coolant INFINITI FX35 2006 Workshop Manual
[x] Cancel search | Manufacturer: INFINITI, Model Year: 2006, Model line: FX35, Model: INFINITI FX35 2006Pages: 4462, PDF Size: 57.74 MB
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COMBINATION METERS DI-17
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Revision: 2006 December 2006 FX35/FX45
PRELIMINARY CHECK
1. CHECK OPERATION OF SELF-DIAGNOSIS MODE (COMBINATION METER)
Perform self-diagnosis mode of combination meter. Refer to DI-15, "
OPERATION PROCEDURE" .
Does self-diagnosis function operate?
YES >> GO TO 2.
NO >> GO TO 3.
2. CHECK UNIFIED METER AND A/C AMP. (CONSULT-II)
Perform self-diagnosis of unified meter and A/C amp. Refer to DI-31, "
CONSULT-II Function (METER A/C
AMP)" .
Self-diagnosis results
No malfunction detected >> INSPECTION END
Malfunction detected >> Check applicable parts, and repair or replace corresponding parts.
3. CHECK POWER SUPPLY AND GROUND CIRCUIT OF COMBINATION METER
Check power supply and ground circuit of combination meter. Refer to DI-18, "
Power Supply and Ground Cir-
cuit Inspection" .
OK or NG
OK >> Check odo/trip meter switch. Refer to DI-24, "Odo/Trip Meter and Illumination Control Switch
Inspection" .
NG >> Repair malfunctioning part.
Symptom Chart NKS002ZM
Symptom Possible cause
Speedometer and odo/trip meter indication is malfunctioning. Refer to DI-19, "
Vehicle Speed Signal Inspection" .
Tachometer indication is malfunctioning. Refer to DI-20, "
Engine Speed Signal Inspection" .
Water temperature gauge indication is malfunctioning. Refer to DI-21, "
Engine Coolant Temperature Signal Inspection" .
Fuel gauge indication is malfunctioning. Refer to DI-21, "
Fuel Level Sensor Signal Inspection" .
Low-fuel warning lamp indication is irregular.
Shift position indicator is malfunctioning. Refer to DI-55, "
A/T Indicator Is Malfunction" .
Illumination control does not operate. Refer to
DI-24, "
Odo/Trip Meter and Illumination Control Switch
Inspection" .
Page 1271 of 4462
COMBINATION METERS DI-21
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Engine Coolant Temperature Signal InspectionNKS002ZR
Symptom: Water temperature gauge indication is malfunction.
1. CHECK COMBINATION METER INPUT SIGNAL
1. Connect CONSULT-II, and start engine.
2. Select “METER A/C AMP” on CONSULT-II.
3. Using “W TEMP METER” on “DATA MONITOR”, compare the value of “DATA MONITOR” with water temperature gauge
pointer of combination meter.
OK or NG
OK >> GO TO 2.
NG >> Replace combination meter.
2. CHECK UNIFIED METER AND A/C AMP. INPUT SIGNAL
1. Select “ENGINE” on CONSULT-II.
2. Using “COOLAN TEMP/S” on “DATA MONITOR”, print out the CONSULT-II screen.
3. Select “METER A/C AMP” on CONSULT-II.
4. Using “W TEMP METER” on “DATA MONITOR”, compare the value of “DATA MONITOR” with that of the “COOLAN TEMP/S”.
OK or NG
OK >> Perform ECM self-diagnosis. Refer to EC-119, "CON-
SULT-II Function (ENGINE)" (VQ35DE) or EC-780,
"CONSULT-II Function (ENGINE)" (VK45DE).
NG >> Replace unified meter and A/C amp. Refer to DI-37,
"Removal and Installation of Unified Meter and A/C
Amp." .
Fuel Level Sensor Signal InspectionNKS002ZS
Symptom:
Fuel gauge indication is malfunctioning.
Low-fuel warning lamp indication is irregular.
