2004 INFINITI FX35 mass air flow sensor

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

ENGINE CONTROL SYSTEM
EC-681
[VK45DE]
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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 eight cylinders twice each engine cycle. In other words, pulse signals of
the same width are simultaneously transmitted from the ECM.
The eight 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) SystemABS00BZ7
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
PBIB0122E
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

EC-682
[VK45DE]
ENGINE CONTROL SYSTEM
Revision: 2004 November 2004 FX35/FX45

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.
Nissan Torque Demand (NTD) Control SystemABS00BZ8
INPUT/OUTPUT SIGNAL CHART
*: This signal is sent to the ECM through CAN communication line.
SYSTEM DESCRIPTION
NTD control system decides the target traction based on the accelerator operation status and the current driv-
ing condition. It then selects the engine torque target by correcting running resistance and atmospheric pres-
sure, and controlling the power-train. Using electric throttle control actuator, it achieves the engine torque
development target which corresponds linearly to the driver's accelerator operation.
Running resistance correction control compares the engine torque estimate value, measured vehicle acceler-
ation, and running resistance on a flat road, and estimates vehicle weight gain and running resistance varia-
tion caused by slopes to correct the engine torque estimate value.
Atmospheric pressure correction control compares the engine torque estimate value from the airflow rate and
the target engine torque for the target traction, and estimates variation of atmospheric pressure to correct the
target engine torque. This system achieves powerful driving without reducing engine performance in the prac-
tical speed range in mountains and high-altitude areas.
Sensor Input signal to ECM ECM function Actuator
Camshaft position sensor (PHASE)
Crankshaft position sensor (POS)Engine speed
NTD controlElectric throttle con-
trol actuator and fuel
injector 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
Park/Neutral position (PNP) switch Gear position
Power steering pressure sensor Power steering operation
Battery Battery voltage
TCM (CAN communication) A/T control signal
Air conditioner switch* Air conditioner operation
ABS actuator and electric unit (control unit)* VDC/TCS/ABS operation
Wheel sensor* Vehicle speed
Electrical load* Electrical load signal

BASIC SERVICE PROCEDURE
EC-697
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Revision: 2004 November 2004 FX35/FX45
31. REPLACE HEATED OXYGEN SENSOR 1
1. Stop engine.
2. Replace heated oxygen sensor 1 on the malfunctioning bank.
With CONSULT-II>>GO TO 32.
Without CONSULT-II>>GO TO 33.
32. CHECK HEATED OXYGEN SENSOR 1 (BANK 1)/(BANK 2) SIGNAL
With CONSULT-II
1. Start engine and warm it up until engine coolant temperature indicator points the middle of gauge.
2. See “HO2S1 MNTR (B1)/(B2)” in “DATA MONITOR” mode.
3. Running engine at 2,000 rpm under no load (The engine is
warmed up to normal operating temperature.), check that the
monitor fluctuates between LEAN and RICH more than 5 times
during 10 seconds.
OK or NG
OK >> GO TO 4.
NG >> GO TO 34.
33. CHECK HEATED OXYGEN SENSOR 1 (BANK 1)/(BANK 2) SIGNAL
Without CONSULT-II
1. Set ECM to Self-diagnostic mode II (Heated oxygen sensor 1 monitor). Refer to EC-719, "
HOW TO
SWITCH DIAGNOSTIC TEST MODE" .
2. Switch the monitored sensor to the malfunctioning bank. Refer to EC-719, "
How to Switch Monitored Sen-
sor From Bank 1 to Bank 2 or Vice Versa" .
3. Running engine at 2,000 rpm under no load (The engine is warmed up to normal operating temperature.),
check that the MIL comes on more than 5 times during 10 seconds.
OK or NG
OK >> GO TO 4.
NG >> GO TO 34.
34. DETECT MALFUNCTIONING PART
Check the following.

Check fuel pressure regulator and repair or replace if necessary. Refer to EC-700, "Fuel Pressure Check"
.

Check mass air flow sensor and its circuit, and repair or replace if necessary. Refer to EC-822 , EC-830 ,
EC-1064
.

Check injector and its circuit, and repair or replace if necessary. Refer to EC-1274 .

