Mass air flow INFINITI M35 2007 Factory Manual PDF

ENGINE CONTROL SYSTEM
EC-733
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Revision: 2007 April2007 M35/M45
Multiport Fuel Injection (MFI) SystemNBS0059J
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 the crankshaft position sensor (POS), camshaft position
sensor (PHASE) and the mass air flow sensor.
VARIOUS FUEL INJECTION INCREASE/DECREASE COMPENSATION
In addition, the amount of fuel injected is compensated to improve engine performance under various operat-
ing conditions as listed below.


During warm-up

When starting the engine

During acceleration

Hot-engine operation

When selector lever is changed from N to D

High-load, high-speed operation


During deceleration

During high engine speed operation
Sensor Input Signal to ECM ECM function Actuator
Crankshaft position sensor (POS)
Engine speed*
3
Piston position
Fuel injection
& mixture ratio
controlFuel injector Camshaft position sensor (PHASE)
Mass air flow sensor Amount of intake air
Engine coolant temperature sensor Engine coolant temperature
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
Battery
Battery voltage*
3
Knock sensor Engine knocking condition
Power steering pressure sensor Power steering operation
Heated oxygen sensor 2*
1Density of oxygen in exhaust gas
ABS actuator and electric unit (control unit)
VDC/TCS operation command*
2
Air conditioner switch
Air conditioner operation*2
Wheel sensor
Vehicle speed*2

EC-734
[VK45DE]
ENGINE CONTROL SYSTEM
Revision: 2007 April2007 M35/M45
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 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 A/F sensor 1, refer to
EC-947, "
DTC P0130, P0150 A/F SENSOR 1" . This maintains the mixture ratio within the range of stoichio-
metric (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 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 A/F sensor 1 or its circuit

Insufficient activation of 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 A/F sensor 1.
This feedback signal is then sent to the ECM. The ECM controls the basic mixture ratio as close to the theoret-
ical mixture ratio as possible. However, the basic mixture ratio is not necessarily controlled as originally
designed. Both manufacturing differences (i.e., mass air flow sensor hot wire) and characteristic changes dur-
ing 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 A/F sensor 1 indicates whether the mixture ratio is RICH or LEAN compared to the the-
oretical 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

ENGINE CONTROL SYSTEM
EC-735
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Revision: 2007 April2007 M35/M45
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 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.
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) SystemNBS0059K
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 - 8 - 7 - 3 - 6 - 5 - 4 - 2
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 signals are transmitted to the power transistor.
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

At idle

At low battery voltage
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
Battery
Battery voltage*
2
Knock sensor Engine knocking
Park/neutral position (PNP) switch Gear position
Wheel sensor
Vehicle speed*
1

EC-798
[VK45DE]
TROUBLE DIAGNOSIS
Revision: 2007 April2007 M35/M45
DTC Inspection Priority ChartNBS005AF
If some DTCs are displayed at the same time, perform inspections one by one based on the following priority
chart.
NOTE:

If DTC U1000 or U1001 is displayed with other DTC, first perform the trouble diagnosis for DTC
U1000, U1001. Refer to EC-865, "
DTC U1000, U1001 CAN COMMUNICATION LINE" .

If DTC U1010 is displayed with other DTC, first perform the trouble diagnosis for DTC U1010. Refer
to EC-868, "
DTC U1010 CAN COMMUNICATION" .
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

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

P0643 Sensor power supply

P0700 TCM

P0705 Park/Neutral position (PNP) switch

P0850 Park/Neutral position (PNP) switch

P1550 P1551 P1552 P1553 P1554 Battery current sensor

P1610 - P1615 NATS

P2122 P2123 P2127 P2128 P2138 Accelerator pedal position sensor

EC-800
[VK45DE]
TROUBLE DIAGNOSIS
Revision: 2007 April2007 M35/M45
Fail-Safe ChartNBS005AG
When the DTC listed below is detected, the ECM enters fail-safe mode and the MIL lights up.

