coolant temperature INFINITI FX35 2004 Repair Manual
[x] Cancel search | Manufacturer: INFINITI, Model Year: 2004, Model line: FX35, Model: INFINITI FX35 2004Pages: 4449, PDF Size: 99.66 MB
Page 1817 of 4449
![INFINITI FX35 2004 Repair Manual EC-476
[VQ35DE]
DTC P1217 ENGINE OVER TEMPERATURE
Revision: 2004 November 2004 FX35/FX45
WITH CONSULT-II
1. Check the coolant level in the reservoir tank and radiator.
Allow engine to cool before che INFINITI FX35 2004 Repair Manual EC-476
[VQ35DE]
DTC P1217 ENGINE OVER TEMPERATURE
Revision: 2004 November 2004 FX35/FX45
WITH CONSULT-II
1. Check the coolant level in the reservoir tank and radiator.
Allow engine to cool before che](/img/42/57021/w960_57021-1816.png)
EC-476
[VQ35DE]
DTC P1217 ENGINE OVER TEMPERATURE
Revision: 2004 November 2004 FX35/FX45
WITH CONSULT-II
1. Check the coolant level in the reservoir tank and radiator.
Allow engine to cool before checking coolant level.
If the coolant level in the reservoir tank and/or radiator is below
the proper range, skip the following steps and go to EC-479,
"PROCEDURE A" .
2. Confirm whether customer filled the coolant or not. If customer
filled the coolant, skip the following steps and go to EC-479,
"PROCEDURE A" .
3. Turn ignition switch ON.
4. Perform “COOLING FAN” in “ACTIVE TEST” mode with CON-
SULT-II.
5. If the results are NG, go to EC-479, "
PROCEDURE A" .
WITH GST
1. Check the coolant level in the reservoir tank and radiator.
Allow engine to cool before checking coolant level.
If the coolant level in the reservoir tank and/or radiator is below
the proper range, skip the following steps and go to EC-479,
"PROCEDURE A" .
2. Confirm whether customer filled the coolant or not. If customer
filled the coolant, skip the following steps and go to EC-479,
"PROCEDURE A" .
3. Perform IPDM E/R auto active test and check cooling fan motors operation, refer to PG-24, "
Auto Active
Te s t"
4. If NG, go to EC-479, "PROCEDURE A" .
SEF621W
SEF646X
SEF621W
Page 1821 of 4449
![INFINITI FX35 2004 Repair Manual EC-480
[VQ35DE]
DTC P1217 ENGINE OVER TEMPERATURE
Revision: 2004 November 2004 FX35/FX45
5. CHECK RADIATOR CAP
Apply pressure to cap with a tester.
OK or NG
OK >> GO TO 6.
NG >> Replace radiator cap.
INFINITI FX35 2004 Repair Manual EC-480
[VQ35DE]
DTC P1217 ENGINE OVER TEMPERATURE
Revision: 2004 November 2004 FX35/FX45
5. CHECK RADIATOR CAP
Apply pressure to cap with a tester.
OK or NG
OK >> GO TO 6.
NG >> Replace radiator cap.](/img/42/57021/w960_57021-1820.png)
EC-480
[VQ35DE]
DTC P1217 ENGINE OVER TEMPERATURE
Revision: 2004 November 2004 FX35/FX45
5. CHECK RADIATOR CAP
Apply pressure to cap with a tester.
OK or NG
OK >> GO TO 6.
NG >> Replace radiator cap.
6. CHECK THERMOSTAT
1. Check valve seating condition at normal room temperatures.
It should seat tightly.
2. Check valve opening temperature and valve lift.
3. Check if valve is closed at 5°C (9°F) below valve opening tem-
perature.
For details, refer to CO-26, "
WATER INLET AND THERMO-
STAT ASSEMBLY" .
OK or NG
OK >> GO TO 7.
NG >> Replace thermostat
7. CHECK ENGINE COOLANT TEMPERATURE SENSOR
Refer to EC-189, "
Component Inspection" .
OK or NG
OK >> GO TO 8.
NG >> Replace engine coolant temperature sensor.
8. CHECK MAIN 12 CAUSES
If the cause cannot be isolated, go to EC-484, "
Main 12 Causes of Overheating" .
