catalyst (manifold) can then better r educe CO, HC and NOx emissions. This system uses A/F
sensor 1 in the exhaust manifold to monitor whether t he engine operation is rich or lean. The ECM adjusts the
injection pulse width according to the sensor voltage si gnal. For more information about A/F sensor 1, refer to
EC-32, "Air Fuel Ratio (A/F) Sensor 1"
. This maintains the mixture rati o 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 th ree way catalyst (manifold). Even if the switching
characteristics of A/F sensor 1 shift, the air-fuel rati o is controlled to stoichiometric by the signal from heated
oxygen sensor 2.
• Open Loop Control
The open loop system condition refers to when the EC M 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 A/F sensor 1 or its circuit
- Insufficient activation of A/F sensor 1 at low engine coolant temperature
- High engine coolant temperature
- During warm-up
- After shifting from N to D
- When starting the engine
MIXTURE RATIO SELF-LEARNING CONTROL
The mixture ratio feedback control system monitors the mixture ratio signal transmitted from A/F sensor 1.
This feedback signal is then sent to the ECM. The ECM cont rols the basic mixture ratio as close to the theoret-
ical mixture ratio as possible. However, the basic mi xture ratio is not necessarily controlled as originally
designed. Both manufacturing differences (i.e., mass air flow sensor hot wire) and characteristic changes dur-
ing operation (i.e., fuel 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 co mpared against the basic injection duration. Fuel trim
includes short term fuel trim and long term fuel trim.
PBIB2793E
Revision: November 20132014 Altima NAMRevision: November 20132014 Altima NAM

EC-48
< SYSTEM DESCRIPTION >[QR25DE]
SYSTEM
“Short term fuel trim” is the short-term fuel compensati
on used to maintain the mixture ratio at its theoretical
value. The signal from A/F sensor 1 indicates whether the mixture ratio is RICH or LEAN compared to the the-
oretical 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 carri ed out long-term to compensate for continual deviation
of the short term fuel trim from t he central value. Such deviation will occur due to individual engine differences,
wear over time and changes in the usage environment.
FUEL INJECTION TIMING
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.
• Simultaneous Multiport Fuel Injection System Fuel is injected simultaneously into all four cylinder s 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-OFF
Fuel to each cylinder is cut off during deceleration, operation of the engine at excessively high speeds or oper-
ation of the vehicle at excessively high speeds.
ELECTRIC IGNITION SYSTEM
ELECTRIC IGNITION SYSTEM : System DescriptionINFOID:0000000009462095
SYSTEM DIAGRAM
SYSTEM DESCRIPTION
Firing order: 1 - 3 - 4 - 2
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.
SEF337W
JPBIA3193GB
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SYSTEMEC-49
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The ECM receives information such as the injecti
on pulse width and camshaft position sensor (PHASE) sig-
nal. Computing this information, ignition si gnals are transmitted to the power transistor.
During the following conditions, the ignition timing is revi sed 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.
INTAKE VALVE TIMING CONTROL
INTAKE VALVE TIMING CONTROL : System DescriptionINFOID:0000000009462096
INTAKE VALVE TIMING CONTROL
System Diagram
Input/Output Signal Chart
*: This signal is sent to the ECM through CAN communication line
JPBIA4760GB
Sensor Input signal to ECM ECM function Actuator
Crankshaft position sensor (POS) Engine speed and piston position
Intake valve
timing control Intake valve timing control
solenoid valve
Camshaft position sensor (PHASE)
Engine oil temperature sensor Engine oil temperature
Engine coolant temperature sensor Engine coolant temperature
Combination meter Vehicle speed*
Revision: November 20132014 Altima NAMRevision: November 20132014 Altima NAM

DIAGNOSIS SYSTEM (ECM)EC-79
< SYSTEM DESCRIPTION > [QR25DE]
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OMonitored item Unit Monitor Item
Selection
Description Remarks
ECU
IN-
PUT
SIG-
NALS MAIN
SIG-NAL
S
ENG SPEED rpm ×ו Indicates the engine speed computed
from the signal of the crankshaft position
sensor (POS) and camshaft position sen-
sor (PHASE). • Accuracy becomes poor if en-
gine speed drops below the
idle rpm.
