2008 INFINITI FX35 Mass air flow sensor

CO-40
< SERVICE INFORMATION >[VK45DE]
RADIATOR
RADIATOR
ComponentINFOID:0000000001325871
Removal and InstallationINFOID:0000000001325872
REMOVAL
WARNING:
Do not remove radiator cap when engine is hot.
Serious burns could occur from high-pressure engine
coolant escaping from radiator. Wrap a thick cloth arou nd radiator cap. Slowly turn it a quarter of a
turn to release built-up pressure. Carefully remove radiator cap by turning it all the way.
1. Remove engine cover with power tool. Refer to EM-169, "
Component".
2. Remove engine front undercover with power tool.
3. Drain engine coolant from radiator. Refer to CO-37, "
Changing Engine Coolant".
CAUTION:
Perform this step when engine is cold.
4. Remove air duct (inlet), air cleaner case and mass air flow sensor assembly. Refer to EM-173, "
Compo-
nent".
5. Remove radiator hoses (upper and lower). CAUTION:
Do not spill engine coolant on drive belts.
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
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EC-8
Component Inspection ...........................................545
ASCD INDICATOR ..........................................547
Component Description ....................................... ..547
CONSULT-III Reference Value in Data Monitor
Mode .................................................................... ..
547
Wiring Diagram ......................................................548
Diagnosis Procedure .............................................548
ELECTRICAL LOAD SIGNAL .........................550
Description ........................................................... ..550
CONSULT-III Reference Value in Data Monitor
Mode .................................................................... ..
550
Diagnosis Procedure .............................................550
FUEL INJECTOR .............................................552
Component Description ....................................... ..552
CONSULT-III Reference Value in Data Monitor
Mode .................................................................... ..
552
Wiring Diagram ......................................................553
Diagnosis Procedure .............................................554
Component Inspection ...........................................557
Removal and Installation .......................................557
FUEL PUMP .....................................................558
Description ........................................................... ..558
CONSULT-III Reference Value in Data Monitor
Mode .................................................................... ..
558
Wiring Diagram ......................................................559
Diagnosis Procedure .............................................560
Component Inspection ...........................................562
Removal and Installation .......................................562
ICC BRAKE SWITCH ......................................563
Component Description ....................................... ..563
CONSULT-III Reference Value in Data Monitor
Mode .................................................................... ..
563
Wiring Diagram ......................................................564
Diagnosis Procedure .............................................565
Component Inspection ...........................................567
IGNITION SIGNAL ...........................................569
Component Description ....................................... ..569
Wiring Diagram ......................................................570
Diagnosis Procedure .............................................575
Component Inspection ...........................................578
Removal and Installation .......................................580
REFRIGERANT PRESSURE SENSOR ..........581
Component Description ....................................... ..581
Wiring Diagram ......................................................582
Diagnosis Procedure .............................................583
Removal and Installation .......................................585
SNOW MODE SWITCH ...................................586
Description ........................................................... ..586
CONSULT-III Reference Value in Data Monitor
Mode .................................................................... ..
586
Wiring Diagram ......................................................587
Diagnosis Procedure .............................................587
Component Inspection ...........................................589
MIL AND DATA LINK CONNECTOR ...............591
Wiring Diagram .................................................... .591
SERVICE DATA AND SPECIFICATIONS
(SDS) ................................................................
593
Fuel Pressure ....................................................... .593
Idle Speed and Ignition Timing .............................593
Calculated Load Value ..........................................593
Mass Air Flow Sensor ...........................................593
Intake Air Temperature Sensor .............................593
Engine Coolant Temperature Sensor ...................593
Air Fuel Ratio (A/F) Sensor 1 Heater ....................593
Heated Oxygen sensor 2 Heater ..........................593
Crankshaft Position Sensor (POS) .......................594
Camshaft Position Sensor (PHASE) .....................594
Throttle Control Motor .......................................... .594
Fuel Injector ..........................................................594
Fuel Pump .............................................................594
VK45DE
SERVICE INFORMATION .. .......................
595
INDEX FOR DTC ............................................ ..595
DTC No. Index ..................................................... .595
Alphabetical Index .................................................598
PRECAUTIONS .............................................. ..603
Precaution for Supplemental Restraint System
(SRS) "AIR BAG" and "SEAT BELT PRE-TEN-
SIONER" .............................................................. .
603
Precaution for Procedure without Cowl Top Cover .603
On Board Diagnosis (OBD) System of Engine and
A/T ........................................................................