>>INSPECTION END Radiator cap relief pressure:
59 - 98 kPa (0.6 - 1.0 kg/cm
2
, 9 - 14 psi)
SLC755A
Valve opening temperature: 76.5°C (170°F) [standard]
Valve lift: More than 8.6 mm/90°C
(0.339 in/194°F)
SLC343
Page 1825 of 4449
![INFINITI FX35 2004 Repair Manual EC-484
[VQ35DE]
DTC P1217 ENGINE OVER TEMPERATURE
Revision: 2004 November 2004 FX35/FX45
Main 12 Causes of OverheatingABS006VE
*1: Turn the ignition switch ON.
*2: Engine running at 3,000 rpm for 10 m INFINITI FX35 2004 Repair Manual EC-484
[VQ35DE]
DTC P1217 ENGINE OVER TEMPERATURE
Revision: 2004 November 2004 FX35/FX45
Main 12 Causes of OverheatingABS006VE
*1: Turn the ignition switch ON.
*2: Engine running at 3,000 rpm for 10 m](/img/42/57021/w960_57021-1824.png)
EC-484
[VQ35DE]
DTC P1217 ENGINE OVER TEMPERATURE
Revision: 2004 November 2004 FX35/FX45
Main 12 Causes of OverheatingABS006VE
*1: Turn the ignition switch ON.
*2: Engine running at 3,000 rpm for 10 minutes.
*3: Drive at 90 km/h (55 MPH) for 30 minutes and then let idle for 10 minutes.
*4: After 60 minutes of cool down time.
For more information, refer to CO-7, "
OVERHEATING CAUSE ANALYSIS" .
Component InspectionABS006VF
COOLING FAN MOTORS-1 AND -2
1. Disconnect cooling fan motor harness connectors.
2. Supply cooling fan motor terminals with battery voltage and
check operation.
Cooling fan motor should operate.
If NG, replace cooling fan motor.
Engine Step Inspection item Equipment Standard Reference page
OFF 1
Blocked radiator
Blocked condenser
Blocked radiator grille
Blocked bumper
Visual No blocking —
2
Coolant mixtureCoolant tester 50 - 50% coolant mixtureMA-13
3Coolant levelVisual Coolant up to MAX level
in reservoir tank and radi-
ator filler neckCO-11
4Radiator capPressure tester 59 - 98 kPa
(0.6 - 1.0 kg/cm2 , 9 - 14
psi) (Limit)CO-15
ON*25Coolant leaksVisual No leaksCO-11
ON*26ThermostatTouch the upper and
lower radiator hosesBoth hoses should be hotCO-26
ON*17Cooling fanCONSULT-II Operating See trouble diagnosis for
DTC P1217 (EC-472
).
OFF 8
Combustion gas leakColor checker chemical
tester 4 Gas analyzerNegative —
ON*
39Coolant temperature
gaugeVisual Gauge less than 3/4
when driving—
Coolant overflow to
reservoir tankVisual No overflow during driving
and idlingCO-11
OFF*410Coolant return from
reservoir tank to radia-
torVisual Should be initial level in
reservoir tankCO-11
OFF 11Cylinder headStraight gauge feeler
gauge0.1 mm (0.004 in) Maxi-
mum distortion (warping)EM-100
12Cylinder block and pis-
tonsVisual No scuffing on cylinder
walls or pistonEM-120
Cooling fan speedCooling fan motor terminals
(+) (−)
Middle (MID)1 3 and 4
2 3 and 4
1 and 2 3
1 and 2 4
High (HI) 1 and 2 3 and 4
SEF734W
Page 1835 of 4449
![INFINITI FX35 2004 Repair Manual EC-494
[VQ35DE]
DTC P1444 EVAP CANISTER PURGE VOLUME CONTROL SOLENOID VALVE
Revision: 2004 November 2004 FX35/FX45
DTC P1444 EVAP CANISTER PURGE VOLUME CONTROL SOLENOID VALVE
PFP:14920
DescriptionABS0 INFINITI FX35 2004 Repair Manual EC-494
[VQ35DE]
DTC P1444 EVAP CANISTER PURGE VOLUME CONTROL SOLENOID VALVE
Revision: 2004 November 2004 FX35/FX45
DTC P1444 EVAP CANISTER PURGE VOLUME CONTROL SOLENOID VALVE
PFP:14920
DescriptionABS0](/img/42/57021/w960_57021-1834.png)
EC-494
[VQ35DE]
DTC P1444 EVAP CANISTER PURGE VOLUME CONTROL SOLENOID VALVE
Revision: 2004 November 2004 FX35/FX45
DTC P1444 EVAP CANISTER PURGE VOLUME CONTROL SOLENOID VALVE
PFP:14920
DescriptionABS006VU
SYSTEM DESCRIPTION
*1:ECM determines the start signal status by the signals of engine speed and battery voltage.