NOTE:
The following symptoms are not malfunctions.
Fuel gauge
Depending on vehicle posture or driving circumstance, the fuel level in the tank varies, and the pointer
may fluctuate.
If the vehicle is fueled with the ignition switch ON, the pointer will move slowly.
Low-fuel warning lamp
Depending on vehicle posture or driving circumstance, the fuel in the tank flows and the warning lamp ON
timing may change.
Water temperature gauge pointer Reference value of data monitor [ °C ( °F)]
Hot Approx. 130 (266)
Middle Approx. 70 - 105 (158 - 221) Cold Approx. 50 (122)
PKIA2091E
SKIA4368E
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DI-28
UNIFIED METER AND A/C AMP
Revision: 2006 December 2006 FX35/FX45
UNIFIED METER AND A/C AMPPFP:27760
System DescriptionNKS00300
For the unified meter and A/C amp., the signal required for controlling the combination meter are inte-
grated in the A/C auto amp.
The unified meter and A/C amp. corresponds to a CONSULT-II function (self-diagnosis results, CAN diag-
nosis support monitor, data monitor).
COMBINATION METER CONTROL FUNCTION
Unified meter and A/C amp. receives necessary information for combination meter from each unit by CAN
communication.
Unified meter and A/C amp. transmits a signals with communication line (TX, RX) between unified meter
and A/C amp. and combination meter.
Input/output signals between unified meter and A/C amp. and combination meter.
NOTE:
Combination meter performs fail-safe operation when unified meter and A/C amp. communication is malfunctioning. Refer to DI-8,
"FAIL-SAFE" . Unit Input Output
Unified meter and A/C amp.
Seat belt buckle switch signal (Driver's side)
Parking brake signal
Illumination control nighttime required signal
Refuel status signal
Low-fuel warning lamp condition signal
Combination meter receive error signal
Delivery destination data signal
Combination meter specifications signal
Vehicle speed signal (8-pulse)
Engine speed signal
Engine coolant temperature signal
Fuel level sensor signal (resistance value)
Malfunction indicator lamp signal
ABS warning lamp signal
Low tire pressure warning lamp signal
Brake warning lamp signal
A/T CHECK warning lamp signal
ICC warning lamp signal
Oil pressure switch signal
Door switch signal
AWD warning lamp signal
Key warning lamp signal
VDC OFF indicator lamp signal
SLIP indicator lamp signal
CRUISE indicator lamp signal
SET indicator lamp signal
High beam request signal
Turn indicator signal
Snow mode switch signal
ICC system display signal
Shift position indicator signal
Manual mode indicator signal
Manual mode gear position signal
CAN communication condition signal of A/T
Position lights request signal
Buzzer output signal
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DI-32
UNIFIED METER AND A/C AMP
Revision: 2006 December 2006 FX35/FX45
DATA MONITOR
Operation Procedure
1. Touch “DATA MONITOR” on “SELECT DIAG MODE” screen.
2. Touch either “MAIN SIGNALS” or “SELECTION FROM MENU” on the “DATA MONITOR” screen.
3. When “SELECTION FROM MENU” is selected, touch individual items to be monitored. When “MAIN SIG- NALS” is selected, main items will be monitored.
4. Touch “START”.
5. Touch “RECORD” while monitoring, then the status of the moni- tored item can be recorded. To stop recording, touch “STOP”.
Display Item List
X: Applicable
MAIN SIGNALS Monitors main signals.
SELECTION FROM MENU Selects and monitors individual signal.
SKIA4957E
Display item [Unit] MAIN
SIGNALS SELECTION
FROM MENU Contents
SPEED METER [km/h] or [mph] X X Displays the value of vehicle speed signal, which is input from
ABS actuator and electric unit (control unit).
SPEED OUTPUT [km/h] or [mph] X X Displays the value of vehicle speed signal, which is transmitted
to each unit with CAN communication.