• If the signal is interrupted while
the engine is running, an ab-
normal value may be indicat-
ed.
MAS A/F SE-B1 V ×ו The signal voltage of the mass air flow
sensor is displayed. • When the engine is stopped, a
certain value is indicated.
• When engine is running, spec- ification range is indicated in
“SPEC”.
B/FUEL SCHDL ms ×ו “Base fuel schedule” indicates the fuel in-
jection pulse width programmed into
ECM, prior to any learned on board cor-
rection. • When engine is running, spec-
ification range is indicated in
“SPEC”.
A/F ALPHA-B1 % • The mean value of the air-fuel ratio feed-
back correction factor per cycle is indicat-
ed. • When the engine is stopped, a
certain value is indicated.
• When engine is running, spec-
ification range is indicated in
“SPEC”.
• This data also includes the
data for the air-fuel ratio learn-
ing control.
COOLAN TEMP/S °C or °F ×× • The engine coolant temperature (deter-
mined by the signal voltage of the engine
coolant temperature sensor) is dis-
played. • When the engine coolant tem-
perature sensor is open or
short-circuited, ECM enters
fail-safe mode. The engine
coolant temperature deter-
mined by the ECM is dis-
played.
A/F SEN1 (B1) V ×ו The A/F signal computed from the input
signal of the air fuel ratio (A/F) sensor 1
is displayed.
HO2S2 (B1) V ×ו The signal voltage of the heated oxygen
sensor 2 is displayed.
HO2S2 MNTR(B1) RICH/LEAN ו Display of heated oxygen sensor 2 sig-
nal.
- RICH: means the amount of oxygen after
three way catalyst is relatively small.
- LEAN: means the amount of oxygen after three way catalyst is relatively large. • When the engine is stopped, a
certain value is indicated.
VHCL SPEED SE km/h or mph ×ו The vehicle speed computed from the
vehicle speed signal sent from combina-
tion meter is displayed.
BATTERY VOLT V • The power supply voltage of ECM is dis-
played.
ACCEL SEN 1
V• The accelerator pedal position sensor
signal voltage is displayed. • ACCEL SEN 2 signal is con-
verted by ECM internally.
Thus, it differs from ECM ter-
minal voltage signal.
ACCEL SEN 2
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EC-80
< SYSTEM DESCRIPTION >[QR25DE]
DIAGNOSIS SYSTEM (ECM)
TP SEN 1-B1
V××
• The throttle position sensor signal volt-age is displayed. • TP SEN 2-B1 signal is convert-
ed by ECM internally. Thus, it
differs from ECM terminal volt-
age signal.
TP SEN 2-B1
××
FUEL T/TMP SE °C or °F • The fuel temperature (determined by the
signal voltage of the fuel tank tempera-
ture sensor) is displayed.
EVAP SYS PRES V • The signal voltage of EVAP control sys-
tem pressure sensor is displayed.
FUEL LEVEL SE V ו The signal voltage of the fuel level sensor
is displayed.
START SIGNAL On/Off • Indicates start signal status [ON/OFF]
computed by the ECM according to the
signals of engine speed and battery volt-
age. • After starting the engine, [OFF]
is displayed regardless of the
starter signal.
CLSD THL POS On/Off ×ו Indicates idle position [ON/OFF] comput-
ed by ECM according to the accelerator
pedal position sensor signal.
AIR COND SIG On/Off ×ו Indicates [ON/OFF] condition of the air
conditioner switch as determined by the
air conditioner signal.
PW/ST SIGNAL On/Off ×ו [ON/OFF] condition of the power steering
system (determined by the signal sent
from EPS control unit) is indicated.
LOAD SIGNAL On/Off ×ו Indicates [ON/OFF] condition from the
electrical load signal.