*2: This signal is sent to the ECM through CAN communication line.
This system controls flow rate of fuel vapor from the EVAP canister. The opening of the vapor by-pass pas-
sage in the EVAP canister purge volume control solenoid valve changes to control the flow rate. The EVAP
canister purge volume control solenoid valve repeats ON/OFF operation according to the signal sent from the
ECM. The opening of the valve varies for optimum engine control. The optimum value stored in the ECM is
determined by considering various engine conditions. When the engine is operating, the flow rate of fuel vapor
from the EVAP canister is regulated as the air flow changes.
COMPONENT DESCRIPTION
The EVAP canister purge volume control solenoid valve uses a ON/
OFF duty to control the flow rate of fuel vapor from the EVAP canis-
ter. The EVAP canister purge volume control solenoid valve is
moved by ON/OFF pulses from the ECM. The longer the ON pulse,
the greater the amount of fuel vapor that will flow through the valve.
CONSULT-II Reference Value in Data Monitor ModeABS006VV
Specification data are reference values.
Sensor Input Signal to ECM ECM function Actuator
Crankshaft position sensor (POS)
Camshaft position sensor (PHASE)Engine speed*
1
EVAP canister
purge flow controlEVAP canister purge vol-
ume control solenoid valve Mass air flow sensor Amount of intake air
Engine coolant temperature sensor Engine coolant temperature
Battery
Battery voltage*
1
Throttle position sensor Throttle position
Accelerator pedal position sensor Accelerator pedal position
Heated oxygen sensor 1Density of oxygen in exhaust gas
(Mixture ratio feedback signal)
Fuel tank temperature sensor Fuel temperature in fuel tank
Wheel sensor*
2Vehicle speed
SEF337U
MONITOR ITEM CONDITION SPECIFICATION
PURG VOL C/V
Engine: After warming up
Shift lever: P or N
Air conditioner switch: OFF
No-loadIdle 0%
2,000 rpm —
Page 1998 of 4449
![INFINITI FX35 2004 Repair Manual AUTOMATIC SPEED CONTROL DEVICE (ASCD)
EC-657
[VQ35DE]
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Revision: 2004 November 2004 FX35/FX45
AUTOMATIC SPEED CONTROL DEVICE (ASCD)PFP:18930
System DescriptionABS006ZG
INPUT/O INFINITI FX35 2004 Repair Manual AUTOMATIC SPEED CONTROL DEVICE (ASCD)
EC-657
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Revision: 2004 November 2004 FX35/FX45
AUTOMATIC SPEED CONTROL DEVICE (ASCD)PFP:18930
System DescriptionABS006ZG
INPUT/O](/img/42/57021/w960_57021-1997.png)
AUTOMATIC SPEED CONTROL DEVICE (ASCD)
EC-657
[VQ35DE]
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Revision: 2004 November 2004 FX35/FX45
AUTOMATIC SPEED CONTROL DEVICE (ASCD)PFP:18930
System DescriptionABS006ZG
INPUT/OUTPUT SIGNAL CHART
*: This signal is sent to the ECM through CAN communication line.
BASIC ASCD SYSTEM
Refer to Owner's Manual for ASCD operating instructions.
Automatic Speed Control Device (ASCD) allows a driver to keep vehicle at predetermined constant speed
without depressing accelerator pedal. Driver can set vehicle speed in advance between approximately 40 km/
h (25 MPH) and 144 km/h (89 MPH).