TACHO METER [rpm] X X Displays the value of engine speed signal, which is input from
ECM.
W TEMP METER [ °C] or [ °F] X X Displays the value of engine coolant temperature signal, which
is input from ECM.
FUEL METER [lit.] X X Displays the value, which processes a resistance signal from
fuel gauge.
DISTANCE [km] or [mile] X X Displays the value, which is calculated by vehicle speed signal
from ABS actuator and electric unit (control unit), fuel gauge and
fuel consumption from ECM.
FUEL W/L [ON/OFF] X X Indicates [ON/OFF] condition of low-fuel warning lamp.
MIL [ON/OFF] X Indicates [ON/OFF] condition of malfunction indicator lamp.
AIR PRES W/L [ON/OFF] X Indicates [ON/OFF] condition of low tire pressure warning lamp.
SEAT BELT W/L [ON/OFF] X Indicates [ON/OFF] condition of seat belt warning lamp.
BUZZER [ON/OFF] X X Indicates [ON/OFF] condition of buzzer.
DOOR W/L [ON/OFF] X Indicates [ON/OFF] condition of door warning lamp.
HI-BEAM IND [ON/OFF] X Indicates [ON/OFF] condition of high beam indicator.
TURN IND [ON/OFF] X Indicates [ON/OFF] condition of turn indicator.
OIL W/L [ON/OFF] X Indicates [ON/OFF] condition of oil pressure warning lamp.
VDC/TCS IND [ON/OFF] X Indicates [ON/OFF] condition of VDC OFF indicator lamp.
ABS W/L [ON/OFF] X Indicates [ON/OFF] condition of ABS warning lamp.
SLIP IND [ON/OFF] X Indicates [ON/OFF] condition of SLIP indicator lamp.
BRAKE W/L [ON/OFF]* X Indicates [ON/OFF] condition of brake warning lamp.
KEY G W/L [ON/OFF] X Indicates [ON/OFF] condition of key warning lamp (green).
KEY R W/L [ON/OFF] X Indicates [ON/OFF] condition of key warning lamp (red).
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LANE DEPARTURE WARNING SYSTEM DI-83
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Action TestNKS00314
LDW SYSTEM RUNNING TEST
WARNING:
Be careful when performing road test.
Understand “Precautions” and “System Description” well before the road test. Refer to DI-80,
"Precautions for Lane Departure Warning (LDW) system" and DI-80, "System Description" .
Function Check
Check the LDW system operation according to the condition that the warning function works. Refer to DI-80,
"LDW SYSTEM OPERATION" .
Camera Aiming AdjustmentNKS00315
OUTLINE
Adjust the camera aiming every time the LDW camera unit is removed or installed.
CAUTION:
Place the vehicle on the level ground when the camera aiming adjustment is operated.
Follow the CONSULT-II when adjusting the camera aiming. (Camera aiming adjustment cannot be
operated without CONSULT-II.)
PREPARATION
Keep all tires inflated to correct pressures. Adjust the tire pressure to the specified pressure value.
There is no-load in vehicle. Check if coolant, engine oil are filled up to correct level and fuel tank is full.
Shift the gear into “P” position and release the parking brake.
Clean the windshield.
NOTE:
Do not place anything reflective on the upper surface of instrument panel.
TARGET SETTING
Preparation Aiming Adjustment Jig
For aiming adjustment, prepare the following jigs and targets.