- On: Rear window defogger switch is ON and/or lighting switch is in 2nd position.
- Off: Both rear window defogger switch
and lighting switch are OFF.
IGNITION SW On/Off ×ו Indicates [ON/OFF] condition from igni-
tion switch signal.
HEATER FAN SW On/Off ו Indicates [ON/OFF] condition from the
heater fan switch signal.
BRAKE SW On/Off • Indicates [ON/OFF] condition from the
stop lamp switch signal.
INJ PULSE-B1 msec • Indicates the actual fuel injection pulse
width compensated by ECM according to
the input signals. • When the engine is stopped, a
certain computed value is indi-
cated.
IGN TIMING BTDC ו Indicates the ignition timing computed by
ECM according to the input signals. • When the engine is stopped, a
certain value is indicated.
CAL/LD VALUE % • “Calculated load value” indicates the val-
ue of the current air flow divided by peak
air flow.
MASS AIRFLOW g/s • Indicates the mass air flow computed by
ECM according to the signal voltage of
the mass air flow sensor.
Monitored item Unit
Monitor Item
Selection
Description Remarks
ECU
IN-
PUT
SIG-
NALS MAIN
SIG-
NAL S
Revision: November 20132014 Altima NAMRevision: November 20132014 Altima NAM

TROUBLE DIAGNOSIS - SPECIFICATION VALUEEC-195
< DTC/CIRCUIT DIAGNOSIS > [QR25DE]
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DTC/CIRCUIT DIAGNOSIS
TROUBLE DIAGNOSIS - SPECIFICATION VALUE
DescriptionINFOID:0000000009462149
The specification (SP) value indicates the tolerance of
the value that is displayed in “SPEC” of “DATA MONI-
TOR” mode of CONSULT during normal operation of the Engine Control System. When the value in “SPEC” of
“DATA MONITOR” mode is within the SP value, the E ngine Control System is confirmed OK. When the value
in “SPEC” of “DATA MONITOR” mode is NOT within t he SP value, the Engine Control System may have one
or more malfunctions.
The SP value is used to detect malfunctions that may af fect the Engine Control System, but will not light the
MIL.
The SP value will be displayed for the following three items:
• B/FUEL SCHDL (The fuel injection pulse width programmed into ECM prior to any learned on board correc- tion)
• A/F ALPHA-B1 (The mean value of air-fuel ratio feedback correction factor per cycle)
• MAS A/F SE-B1 (The signal voltage of the mass air flow sensor)
Component Function CheckINFOID:0000000009462150
1.START
Make sure that all of the following conditions are satisfied.
• Vehicle driven distance: More than 5,000 km (3,107 miles)
• Barometric pressure: 98.3 - 104.3 kPa (1.003 - 1.064 kg/cm
2, 14.25 - 15.12 psi)
• Atmospheric temperature: 20 - 30 °C (68 - 86 °F)
• Engine coolant temperature: 75 - 95 °C (167 - 203 °F)
• Transmission: Warmed-up
- After the engine is warmed up to normal operating tem perature, drive vehicle until “ATF TEMP SEN” (CVT
fluid temperature sensor signal) indicates more than 60 °C (140 °F).
• Electrical load: Not applied*
• Engine speed: Idle
*: Rear window defogger switch, air conditioner switch, lighting switch are OFF. Steering wheel is straight
ahead.
>> GO TO 2.
2.PERFORM “SPEC” OF “DATA MONITOR” MODE
With CONSULT
NOTE:
Perform “SPEC” in “DATA MONITOR” mode in maximum scale display.
1. Perform EC-170, "Work Procedure"
.
2. Select “B/FUEL SCHDL”, “A/F ALPHA-B1” and “MAS A/F SE-B1” in “SPEC” of “DATA MONITOR” mode
with CONSULT.
3. Make sure that monitor items are within the SP value.
Is the inspection result normal?
YES >> END
NO >> Proceed to EC-196, "Diagnosis Procedure"
.
Revision: November 20132014 Altima NAMRevision: November 20132014 Altima NAM