ECM controls throttle angle of electric throttle control actuator to regulate engine speed.
Operation status of ASCD is indicated by CRUISE indicator and SET indicator in combination meter. If any
malfunction occurs in ASCD system, it automatically deactivates control.
SET OPERATION
Press ON/OFF(MAIN)) switch. (The CRUISE indicator in combination meter illuminates.)
When vehicle speed reaches a desired speed between approximately 40 km/h (25 MPH) and 144 km/h (89
MPH), press COAST/SET switch. (Then SET indicator in combination meter illuminates.)
ACCEL OPERATION
If the ACCEL/RESUME switch is pressed during cruise control driving, increase the vehicle speed until the
switch is released or vehicle speed reaches maximum speed controlled by the system.
And then ASCD will keep the new set speed.
CANCEL OPERATION
When any of following conditions exist, cruise operation will be canceled.
CANCEL switch is pressed
More than 2 switches at ASCD steering switch are pressed at the same time (Set speed will be cleared)
Brake pedal is depressed
Selector lever is changed to N, P, R position
Vehicle speed decreased to 13 km/h (8 MPH) lower than the set speed
VDC/TCS system is operated
When the ECM detects any of the following conditions, the ECM will cancel the cruise operation and inform
the driver by blinking indicator lamp.
Engine coolant temperature is slightly higher than the normal operating temperature, CRUISE lamp may
blink slowly.
When the engine coolant temperature decreases to the normal operating temperature, CRUISE lamp will
stop blinking and the cruise operation will be able to work by depressing COAST/SET switch or ACCEL/
RESUME switch.
Malfunction for some self-diagnoses regarding ASCD control: SET lamp will blink quickly.
If ON/OFF(MAIN) switch is turned to OFF during ASCD is activated, all of ASCD operations will be canceled
and vehicle speed memory will be erased.
COAST OPERATION
When the COAST/SET switch is pressed during cruise control driving, decrease vehicle set speed until the
switch is released. And then ASCD will keep the new set speed.
Sensor Input signal to ECM ECM function Actuator
ASCD brake switch Brake pedal operation
ASCD vehicle speed controlElectric throttle control
actuator Stop lamp switch Brake pedal operation
ASCD steering switch ASCD steering switch operation
Park/Neutral position (PNP)
switchGear position
Unified meter and A/C amp.* Vehicle speed
TCM* Powertrain revolution
Page 2001 of 4449
![INFINITI FX35 2004 Repair Manual EC-660
[VQ35DE]
SERVICE DATA AND SPECIFICATIONS (SDS)
Revision: 2004 November 2004 FX35/FX45
SERVICE DATA AND SPECIFICATIONS (SDS)PFP:00030
Fuel PressureABS006ZI
Idle Speed and Ignition TimingABS006ZJ INFINITI FX35 2004 Repair Manual EC-660
[VQ35DE]
SERVICE DATA AND SPECIFICATIONS (SDS)
Revision: 2004 November 2004 FX35/FX45
SERVICE DATA AND SPECIFICATIONS (SDS)PFP:00030
Fuel PressureABS006ZI
Idle Speed and Ignition TimingABS006ZJ](/img/42/57021/w960_57021-2000.png)
EC-660
[VQ35DE]
SERVICE DATA AND SPECIFICATIONS (SDS)
Revision: 2004 November 2004 FX35/FX45
SERVICE DATA AND SPECIFICATIONS (SDS)PFP:00030
Fuel PressureABS006ZI
Idle Speed and Ignition TimingABS006ZJ
*1: Under the following conditions:
Air conditioner switch: OFF
Electric load: OFF (Lights, heater fan & rear window defogger)
Steering wheel: Kept in straight-ahead position
Calculated Load ValueABS006ZK
Mass Air Flow SensorABS006ZL
*: Engine is warmed up to normal operating temperature and running under no-load.
Intake Air Temperature SensorABS006ZM
Engine Coolant Temperature SensorABS006ZN
Heated Oxygen Sensor 1 HeaterABS006ZO
Heated Oxygen sensor 2 HeaterABS006ZP
Crankshaft Position Sensor (POS)ABS006ZQ
Refer to EC-307, "Component Inspection" .