When there is an open circuit on MIL circuit, the ECM cannot warn the driver by lighting up MIL when
there is malfunction on engine control system.
Therefore, when electrical controlled throttle and part of ECM related diagnoses are continuously detected
as NG for 5 trips, ECM warns the driver that engine control system malfunctions and MIL circuit is open by
means of operating fail-safe function.
The fail-safe function also operates when above diagnoses except MIL circuit are detected and demands
the driver to repair the malfunction.
DTC No. Detected items Engine operating condition in fail-safe mode
P0102
P0103Mass air flow sensor circuit Engine speed will not rise more than 2,400 rpm due to the fuel cut.
P0117
P0118Engine coolant tempera-
ture sensor circuitEngine coolant temperature will be determined by ECM based on the time after turning
ignition switch ON or START.
CONSULT-II displays the engine coolant temperature decided by ECM.
ConditionEngine coolant temperature decided
(CONSULT-II display)
Just as ignition switch is turned
ON or START40°C (104°F)
More than approx. 4 minutes after
ignition ON or START80°C (176°F)
Except as shown above40 - 80°C (104 - 176°F)
(Depends on the time)
When the fail-safe system for engine coolant temperature sensor is activated, the cooling
fan operates while engine is running.
P0122
P0123
P0222
P0223
P2135Throttle position sensor The ECM controls the electric throttle control actuator in regulating the throttle opening in
order for the idle position to be within +10 degrees.
The ECM regulates the opening speed of the throttle valve to be slower than the normal
condition.
So, the acceleration will be poor.
P0643 Sensor power supply ECM stops the electric throttle control actuator control, throttle valve is maintained at a
fixed opening (approx. 5 degrees) by the return spring.
P2100
P2103Throttle control motor relay ECM stops the electric throttle control actuator control, throttle valve is maintained at a
fixed opening (approx. 5 degrees) by the return spring.
P2101 Electric throttle control
functionECM stops the electric throttle control actuator control, throttle valve is maintained at a
fixed opening (approx. 5 degrees) by the return spring.
P2118 Throttle control motor ECM stops the electric throttle control actuator control, throttle valve is maintained at a
fixed opening (approx. 5 degrees) by the return spring.
P2119 Electric throttle control
actuator(When electric throttle control actuator does not function properly due to the return spring
malfunction:)
ECM controls the electric throttle actuator by regulating the throttle opening around the
idle position. The engine speed will not rise more than 2,000 rpm.
(When throttle valve opening angle in fail-safe mode is not in specified range:)
ECM controls the electric throttle control actuator by regulating the throttle opening to 20
degrees or less.
(When ECM detects the throttle valve is stuck open:)
While the vehicle is driving, it slows down gradually by fuel cut. After the vehicle stops,
the engine stalls.
The engine can restart in N or P position, and engine speed will not exceed 1,000 rpm or
more.
P2122
P2123
P2127
P2128
P2138Accelerator pedal position
sensorThe ECM controls the electric throttle control actuator in regulating the throttle opening in
order for the idle position to be within +10 degrees.
The ECM regulates the opening speed of the throttle valve to be slower than the normal
condition.
So, the acceleration will be poor.
Engine operating condition in fail-safe mode Engine speed will not rise more than 2,500 rpm due to the fuel cut

TROUBLE DIAGNOSIS
EC-801
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Revision: 2007 April2007 M35/M45
Symptom Matrix ChartNBS005AH
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-1395
Fuel pressure regulator system334444444 4EC-791
Fuel injector circuit 11232 22 2EC-1389
Evaporative emission system334444444 4EC-741
Air Positive crankcase ventilation sys-
tem
334444444 41EC-753
Incorrect idle speed adjustment 1 1 1 1 1EC-780
Electric throttle control actuator 112332222 2 2EC-1322,
EC-1334
IgnitionIncorrect ignition timing adjustment33111 11 1EC-780
Ignition circuit 11222 22 2EC-1411
Main power supply and ground circuit22333 33 23EC-858
Mass air flow sensor circuit
1
122
222 2EC-906,
EC-915
Engine coolant temperature sensor circuit
333EC-926,
EC-939
Air fuel ratio (A/F) sensor 1 circuitEC-947
,
EC-957
,
EC-966
,
EC-975
,
EC-1365
Throttle position sensor circuit
22EC-932
,
EC-1054
,
EC-1233
,
EC-1235
,
EC-1350
Accelerator pedal position sensor circuit 3 2 1EC-1193
,
EC-1336
,
EC-1343
,
EC-1357
Knock sensor circuit 2 3EC-1070
Crankshaft position sensor (POS) circuit 2 2EC-1075
Camshaft position sensor (PHASE) circuit 3 2EC-1082
Vehicle speed signal circuit 2 3 3 3EC-1175
Power steering pressure sensor circuit 2 3 3EC-1181