Check engine coolant temperature sensor and its circuit, and repair or replace if necessary. Refer to EC-
842 and EC-855 .
OK or NG
OK >> GO TO 36.
NG >> 1. Repair or replace.
2. GO TO 35. 1 time: RICH → LEAN → RICH
2 times: RICH → LEAN → RICH → LEAN → RICH
PBIB0120E

EC-730
[VK45DE]
TROUBLE DIAGNOSIS
Revision: 2004 November 2004 FX35/FX45
Priority Detected items (DTC)
1

U1000 U1001 CAN communication line

P0101 P0102 P0103 P1102 Mass air flow sensor

P0112 P0113 P0127 Intake air temperature sensor

P0117 P0118 P0125 Engine coolant temperature sensor

P0122 P0123 P0222 P0223 P1225 P1226 P2135 Throttle position sensor

P0128 Thermostat function

P0181 P0182 P0183 Fuel tank temperature sensor

P0327 P0328 P0332 P0333 Knock sensor

P0335 Crankshaft position sensor (POS)

P0340 Camshaft position sensor (PHASE)

P0460 P0461 P0462 P0463 Fuel level sensor

P0500 Vehicle speed sensor

P0605 ECM

P0705 Park/Neutral position (PNP) switch

P1229 Sensor power supply

P1610 - P1615 NATS

P1706 Park/Neutral position (PNP) switch

P2122 P2123 P2127 P2128 P2138 Accelerator pedal position sensor

TROUBLE DIAGNOSIS
EC-731
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Revision: 2004 November 2004 FX35/FX45
Fail-safe ChartABS00BZQ
When the DTC listed below is detected, the ECM enters fail-safe mode and the MIL lights up.
2
P0031P0032 P0051 P0052 Heated oxygen sensor 1 heater

P0037 P0038 P0057 P0058 Heated oxygen sensor 2 heater

P0132 P0133 P0134 P0152 P0153 P0154 P1143 P1144 P1163 P1164 Heated oxygen sensor 1

P0138 P0139 P0158 P0159 P1146 P1147 P1166 P1167 Heated oxygen sensor 2

P0441 EVAP control system purge flow monitoring

P0444 P0445 P1444 EVAP canister purge volume control solenoid valve

P0447 P1446 EVAP canister vent control valve

P0451 P0452 P0453 EVAP control system pressure sensor

P0550 Power steering pressure sensor

P0710 P0720 P0740 P0744 P0745 P1716 P1720 P1730 P1752 P1754 P1757 P1759 P1762 P1764 P1767 P1769
P1772 P1774 A/T related sensors, solenoid valves and switches

P1065 ECM power supply

P 1111 P 1136 Intake valve timing control solenoid valve

P1122 Electric throttle control function

P1124 P1126 P1128 Electric throttle control actuator

P1140 P1145 Intake valve timing control position sensor

P1217 Engine over temperature (OVERHEAT)

P1805 Brake switch
3

P0011 P0021 Intake valve timing control

P0171 P0172 P0174 P0175 Fuel injection system function

P0300 - P0308 Misfire

P0420 P0430 Three way catalyst function

P0442 P0456 EVAP control system (SMALL LEAK, VERY SMALL LEAK)

P0455 EVAP control system (GROSS LEAK)

P0506 P0507 Idle speed control system

P1121 Electric throttle control actuator

P1148 P1168 Closed loop control

P1211 TCS control unit

P1212 TCS communication line

P1564 ICC steering switch/ASCD steering switch

P1568 ICC command value

P1572 ICC brake switch/ASCD brake switch

P1574 ICC vehicle speed sensor/ASCD vehicle speed sensor

P1780 Shift change signal Priority Detected items (DTC)
DTC No. Detected items Engine operating condition in fail-safe mode
P0102
P0103
P1102Mass air flow sensor circuit Engine speed will not rise more than 2,400 rpm due to the fuel cut.