603
Precaution .............................................................604
PREPARATION ................................................607
Special Service Tool ............................................ .607
Commercial Service Tool ......................................608
ENGINE CONTROL SYSTEM ..........................609
Schematic ............................................................ .609
Multiport Fuel Injection (MFI) System ...................609
Electronic Ignition (EI) System ..............................612
Fuel Cut Control (at No Load and High Engine
Speed) ..................................................................
612
AIR CONDITIONING CUT CONTROL .............614
Input/Output Signal Chart .................................... .614
System Description ...............................................614
AUTOMATIC SPEED CONTROL DEVICE
(ASCD) ..............................................................
615
System Description .............................................. .615
Component Description ........................................616
CAN COMMUNICATION ..................................617
System Description .............................................. .617
EVAPORATIVE EMISSION SYSTEM ..............618
Description ........................................................... .618
Component Inspection ..........................................620
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EC-16
Description ...........................................................1182
CONSULT-III Reference Value in Data Monitor
Mode ....................................................................
1182
Wiring Diagram ....................................................1183
Diagnosis Procedure ...........................................1183
Component Inspection .........................................1185
VARIABLE INDUCTION AIR CONTROL SYS-
TEM (VIAS) .....................................................
1187
Description ...........................................................1187
CONSULT-III Reference Va lue in Data Monitor
Mode ....................................................................
1188
Wiring Diagram ....................................................1189
Diagnosis Procedure ...........................................1190
Component Inspection .........................................1193
Removal and Installation .....................................1193
MIL AND DATA LINK CONNECTOR .............1194
Wiring Diagram ....................................................1194
SERVICE DATA AND SPECIFICATIONS
(SDS) ..............................................................
1196
Fuel Pressure .......................................................1196
Idle Speed and Ignition Timing ............................1196
Calculated Load Value .........................................1196
Mass Air Flow Sensor ..........................................1196
Intake Air Temperature Sensor ............................1196
Engine Coolant Temperature Sensor ..................1196
Fuel Tank Temperature Sensor ...........................1196
Crankshaft Position Sensor (POS) ......................1197
Camshaft Position Sensor (PHASE) ....................1197
A/F Sensor 1 Heater ............................................1197
Heated Oxygen sensor 2 Heater .........................1197
Throttle Control Motor ..........................................1197
Fuel Injector .........................................................1197
Fuel Pump ............................................................1197
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PRECAUTIONSEC-27
< SERVICE INFORMATION > [VQ35DE]
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Before replacing ECM, perform “ECM Terminals and Refer-
ence Value” inspection and m ake sure ECM functions prop-
erly. Refer to EC-109, "
ECM Terminal and Reference Value".
 Handle mass air flow sensor carefully to avoid damage.
 Do not disassemble mass air flow sensor.
 Do not clean mass air flow senso r with any type of detergent.
 Do not disassemble electric th rottle control actuator.
 Even a slight leak in the air intake system can cause serious
incidents.
 Do not shock or jar the camsh aft position sensor (PHASE),
crankshaft position sensor (POS).
 After performing each TROUBL E DIAGNOSIS, perform DTC
Confirmation Procedure or Overall Function Check.
The DTC should not be displ ayed in the DTC Confirmation
Procedure if the repair is completed. The Overall Function
Check should be a good result if the repair is completed.
 When measuring ECM signals with a circuit tester, never allow
the two tester probes to contact.
Accidental contact of probes will cause a short circuit and
damage the ECM power transistor.
 Do not use ECM ground termina ls when measuring input/out-
put voltage. Doing so may result in damage to the ECM's tran-
sistor. Use a ground other than ECM terminals, such as the
ground.
MEF040D
SEF217U
SEF348N
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EC-32
< SERVICE INFORMATION >[VQ35DE]
ENGINE CONTROL SYSTEM
*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). 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
by input signals (for engine speed and intake air) from both the crankshaft position sensor and the mass air
flow sensor.
VARIOUS FUEL INJECTION I NCREASE/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 1 can then better reduce CO, HC and NOx emissions. This system uses air fuel ratio
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
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
PBIB3020E
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ENGINE CONTROL SYSTEMEC-33
< SERVICE INFORMATION > [VQ35DE]
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(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-220
. 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 thr ee 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 bas ic 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 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 air fuel ratio (A/F) sensor 1 i ndicates whether the mixture ratio is RICH or LEAN com-
pared to the theoretical value. The signal then triggers a r eduction 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.
FUEL INJECTION TIMING
Two types of systems are used.
Sequential Multiport Fuel Injection System
Fuel is injected into each cylinder during each engine cycl e 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 fuel 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.