TROUBLE DIAGNOSIS
EC-803
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Revision: 2007 April2007 M35/M45
Air Air duct
55555 5EM-177
Air cleanerEM-177
Air leakage from air duct
(Mass air flow sensor — electric
throttle control actuator)
5555EM-177
Electric throttle control actuatorEM-179
Air leakage from intake manifold/
Collector/GasketEM-179
Cranking Battery
111111
11SC-4
Generator circuitSC-20
Starter circuit 3SC-8
Signal plate 6EM-252
PNP switch 4AT- 11 3
Engine Cylinder head
55555 55 5EM-235
Cylinder head gasket 4 3
Cylinder block
66666 66 64
EM-252
Piston
Piston ring
Connecting rod
Bearing
Crankshaft
Va l v e
mecha-
nismTiming chain
55555 55 5EM-203
CamshaftEM-215
Intake valve timing controlEM-215
Intake valve
3EM-235
Exhaust valve
Exhaust Exhaust manifold/Tube/Muffler/
Gasket
55555 55 5EM-183
,
EX-3
Three way catalyst
Lubrica-
tionOil pan/Oil strainer/Oil pump/Oil
filter/Oil gallery
55555 55 5EM-187
,
LU-31
, LU-
30
Oil level (Low)/Filthy oilLU-27
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

TROUBLE DIAGNOSIS
EC-805
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Revision: 2007 April2007 M35/M45
Engine Control Component Parts LocationNBS005AI
1. IPDM E/R 2. ICC brake hold relay
(ICC models only)3. Battery current sensor
4. Cooling fan relay 5. Refrigerant pressure sensor 6. Intake valve timing control position
sensor (bank 2)
7. Vacuum tank 8. Cooling fan motor-2 9. Intake valve timing control solenoid
valve (bank 2)
10. Cooling fan control module 11. Electric throttle control actuator 12. Intake valve timing control solenoid
valve (bank 1)
13. Cooling fan motor-1 14. Intake valve timing control position
sensor (bank 1)15. Camshaft position sensor (PHASE)
16. Mass air flow sensor
(with intake air temperature sensor)17. Ignition coil (with power transistor)
and spark plug (bank 1)18. VIAS control solenoid valve
19. Fuel injector (bank 1) 20. Engine coolant temperature sensor 21. Power valve actuator
22. Knock sensor (bank 1) 23. Knock sensor (bank 2) 24. Fuel injector (bank 2)
25. EVAP canister purge volume control
solenoid valve26. EVAP service port 27. Ignition coil (with power transistor)
and spark plug (bank 2)
PBIB2674E

EC-806
[VK45DE]
TROUBLE DIAGNOSIS
Revision: 2007 April2007 M35/M45
: Vehicle front
1. Mass air flow sensor 2. Camshaft position sensor (PHASE) 3. Engine coolant temperature sensor
sub-harness connector
4. Engine coolant temperature sensor 5. Battery current sensor 6. Refrigerant pressure sensor
PBIB2675E

EC-822
[VK45DE]
TROUBLE DIAGNOSIS
Revision: 2007 April2007 M35/M45
50 W Throttle position sensor 1[Ignition switch: ON]

Engine: Stopped

Selector lever: D

Accelerator pedal: Fully releasedMore than 0.36V
[Ignition switch: ON]

Engine: Stopped

Selector lever: D

Accelerator pedal: Fully depressedLess than 4.75V
51 W Mass air flow sensor[Engine is running]

Warm-up condition

Idle speed0.9 - 1.2V
[Engine is running]

Warm-up condition

Engine speed: 2,500 rpm1.6 - 0.9V
53 LGIntake valve timing control
position sensor (bank 2)[Engine is running]

Warm-up condition

Idle speed0 - 1.0V
[Engine is running]

Engine speed: 2,000 rpm0 - 1.0V
55 L/RHeated oxygen sensor 2
(bank 1)[Engine is running]

Revving engine from idle to 3,000 rpm
quickly after the following conditions are
met.
–Engine: After warming-up
–Keeping the engine speed between 3,500
and 4,000 rpm for 1 minute and at idle for 1
minute under no load0 - Approximately 1.0V
57 BR/W
A/F sensor 1 (bank 2)[Engine is running]

Warm-up condition

Idle speedApproximately 2.6V
58 G/OApproximately 2.3V
76 G/WApproximately 3.1V
77 GRApproximately 2.3V
66 BSensor ground
(Throttle position sensor)[Engine is running]

Warm-up condition

Idle speedApproximately 0V
67 B/W Sensor ground[Engine is running]

Warm-up condition

Idle speedApproximately 0V TER-
MINAL
NO.WIRE
COLORITEM CONDITION DATA (DC Voltage)
PBIB2734E
PBIB2735E