2004 INFINITI FX35 mass air flow sensor

RADIATOR
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[VK45DE]
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Revision: 2004 November 2004 FX35/FX45
RADIATORPFP:21400
Removal and InstallationABS006JS
WARNING:
Never remove radiator cap when engine is hot. Serious burns could occur from high-pressure engine
coolant escaping from thermostat housing.
REMOVAL
1. Remove engine cover with power tool. Refer to EM-168, "ENGINE ROOM COVER" .
2. Remove engine front undercover with power tool.
3. Drain engine coolant from radiator. Refer to CO-36, "
Changing Engine Coolant" .
CAUTION:

Perform this step when engine is cold.

Do not spill engine coolant on drive belts.
4. Remove air duct (inlet), air cleaner case and mass air flow sensor assembly. Refer to EM-172, "
AIR
CLEANER AND AIR DUCT" .
5. Remove radiator hoses (upper and lower).
CAUTION:
Be careful not to allow engine coolant to drive belts.
6. Disconnect A/T fluid cooler hoses.
1. Radiator 2. Upper mount bracket 3. Mounting rubber
4. Radiator hose (lower) 5. Radiator drain plug 6. O-ring
7. A/T fluid cooler hose 8. Radiator hose (upper) 9. Reservoir tank hose
10. Reservoir tank cap 11. Reservoir tank 12. Radiator shroud (lower)
13. Radiator shroud
PBIC1531E

EC-7
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Revision: 2004 November 2004 FX35/FX45Component Inspection ......................................... 575
Removal and Installation ...................................... 575
DTC P2138 APP SENSOR ..................................... 576
Component Description ........................................ 576
CONSULT-II Reference Value in Data Monitor Mode
. 576
On Board Diagnosis Logic ................................... 576
DTC Confirmation Procedure ............................... 577
Wiring Diagram .................................................... 578
Diagnostic Procedure ........................................... 579
Component Inspection ......................................... 584
Removal and Installation ...................................... 584
IGNITION SIGNAL .................................................. 585
Component Description ........................................ 585
Wiring Diagram .................................................... 586
Diagnostic Procedure ........................................... 591
Component Inspection ......................................... 595
Removal and Installation ...................................... 596
INJECTOR CIRCUIT ............................................... 597
Component Description ........................................ 597
CONSULT-II Reference Value in Data Monitor Mode
. 597
Wiring Diagram .................................................... 598
Diagnostic Procedure ........................................... 599
Component Inspection ......................................... 602
Removal and Installation ...................................... 602
FUEL PUMP CIRCUIT ............................................ 603
Description ........................................................... 603
CONSULT-II Reference Value in Data Monitor Mode
. 603
Wiring Diagram .................................................... 604
Diagnostic Procedure ........................................... 605
Component Inspection ......................................... 608
Removal and Installation ...................................... 608
REFRIGERANT PRESSURE SENSOR ................. 609
Component Description ........................................ 609
Wiring Diagram .................................................... 610
Diagnostic Procedure ............................................ 611
Removal and Installation ...................................... 613
ELECTRICAL LOAD SIGNAL ................................ 614
Description ........................................................... 614
CONSULT-II Reference Value in Data Monitor Mode
. 614
Diagnostic Procedure ........................................... 614
ICC BRAKE SWITCH ............................................. 615
Component Description ........................................ 615
CONSULT-II Reference Value in Data Monitor Mode
. 615
Wiring Diagram .................................................... 616
Diagnostic Procedure ........................................... 617
Component Inspection ......................................... 622
ASCD BRAKE SWITCH ......................................... 624
Component Description ........................................ 624
CONSULT-II Reference Value in Data Monitor Mode
. 624
Wiring Diagram .................................................... 625
Diagnostic Procedure ........................................... 626
Component Inspection ......................................... 631ASCD INDICATOR ..................................................632
Component Description ........................................632
CONSULT-II Reference Value in Data Monitor Mode
.632
Wiring Diagram .....................................................633
Diagnostic Procedure ...........................................634
SNOW MODE SWITCH ..........................................635
Description ............................................................635
CONSULT-II Reference Value in the Data Monitor
Mode .....................................................................635
Wiring Diagram .....................................................636
Diagnostic Procedure ...........................................637
Component Inspection ..........................................640
MIL AND DATA LINK CONNECTOR ......................641
Wiring Diagram .....................................................641
EVAPORATIVE EMISSION SYSTEM .....................643
Description ............................................................643
Component Inspection ..........................................646
Removal and Installation ......................................647
How to Detect Fuel Vapor Leakage ......................647
ON BOARD REFUELING VAPOR RECOVERY
(ORVR) ....................................................................650
System Description ...............................................650
Diagnostic Procedure ...........................................651
Component Inspection ..........................................653
POSITIVE CRANKCASE VENTILATION ...............655
Description ............................................................655
Component Inspection ..........................................655
AUTOMATIC SPEED CONTROL DEVICE (ASCD) .657
System Description ...............................................657
Component Description ........................................659
SERVICE DATA AND SPECIFICATIONS (SDS) ....660
Fuel Pressure .......................................................660
Idle Speed and Ignition Timing .............................660
Calculated Load Value ..........................................660
Mass Air Flow Sensor ...........................................660
Intake Air Temperature Sensor .............................660
Engine Coolant Temperature Sensor ...................660
Heated Oxygen Sensor 1 Heater .........................660
Heated Oxygen sensor 2 Heater ..........................660
Crankshaft Position Sensor (POS) .......................660
Camshaft Position Sensor (PHASE) ....................660
Throttle Control Motor ...........................................660
Injector ..................................................................661
Fuel Pump ............................................................661
VK45DE
INDEX FOR DTC .....................................................662
Alphabetical Index ................................................662
DTC No. Index ......................................................665
PRECAUTIONS ......................................................670
Precautions for Supplemental Restraint System
(SRS) “AIR BAG” and “SEAT BELT PRE-TEN-
SIONER” ...............................................................670
On Board Diagnostic (OBD) System of Engine and
A/T ........................................................................670
Precaution ............................................................670
Wiring Diagrams and Trouble Diagnosis ..............673