PKIB4693E
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EC-7
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Revision: 2006 December 2006 FX35/FX45 CONSULT-II Reference Value in Data Monitor Mode
. 589
On Board Diagnosis Logic .................................. . 589
DTC Confirmation Procedure .............................. . 590
Wiring Diagram ................................................... . 591
Diagnostic Procedure .......................................... . 592
Component Inspection ........................................ . 595
Removal and Installation ..................................... . 595
DTC P2138 APP SENSOR .................................... . 596
Component Description ....................................... . 596
CONSULT-II Reference Value in Data Monitor Mode . 596
On Board Diagnosis Logic .................................. . 596
DTC Confirmation Procedure .............................. . 597
Wiring Diagram ................................................... . 598
Diagnostic Procedure .......................................... . 599
Component Inspection ........................................ . 603
Removal and Installation ..................................... . 603
DTC P2A00, P2A03 A/F SENSOR 1 ..................... . 604
Component Description ....................................... . 604
CONSULT-II Reference Value in Data Monitor Mode . 604
On Board Diagnosis Logic .................................. . 604
DTC Confirmation Procedure .............................. . 605
Wiring Diagram ................................................... . 606
Diagnostic Procedure .......................................... . 609
Removal and Installation ..................................... . 615
ASCD BRAKE SWITCH ........................................ . 616
Component Description ....................................... . 616
CONSULT-II Reference Value in Data Monitor Mode . 616
Wiring Diagram ................................................... . 617
Diagnostic Procedure .......................................... . 618
Component Inspection ........................................ . 622
ASCD INDICATOR ................................................ . 623
Component Description ....................................... . 623
CONSULT-II Reference Value in Data Monitor Mode . 623
Wiring Diagram ................................................... . 624
Diagnostic Procedure .......................................... . 625
ELECTRICAL LOAD SIGNAL ............................... . 626
Description .......................................................... . 626
CONSULT-II Reference Value in Data Monitor Mode . 626
Diagnostic Procedure .......................................... . 626
FUEL INJECTOR ................................................... . 628
Component Description ....................................... . 628
CONSULT-II Reference Value in Data Monitor Mode . 628
Wiring Diagram ................................................... . 629
Diagnostic Procedure .......................................... . 630
Component Inspection ........................................ . 634
Removal and Installation ..................................... . 634
FUEL PUMP .......................................................... . 635
Description .......................................................... . 635
CONSULT-II Reference Value in Data Monitor Mode . 635
Wiring Diagram ................................................... . 636 Diagnostic Procedure ..........................................
.637
Component Inspection ......................................... .640
Removal and Installation ..................................... .640
ICC BRAKE SWITCH ............................................ .641
Component Description ....................................... .641
CONSULT-II Reference Value in Data Monitor Mode .641
Wiring Diagram .................................................... .642
Diagnostic Procedure .......................................... .643
Component Inspection ......................................... .648
IGNITION SIGNAL ................................................. .649
Component Description ....................................... .649
Wiring Diagram .................................................... .650
Diagnostic Procedure .......................................... .655
Component Inspection ......................................... .660
Removal and Installation ..................................... .661
REFRIGERANT PRESSURE SENSOR ................. .662
Component Description ....................................... .662
Wiring Diagram .................................................... .663
Diagnostic Procedure .......................................... .664
Removal and Installation ..................................... .666
SNOW MODE SWITCH ......................................... .667
Description ........................................................... .667
CONSULT-II Reference Value in the Data Monitor
Mode .................................................................... .667
Wiring Diagram .................................................... .668
Diagnostic Procedure .......................................... .669
Component Inspection ......................................... .671
MIL AND DATA LINK CONNECTOR ..................... .672
Wiring Diagram .................................................... .672
SERVICE DATA AND SPECIFICATIONS (SDS) ... .674
Fuel Pressure ...................................................... .674
Idle Speed and Ignition Timing ............................ .674
Calculated Load Value ......................................... .674
Mass Air Flow Sensor .......................................... .674
Intake Air Temperature Sensor ............................ .674
Engine Coolant Temperature Sensor .................. .674
Air Fuel Ratio (A/F) Sensor 1 Heater ................... .674
Heated Oxygen sensor 2 Heater ......................... .674
Crankshaft Position Sensor (POS) ...................... .674
Camshaft Position Sensor (PHASE) ................... .674
Throttle Control Motor .......................................... .674
Fuel Injector ......................................................... .675
Fuel Pump ........................................................... .675
VK45DE