EC-738
[VK45DE]
TROUBLE DIAGNOSIS
Revision: 2004 November 2004 FX35/FX45
Symptom Matrix ChartABS00BZS
SYSTEM — BASIC ENGINE CONTROL SYSTEM
SYMPTOM
Reference
page
HARD/NO START/RESTART (EXCP. HA)
ENGINE STALL
HESITATION/SURGING/FLAT SPOT
SPARK KNOCK/DETONATION
LACK OF POWER/POOR ACCELERATION
HIGH IDLE/LOW IDLE
ROUGH IDLE/HUNTING
IDLING VIBRATION
SLOW/NO RETURN TO IDLE
OVERHEATS/WATER TEMPERATURE HIGH
EXCESSIVE FUEL CONSUMPTION
EXCESSIVE OIL CONSUMPTION
BATTERY DEAD (UNDER CHARGE)
Warranty symptom code AA AB AC AD AE AF AG AH AJ AK AL AM HA
Fuel Fuel pump circuit 11232 22 3 2EC-1280
Fuel pressure regulator system334444444 4EC-700
Injector circuit 11232 22 2EC-1274
Evaporative emission system 334444444 4EC-1320
Air Positive crankcase ventilation sys-
tem
334444444 41EC-1332
Incorrect idle speed adjustment 1 1 1 1 1EC-687
Electric throttle control actuator 112332222 2 2EC-1077,
EC-1079
IgnitionIncorrect ignition timing adjustment33111 11 1EC-687
Ignition circuit 11222 22 2EC-1262
Power supply and ground circuit22333 33 23EC-785
Mass air flow sensor circuit
1
122
222 2EC-822
,
EC-830
,
EC-1064
Engine coolant temperature sensor circuit
333EC-842,
EC-855
Heated oxygen sensor 1 circuitEC-863
,
EC-872
,
EC-884
,
EC-1103
,
EC-1109
Throttle position sensor circuit
22EC-848
,
EC-942
,
EC-1152
,
EC-1154
,
EC-1156
,
EC-1239
Accelerator pedal position sensor circuit 3 2 1EC-1225
,
EC-1232
,
EC-1246
Knock sensor circuit 2 3EC-955
Crankshaft position sensor (POS) circuit 2 2EC-960
Camshaft position sensor (PHASE) circuit 3 2EC-966
Vehicle speed signal circuit 2 3 3 3EC-1046

EC-740
[VK45DE]
TROUBLE DIAGNOSIS
Revision: 2004 November 2004 FX35/FX45
SYSTEM — ENGINE MECHANICAL & OTHER
SYMPTOM
Reference
page
HARD/NO START/RESTART (EXCP. HA)
ENGINE STALL
HESITATION/SURGING/FLAT SPOT
SPARK KNOCK/DETONATION
LACK OF POWER/POOR ACCELERATION
HIGH IDLE/LOW IDLE
ROUGH IDLE/HUNTING
IDLING VIBRATION
SLOW/NO RETURN TO IDLE
OVERHEATS/WATER TEMPERATURE HIGH
EXCESSIVE FUEL CONSUMPTION
EXCESSIVE OIL CONSUMPTION
BATTERY DEAD (UNDER CHARGE)
Warranty symptom code AA AB AC AD AE AF AG AH AJ AK AL AM HA
Fuel Fuel tank
5
5FL-10
Fuel piping 5 5 5 5 5 5EM-188
Vapor lock—
Valve deposit
5 555 55 5—
Poor fuel (Heavy weight gaso-
line, Low octane)—
Air Air duct
55555 5EM-172
Air cleanerEM-172
Air leakage from air duct
(Mass air flow sensor — electric
throttle control actuator)
5555EM-172
Electric throttle control actuatorEM-174
Air leakage from intake manifold/
Collector/GasketEM-174
Cranking Battery
111111
11SC-4
Generator circuitSC-23
Starter circuit 3SC-10
Signal plate 6EM-240
PNP switch 4AT- 11 2
Engine Cylinder head
55555 55 5EM-224
Cylinder head gasket 4 3
Cylinder block
66666 66 64
EM-240
Piston
Piston ring
Connecting rod
Bearing
Crankshaft
Va l v e
mecha-
nismTiming chain
55555 55 5EM-196
CamshaftEM-208
Intake valve timing controlEM-196
Intake valve
3EM-196
Exhaust valve