EC-14Revision: 2004 November 2004 FX35/FX45CONSULT-II Reference Value in Data Monitor Mode
1255
Wiring Diagram ....................................................1256
Diagnostic Procedure ..........................................1257
Component Inspection .........................................1260
Removal and Installation .....................................1261
IGNITION SIGNAL .................................................1262
Component Description .......................................1262
Wiring Diagram ....................................................1263
Diagnostic Procedure ..........................................1268
Component Inspection .........................................1272
Removal and Installation .....................................1273
INJECTOR CIRCUIT ..............................................1274
Component Description .......................................1274
CONSULT-II Reference Value in Data Monitor Mode
1274
Wiring Diagram ....................................................1275
Diagnostic Procedure ..........................................1276
Component Inspection .........................................1279
Removal and Installation .....................................1279
FUEL PUMP CIRCUIT ...........................................1280
Description ...........................................................1280
CONSULT-II Reference Value in Data Monitor Mode
1280
Wiring Diagram ....................................................1281
Diagnostic Procedure ..........................................1282
Component Inspection .........................................1285
Removal and Installation .....................................1286
REFRIGERANT PRESSURE SENSOR .................1287
Component Description .......................................1287
Wiring Diagram ....................................................1288
Diagnostic Procedure ..........................................1289
Removal and Installation .....................................1291
ELECTRICAL LOAD SIGNAL ...............................1292
Description ...........................................................1292
CONSULT-II Reference Value in Data Monitor Mode
1292
Diagnostic Procedure ..........................................1292
ICC BRAKE SWITCH .............................................1293
Component Description .......................................1293
CONSULT-II Reference Value in Data Monitor Mode
1293
Wiring Diagram ....................................................1294
Diagnostic Procedure ..........................................1295
Component Inspection .........................................1301
ASCD BRAKE SWITCH .........................................1302
Component Description .......................................1302
CONSULT-II Reference Value in Data Monitor Mode
1302Wiring Diagram ....................................................1303
Diagnostic Procedure ...........................................1304
Component Inspection .........................................1308
ASCD INDICATOR .................................................1309
Component Description .......................................1309
CONSULT-II Reference Value in Data Monitor Mode
1309
Wiring Diagram ....................................................1310
Diagnostic Procedure ...........................................1311
SNOW MODE SWITCH ..........................................1312
Description ...........................................................1312
CONSULT-II Reference Value in the Data Monitor
Mode ....................................................................1312
Wiring Diagram ....................................................1313
Diagnostic Procedure ...........................................1314
Component Inspection .........................................1317
MIL AND DATA LINK CONNECTOR .....................1318
Wiring Diagram ....................................................1318
EVAPORATIVE EMISSION SYSTEM ....................1320
Description ...........................................................1320
Component Inspection .........................................1323
Removal and Installation ......................................1324
How to Detect Fuel Vapor Leakage .....................1324
ON BOARD REFUELING VAPOR RECOVERY
(ORVR) ...................................................................1327
System Description ..............................................1327
Diagnostic Procedure ...........................................1328
Component Inspection .........................................1330
POSITIVE CRANKCASE VENTILATION ...............1332
Description ...........................................................1332
Component Inspection .........................................1332
AUTOMATIC SPEED CONTROL DEVICE (ASCD) 1334
System Description ..............................................1334
Component Description .......................................1335
SERVICE DATA AND SPECIFICATIONS (SDS) ...1336
Fuel Pressure .......................................................1336
Idle Speed and Ignition Timing .............................1336
Calculated Load Value .........................................1336
Mass Air Flow Sensor ..........................................1336
Intake Air Temperature Sensor ............................1336
Engine Coolant Temperature Sensor ...................1336
Heated Oxygen Sensor 1 Heater .........................1336
Heated Oxygen Sensor 2 Heater .........................1336
Crankshaft Position Sensor (POS) ......................1336
Camshaft Position Sensor (PHASE) ....................1336
Throttle Control Motor ..........................................1336
Injector .................................................................1337
Fuel Pump ............................................................1337