INDEX FOR DTC .................................................... .676
DTC No. Index ..................................................... .676
Alphabetical Index ............................................... .680
PRECAUTIONS ..................................................... .684
Precautions for Supplemental Restraint System
(SRS) “AIR BAG” and “SEAT BELT PRE-TEN-
SIONER” .............................................................. .684
Precautions for Procedures without Cowl Top Cover .684
On Board Diagnostic (OBD) System of Engine and
A/T ....................................................................... .684
Precaution ........................................................... .685
Page 1398 of 4462
EC-14Revision: 2006 December 2006 FX35/FX45 CONSULT-II Reference Value in Data Monitor Mode
1295
Wiring Diagram .................................................... 1296
Diagnostic Procedure .......................................... 1297
Component Inspection ......................................... 1301
ASCD INDICATOR ................................................. 1302
Component Description ....................................... 1302
CONSULT-II Reference Value in Data Monitor Mode 1302
Wiring Diagram .................................................... 1303
Diagnostic Procedure .......................................... 1304
ELECTRICAL LOAD SIGNAL ............................... 1305
Description ........................................................... 1305
CONSULT-II Reference Value in Data Monitor Mode 1305
Diagnostic Procedure .......................................... 1305
FUEL INJECTOR ................................................... 1307
Component Description ....................................... 1307
CONSULT-II Reference Value in Data Monitor Mode 1307
Wiring Diagram .................................................... 1308
Diagnostic Procedure .......................................... 1309
Component Inspection ......................................... 1313
Removal and Installation ..................................... 1313
FUEL PUMP ........................................................... 1314
Description ........................................................... 1314
CONSULT-II Reference Value in Data Monitor Mode 1314
Wiring Diagram .................................................... 1315
Diagnostic Procedure .......................................... 1316
Component Inspection ......................................... 1319
Removal and Installation ..................................... 1319
ICC BRAKE SWITCH ............................................. 1320
Component Description ....................................... 1320
CONSULT-II Reference Value in Data Monitor Mode 1320
Wiring Diagram .................................................... 1321
Diagnostic Procedure .......................................... 1322
Component Inspection ......................................... 1327
IGNITION SIGNAL ................................................. 1328
Component Description ....................................... 1328
Wiring Diagram .................................................... 1329 Diagnostic Procedure ...........................................
1334
Component Inspection ......................................... 1339
Removal and Installation ...................................... 1340
REFRIGERANT PRESSURE SENSOR ................. 1341
Component Description ....................................... 1341
Wiring Diagram .................................................... 1342
Diagnostic Procedure ........................................... 1343
Removal and Installation ...................................... 1345
SNOW MODE SWITCH .......................................... 1346
Description ........................................................... 1346
CONSULT-II Reference Value in the Data Monitor
Mode .................................................................... 1346
Wiring Diagram .................................................... 1347
Diagnostic Procedure ........................................... 1348
Component Inspection ......................................... 1350
VARIABLE INDUCTION AIR CONTROL SYSTEM
(VIAS) ..................................................................... 1351
Description ........................................................... 1351
CONSULT-II Reference Value in Data Monitor Mode 1352
Wiring Diagram .................................................... 1353
Diagnostic Procedure ........................................... 1355
Component Inspection ......................................... 1358
Removal and Installation ...................................... 1359
MIL AND DATA LINK CONNECTOR ..................... 1360
Wiring Diagram .................................................... 1360
SERVICE DATA AND SPECIFICATIONS (SDS) ... 1362
Fuel Pressure ....................................................... 1362
Idle Speed and Ignition Timing ............................. 1362
Calculated Load Value ......................................... 1362
Mass Air Flow Sensor .......................................... 1362
Intake Air Temperature Sensor ............................ 1362
Engine Coolant Temperature Sensor ................... 1362
Fuel Tank Temperature Sensor ............................ 1362
Crankshaft Position Sensor (POS) ...................... 1362
Camshaft Position Sensor (PHASE) .................... 1362
A/F Sensor 1 Heater ............................................ 1362
Heated Oxygen sensor 2 Heater ......................... 1363
Throttle Control Motor .......................................... 1363
Fuel Injector ......................................................... 1363
Fuel Pump ............................................................ 1363
Page 1413 of 4462
![INFINITI FX35 2006 Workshop Manual PREPARATION EC-29
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Revision: 2006 December 2006 FX35/FX45
Commercial Service ToolsNBS003L0
Tool name
(Kent-Moore No.) Description
Leak detector
i.e.](/img/42/57019/w960_57019-1412.png "INFINITI FX35 2006 Workshop Manual PREPARATION EC-29
[VQ35DE]
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Revision: 2006 December 2006 FX35/FX45
Commercial Service ToolsNBS003L0
Tool name
(Kent-Moore No.) Description
Leak detector
i.e.")