Camshaft Position Sensor (PHASE)ABS006ZR
Refer to EC-315, "Component Inspection" .
Throttle Control MotorABS006ZS
Fuel pressure at idling kPa (kg/cm2 , psi)Approximately 350 (3.57, 51)
Target idle speed
No-load*1 (in P or N position)650±50 rpm
Air conditioner: ON In P or N position 775 rpm or more
Ignition timing In P or N position 15° ± 5° BTDC
Calculated load value% (Using CONSULT-II or GST)
At idle5 - 35
At 2,500 rpm5 - 35
Supply voltageBattery voltage (11 - 14V)
Output voltage at idle1.1 - 1.5*V
Mass air flow (Using CONSULT-II or GST)2.0 - 6.0 g·m/sec at idle*
7.0 - 20.0 g·m/sec at 2,500 rpm*
Temperature °C (°F) Resistance kΩ
25 (77)1.94 - 2.06
80 (176)0.295 - 0.349
Temperature °C (°F) Resistance kΩ
20 (68)2.1 - 2.9
50 (122)0.68 - 1.00
90 (194)0.236 - 0.260
Resistance [at 25°C (77°F)] 3.3 - 4.0Ω
Resistance [at 25°C (77°F)] 5.0 - 7.0Ω
Resistance [at 25°C (77°F)] Approximately 1 - 15Ω
Page 2016 of 4449
![INFINITI FX35 2004 Repair Manual PREPARATION
EC-675
[VK45DE]
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Revision: 2004 November 2004 FX35/FX45
Commercial Service ToolsABS00BZ2
Tool name
(Kent-Moore No.)Description
Leak detector
i.e.: (J-41416)Locati INFINITI FX35 2004 Repair Manual PREPARATION
EC-675
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Revision: 2004 November 2004 FX35/FX45
Commercial Service ToolsABS00BZ2
Tool name
(Kent-Moore No.)Description
Leak detector
i.e.: (J-41416)Locati](/img/42/57021/w960_57021-2015.png)
PREPARATION
EC-675
[VK45DE]
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Revision: 2004 November 2004 FX35/FX45
Commercial Service ToolsABS00BZ2
Tool name
(Kent-Moore No.)Description
Leak detector
i.e.: (J-41416)Locating the EVAP leak
EVAP service port
adapter
i.e.: (J-41413-OBD)Applying positive pressure through EVAP service
port
Fuel filler cap adapter
i.e.: (MLR-8382)Checking fuel tank vacuum relief valve opening
pressure
Socket wrench Removing and installing engine coolant
temperature sensor
Oxygen sensor thread
cleaner
i.e.: (J-43897-18)
(J-43897-12)Reconditioning the exhaust system threads
before installing a new oxygen sensor. Use with
anti-seize lubricant shown below.
a: 18 mm diameter with pitch 1.5 mm for
Zirconia Oxygen Sensor
b: 12 mm diameter with pitch 1.25 mm for
Titania Oxygen Sensor
Anti-seize lubricant
i.e.: (Permatex
TM
133AR or equivalent
meeting MIL
specification MIL-A-
907)Lubricating oxygen sensor thread cleaning tool
when reconditioning exhaust system threads.
S-NT703
S-NT704
S-NT815
S-NT705
AEM488
S-NT779
Page 2019 of 4449
![INFINITI FX35 2004 Repair Manual EC-678
[VK45DE]
ENGINE CONTROL SYSTEM
Revision: 2004 November 2004 FX35/FX45
System ChartABS00BZ5
*1: This sensor is not used to control the engine system. This is used only for the on board diagnosis INFINITI FX35 2004 Repair Manual EC-678
[VK45DE]
ENGINE CONTROL SYSTEM
Revision: 2004 November 2004 FX35/FX45
System ChartABS00BZ5
*1: This sensor is not used to control the engine system. This is used only for the on board diagnosis](/img/42/57021/w960_57021-2018.png)
EC-678
[VK45DE]
ENGINE CONTROL SYSTEM
Revision: 2004 November 2004 FX35/FX45
System ChartABS00BZ5
*1: This sensor is not used to control the engine system. This is used only for the on board diagnosis.