EC-24
[VQ35DE]
PRECAUTIONS
Revision: 2004 November 2004 FX35/FX45

Do not disassemble ECM.

If a battery cable is disconnected, the memory will return to
the ECM value.
The ECM will now start to self-control at its initial value.
Engine operation can vary slightly when the terminal is dis-
connected. However, this is not an indication of a malfunc-
tion. Do not replace parts because of a slight variation.

When connecting ECM harness connector, fasten it
securely with a lever as far as it will go as shown in the fig-
ure.

When connecting or disconnecting pin connectors into or
from ECM, take care not to damage pin terminals (bend or
break).
Make sure that there are not any bends or breaks on ECM
pin terminal, when connecting pin connectors.

Securely connect ECM harness connectors.
A poor connection can cause an extremely high (surge)
voltage to develop in coil and condenser, thus resulting in
damage to ICs.

Keep engine control system harness at least 10 cm (4 in)
away from adjacent harness, to prevent engine control sys-
tem malfunctions due to receiving external noise, degraded
operation of ICs, etc.

Keep engine control system parts and harness dry.

Before replacing ECM, perform “ECM Terminals and Refer-
ence Value” inspection and make sure ECM functions prop-
erly. Refer to EC-100
.

Handle mass air flow sensor carefully to avoid damage.

Do not disassemble mass air flow sensor.

Do not clean mass air flow sensor with any type of deter-
gent.

Do not disassemble electric throttle control actuator.

Even a slight leak in the air intake system can cause seri-
ous incidents.

Do not shock or jar the camshaft position sensor (PHASE),
crankshaft position sensor (POS).
PBIB1164E
PBIB1512E
PBIB0090E
MEF040D

ENGINE CONTROL SYSTEM
EC-31
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Revision: 2004 November 2004 FX35/FX45
System ChartABS006K6
*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)

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
Fuel pump control Fuel pump relay
ICC vehicle speed control Electric throttle control actuator
ASCD vehicle speed control Electric throttle control actuator
On board diagnostic system
MIL (On the instrument panel)*
4
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

EC-32
[VQ35DE]
ENGINE CONTROL SYSTEM
Revision: 2004 November 2004 FX35/FX45
Multiport Fuel Injection (MFI) SystemABS006K7
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
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
Air conditioner switch*
2Air conditioner operation
Wheel sensor*
2Vehicle speed

ENGINE CONTROL SYSTEM
EC-33
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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 1 can then better reduce CO, HC and NOx emissions. This system uses heated oxy-
gen 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-205
. 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 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 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

EC-34
[VQ35DE]
ENGINE CONTROL SYSTEM
Revision: 2004 November 2004 FX35/FX45
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 six cylinders twice each engine cycle. In other words, pulse signals of
the same width are simultaneously transmitted from the ECM.
The six 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 or operation of the engine at excessively high speeds.
Electronic Ignition (EI) SystemABS006K8
INPUT/OUTPUT SIGNAL CHART
*1: This signal is sent to the ECM through CAN communication line.
*2: ECM determines the start signal status by the signals of engine speed and battery voltage.
SYSTEM DESCRIPTION
The ignition timing is controlled by the ECM to maintain the best air-
fuel ratio for every running condition of the engine. The ignition tim-
ing data is stored in the ECM. This data forms the map shown.
The ECM receives information such as the injection pulse width and
camshaft position sensor signal. Computing this information, ignition
signals are transmitted to the power transistor.
e.g., N: 1,800 rpm, Tp: 1.50 msec
A °BTDC
During the following conditions, the ignition timing is revised by the
ECM according to the other data stored in the ECM.

At starting

During warm-up
SEF179U
Sensor Input Signal to ECM ECM function Actuator
Crankshaft position sensor (POS)
Engine speed*
2
Piston position
Ignition timing
controlPower transistor Camshaft position sensor (PHASE)
Mass air flow sensor Amount of intake air
Engine coolant temperature sensor Engine coolant temperature
Throttle position sensor Throttle position
Accelerator pedal position sensor Accelerator pedal position
Knock sensor Engine knocking
Park/neutral position (PNP) switch Gear position
Battery
Battery voltage*
2
Wheel sensor*1Vehicle speed
SEF742M