PREPARATION EC-29
[VQ35DE]
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Revision: 2006 December 2006 FX35/FX45
Commercial Service ToolsNBS003L0
Tool name
(Kent-Moore No.) Description
Leak detector
i.e.: (J-41416) Locating 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 1415 of 4462
![INFINITI FX35 2006 Workshop Manual ENGINE CONTROL SYSTEM EC-31
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Revision: 2006 December 2006 FX35/FX45
Multiport Fuel Injection (MFI) SystemNBS003L2
INPUT/OUTPUT SIGNAL CHART
*1: This sens](/img/42/57019/w960_57019-1414.png "INFINITI FX35 2006 Workshop Manual ENGINE CONTROL SYSTEM EC-31
[VQ35DE]
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Revision: 2006 December 2006 FX35/FX45
Multiport Fuel Injection (MFI) SystemNBS003L2
INPUT/OUTPUT SIGNAL CHART
*1: This sens")
ENGINE CONTROL SYSTEM EC-31
[VQ35DE]
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Revision: 2006 December 2006 FX35/FX45
Multiport Fuel Injection (MFI) SystemNBS003L2
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
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
control Fuel injector
Camshaft position sensor (PHASE)
Mass air flow sensor Amount of intake air
Engine coolant temperature sensor Engine coolant temperature
Air fuel ratio (A/F) 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
Air conditioner switch Air conditioner operation*
2
Wheel sensorVehicle speed*2
Page 1416 of 4462
![INFINITI FX35 2006 Workshop Manual EC-32
[VQ35DE]
ENGINE CONTROL SYSTEM
Revision: 2006 December 2006 FX35/FX45
MIXTURE RATIO FEEDBACK CONTROL (CLOSED LOOP CONTROL)
The mixture ratio feedback system provides the best air-fuel mixture ra](/img/42/57019/w960_57019-1415.png "INFINITI FX35 2006 Workshop Manual EC-32
[VQ35DE]
ENGINE CONTROL SYSTEM
Revision: 2006 December 2006 FX35/FX45
MIXTURE RATIO FEEDBACK CONTROL (CLOSED LOOP CONTROL)
The mixture ratio feedback system provides the best air-fuel mixture ra")
EC-32
[VQ35DE]
ENGINE CONTROL SYSTEM
Revision: 2006 December 2006 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 1 can then better reduce CO, HC and NOx emissions. This system uses air fuel ratio
(A/F) 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 air fuel
ratio (A/F) sensor 1, refer to EC-240, "
DTC P0131, P0151 A/F SENSOR 1" . 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 1. Even if the switching characteris-
tics of air fuel ratio (A/F) 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 air fuel ratio (A/F) sensor 1 or its circuit
Insufficient activation of air fuel ratio (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 air fuel ratio (A/F)
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., 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 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 air fuel ratio (A/F) 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.
“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.
PBIB3020E