SEF179U
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EC-34
< SERVICE INFORMATION >[VQ35DE]
ENGINE CONTROL SYSTEM
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.
Electronic Ignition (EI) SystemINFOID:0000000001325897
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
Firing order: 1 - 2 - 3 - 4 - 5 - 6
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.
The ECM receives information such as the injection 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 re vised 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.
Fuel Cut Control (at No Load and High Engine Speed)INFOID:0000000001325898
INPUT/OUTPUT SIGNAL CHART
*: This signal is sent to the ECM through CAN communication line.
SYSTEM DESCRIPTION
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
Vehicle speed*1
Sensor Input Signal to ECM ECM function Actuator
Park/neutral position (P NP) switch Neutral position
Fuel cut control Fuel injector
Accelerator pedal position sensor Accelerator pedal position
Engine coolant temperature sensor Engine coolant temperature
Crankshaft position sensor (POS)
Camshaft position sensor (PHASE)
Engine speed
Wheel sensor Vehicle speed*
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EC-94
< SERVICE INFORMATION >[VQ35DE]
TROUBLE DIAGNOSIS

If DTC U1000 or U1001 is displayed with other DT C, first perform the trouble diagnosis for DTC
U1000, U1001. Refer to EC-146
.
 If DTC U1010 is displayed with other DTC, fi rst perform the trouble diagnosis for DTC U1010.
Refer to EC-148
.
*: Models with ICC.Priority Detected items (DTC)
1  U1000 U1001 CAN communication line  U1010 CAN communication
 P0101 P0102 P0103 Mass air flow sensor
 P0112 P0113 P0127 Intake air temperature sensor
 P0117 P0118 P0125 Engine coolant temperature sensor
 P0128 Thermostat function
 P0122 P0123 P0222 P0223 P1225 P1226 P2135 Throttle position sensor
 P0181 P0182 P0183 Fuel tank temperature sensor
 P0327 P0328 Knock sensor
 P0335 Crankshaft position sensor (POS)
 P0340 P0345 Camshaft position sensor (PHASE)
 P0460 P0461 P0462 P0463 Fuel level sensor
 P0500 Vehicle speed sensor
 P0605 ECM
 P0643 Sensor power supply
 P0700 TCM
 P0705 Park/neutral position (PNP) switch
 P0850 Park/neutral position (PNP) switch
 P1610 - P1615 NATS
 P2122 P2123 P2127 P2128 P2138 Accelerator pedal position sensor
2  P0031 P0032 P0051 P0052 Air fuel ratio (A/F) sensor 1 heater  P0037 P0038 P0057 P0058 Heated oxygen sensor 2 heater
 P0075 P0081 Intake valve timing control solenoid valve
 P0130 P0131 P0132 P0133 P0150 P0151 P0152 P0153 P2A00 P2A03 Air fuel ratio (A/F) sensor 1
 P0137 P0138 P0139 P0157 P0158 P0159 Heated oxygen sensor 2
 P0441 EVAP control system purge flow monitoring
 P0443 P0444 P0445 EVAP canister purge volume control solenoid valve
 P0447 P0448 EVAP canister vent control valve
 P0451 P0452 P0453 EVAP control system pressure sensor
 P0550 Power steering pressure sensor
 P0603 ECM power supply
 P0710 P0717 P0720 P0731 P0732 P0733 P0734 P0735 P0740 P0744 P0745 P1730 P1752 P1757 P1762 P1767
P1772 P1774 A/T related sensors, solenoid valves and switches
 P1217 Engine over temperature (OVERHEAT)
 P1805 Brake switch
 P2100 P2103 P2118 Electric throttle control actuator
 P2101 Electric throttle control function
3  P0011 P0021 Intake valve timing control  P0171 P0172 P0174 P0175 Fuel injection system function
 P0300 - P0306 Misfire
 P0420 P0430 Three way catalyst function
 P0442 EVAP control system (SMALL LEAK)
 P0455 EVAP control system (GROSS LEAK)
 P0456 EVAP control sys tem (VERY SMALL LEAK)
 P0506 P0507 Idle speed control system
 P1148 P1168 Closed loop control
 P1211 TCS control unit
 P1212 TCS communication line
 P1421 COLD START CONTROL
 P1564 ICC steering switch/ASCD steering switch
 P1568 ICC command valve*
 P1572 ICC brake switch/ASCD brake switch
 P1574 ICC vehicle speed sensor/ASCD vehicle speed sensor
 P1715 Turbine revolution sensor
 P2119 Electric throttle control actuator
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