*2: This sensor is not used to control the engine system under normal conditions.
*3: This input signal is sent to the ECM through CAN communication line.
*4: This output signal is sent from the ECM through CAN communication line.Input (Sensor) ECM Function Output (Actuator)
Camshaft position sensor (PHASE)
Crankshaft position sensor (POS)
Intake valve timing control position sensor
Mass air flow sensor
Engine coolant temperature sensor
Heated oxygen sensor 1
Throttle position sensor
Accelerator pedal position sensor
Park/neutral position (PNP) switch
Intake air temperature sensor
Power steering pressure sensor
Ignition switch
Battery voltage
Knock sensor
Refrigerant pressure sensor
Stop lamp switch
ICC steering switch
ICC brake switch
ASCD steering switch
ASCD brake switch
Fuel level sensor*1 *3
EVAP control system pressure sensor
Fuel tank temperature sensor*1
Heated oxygen sensor 2*2
TCM (Transmission control module)*3
ABS actuator and electric unit (control unit)*3
ICC unit*3
Air conditioner switch*3
Wheel sensor*3
Electrical load signal*3
Fuel injection & mixture ratio control Fuel injector
Electronic ignition system Power transistor
Nissan torque demand control system
Electric throttle control actuator
Fuel injector
Fuel pump control Fuel pump relay
ICC vehicle speed control
Electric throttle control actuator
ASCD vehicle speed control
On board diagnostic system
MIL (On the instrument panel)*
4
Power valve control VIAS control solenoid valve
Intake valve timing controlIntake valve timing control solenoid
valve
Heated oxygen sensor 1 heater control Heated oxygen sensor 1 heater
Heated oxygen sensor 2 heater control Heated oxygen sensor 2 heater
EVAP canister purge flow controlEVAP canister purge volume control
solenoid valve
Air conditioning cut control
Air conditioner relay*
4
Cooling fan control
Cooling fan relay*4
ON BOARD DIAGNOSIS for EVAP system EVAP canister vent control valve
Page 2020 of 4449
![INFINITI FX35 2004 Repair Manual ENGINE CONTROL SYSTEM
EC-679
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Revision: 2004 November 2004 FX35/FX45
Multiport Fuel Injection (MFI) SystemABS00BZ6
INPUT/OUTPUT SIGNAL CHART
*1: This sensor is not us INFINITI FX35 2004 Repair Manual ENGINE CONTROL SYSTEM
EC-679
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Revision: 2004 November 2004 FX35/FX45
Multiport Fuel Injection (MFI) SystemABS00BZ6
INPUT/OUTPUT SIGNAL CHART
*1: This sensor is not us](/img/42/57021/w960_57021-2019.png)
ENGINE CONTROL SYSTEM
EC-679
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Multiport Fuel Injection (MFI) SystemABS00BZ6
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 (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 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
High-load, high-speed operation
During deceleration
During high engine speed operation
Sensor Input signal to ECM ECM function Actuator
Crankshaft position sensor (POS)
Engine speed*
3
Piston position
Fuel injection
& mixture ratio
controlFuel injector Camshaft position sensor (PHASE)
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
ABS actuator and electric unit (control unit)*
2VDC/TCS operation command
Air conditioner switch*
2Air conditioner operation
Wheel sensor*
2Vehicle speed
Page 2021 of 4449
![INFINITI FX35 2004 Repair Manual EC-680
[VK45DE]
ENGINE CONTROL SYSTEM
Revision: 2004 November 2004 FX35/FX45
MIXTURE RATIO FEEDBACK CONTROL (CLOSED LOOP CONTROL)
The mixture ratio feedback system provides the best air-fuel mixture r INFINITI FX35 2004 Repair Manual EC-680
[VK45DE]
ENGINE CONTROL SYSTEM
Revision: 2004 November 2004 FX35/FX45
MIXTURE RATIO FEEDBACK CONTROL (CLOSED LOOP CONTROL)
The mixture ratio feedback system provides the best air-fuel mixture r](/img/42/57021/w960_57021-2020.png)
EC-680
[VK45DE]
ENGINE CONTROL SYSTEM
Revision: 2004 November 2004 FX35/FX45
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-863
. 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
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 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 “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