2003 NISSAN ALMERA N16 mass air flow sensor

EC-24
[QG (WITH EURO-OBD)]
ENGINE CONTROL SYSTEM
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), the 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” (A/T models)
●High-load, high-speed operation

●During deceleration
●During high engine speed operation
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 if 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-155
. 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” (A/T models)
●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-
PBIB0121E

ENGINE CONTROL SYSTEM
EC-25
[QG (WITH EURO-OBD)]
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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.
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 four cylinders twice each engine cycle. In other words, pulse signals of
the same width are simultaneously transmitted from the ECM.
The four 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) SystemEBS00K36
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.
SEF337W
Sensor Input Signal to ECM ECM Function Actuator
Crankshaft position sensor (POS)
Camshaft position sensor (PHASE)Engine speed
*2 and piston position
Ignition timing control Power transistor 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
Vehicle speed signal*1Vehicle speed

TROUBLE DIAGNOSIS
EC-63
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Fail-safe ChartEBS00K3N
●When the DTC listed below is detected, the ECM enters fail-safe mode and the MI lights up.
Priority Detected items (DTC)
1
●U1000 U1001 CAN communication line
●P0102 P0103 Mass air flow sensor
●P0112 P0113 Intake air temperature sensor
●P0117 P0118 Engine coolant temperature sensor
●P0221 P0222 P0223 P1223 P1224 P1225 P1226 P1229 Throttle position sensor
●P0226 P0227 P0228 P1227 P1228 Accelerator pedal position sensor
●P0327 P0328 Knock sensor
●P0335 Crankshaft position sensor (POS)
●P0340 Camshaft position sensor (PHASE)
●P0500 Vehicle speed sensor
●P0705 Park/Neutral position (PNP) switch
●P0605 ECM
●P1610-P1615 NATS
●P1706 Park/Neutral position (PNP) switch
2
●P0031 P0032 Heated oxygen sensor 1 heater
●P0037 P0038 Heated oxygen sensor 2 heater
●P0132 P0133 P0134 P1143 P1144 Heated oxygen sensor 1
●P0138 P0139 P1146 P1147 Heated oxygen sensor 2
●P0550 Power steering pressure sensor
●P0710-P0725 P0740-P0755 P1705 P1760 A/T related sensors and solenoid valves
●P1065 ECM power supply
●P 1111 I n ta k e v a l v e t i m i n g c o n t r o l s o l e n o i d v a l v e
●P1122 Electric throttle control function
●P1124 P1126 P1128 Electric throttle control actuator
●P1805 Brake switch
3
●P0011 Intake valve timing control
●P0171 P0172 Fuel injection system function
●P0300 - P0304 Misfire
●P0420 Three way catalyst function
●P0444 EVAP canister purge volume control solenoid valve
●P0731-P0734 A/T function
●P1121 Electric throttle control actuator
●P1217 Engine over temperature (OVERHEAT)
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.

EC-70
[QG (WITH EURO-OBD)]
TROUBLE DIAGNOSIS
Symptom Matrix Chart
EBS00K3P
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-381
Fuel pressure regulator system334444444 4EC-34
Injector circuit 11232 22 2EC-375
Evaporative emission system 334444444 4EC-251,
EC-399
Air Positive crankcase ventilation sys-
tem334444444 41EC-402
Incorrect idle speed adjustment 33 1111 1EC-65
Electric throttle control actuator 112332222 2 2EC-276
,
EC-278
,
EC-285
,
EC-291
IgnitionIncorrect ignition timing adjustment33111 11 1EC-65
Ignition circuit 11222 22 2EC-365
Main power supply and ground circuit 22333 33 23EC-110
Mass air flow sensor circuit 11222 22 2EC-134
Engine coolant temperature sensor circuit 11222322312EC-144
Throttle position sensor circuit 12 22222 2EC-199
,
EC-205
,
EC-335
,
EC-341
,
EC-343
,
EC-352
Accelerator pedal position sensor circuit3212 2EC-211
,
EC-218
,
EC-345
Heated oxygen sensor 1 circuit 1232 22 2EC-149
,
EC-155
,
EC-165
,
EC-296
,
EC-302
Knock sensor circuit 2 2 3EC-230
Crankshaft position sensor (POS) circuit 2 2EC-234
Camshaft position sensor (PHASE) circuit 2 2EC-240
Vehicle speed signal circuit 2 3 3 3EC-257

EC-72
[QG (WITH EURO-OBD)]
TROUBLE DIAGNOSIS
Air Air duct
55555 5EM-14
Air cleanerEM-14
Air leakage from air duct
(Mass air flow sensor —electric
throttle control actuator)
5555EM-14
Electric throttle control actuatorEM-16
Air leakage from intake manifold/
Collector/GasketEM-16
Cranking Battery
111111 11SC-3
Alternator circuitSC-27
Starter circuit 3 SC-13
Signal plate/Flywheel/Drive plate 6EM-70
PNP switch
4AT- 11 6,
MT-21
Engine Cylinder head
55555 55 5EM-57
Cylinder head gasket 4 3
Cylinder block
66666 66 64
EM-70
Piston
Piston ring
Connecting rod
Bearing
Crankshaft
Va l v e
mecha-
nismTimin g c hain
55555 55 5EM-47
CamshaftEM-32
Intake valve timing controlEM-47
Intake valve
3EM-57
Exhaust valve
Exhaust Exhaust manifold/Tube/Muffler/
Gasket
55555 55 5EM-19
, FE-
26
Three way catalyst
Lubrica-
tionOil pan/Oil strainer/Oil pump/Oil
filter/Oil gallery
55555 55 52EM-22
, LC-
5, LC-9,
LC-4
Oil level (Low)/Filthy oilLC-8 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-83
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22
23
41
42G/B
R/B
L/B
Y/BInjector No. 3
Injector No. 1
Injector No. 4
Injector No. 2[Engine is running]
●Warm-up condition
●Idle speedBATTERY VOLTAGE
(11 - 14V)
[Engine is running]
●Warm-up condition
●Engine speed is 2,000 rpm.BATTERY VOLTAGE
(11 - 14V)
24 GHeated oxygen sensor 1
heater[Engine is running]
●Warm-up condition
●Engine speed is below 3,200 rpm (A/T
models).
●Engine speed is below 3,600 rpm (M/T
models).Approximately 7.0V
[Ignition switch “ON”]
●Engine stopped.
[Engine is running]
●Engine speed is above 3,200 rpm (A/T
models).
●Engine speed is above 3,600 rpm (M/T
models).BATTERY VOLTAGE
(11 - 14V)
29 BCamshaft position sensor
(PHASE) ground[Engine is running]
●Idle speedApproximately 0V
30 BCrankshaft position sensor
(POS) ground[Engine is running]
●Idle speedApproximately 0V
34 BRIntake air temperature
sensor[Engine is running]Approximately 0 - 4.8V
Output voltage varies with
intake air temperature.
35 W Heated oxygen sensor 1[Engine is running]
●Warm-up condition
●Engine speed is 2,000 rpm.0 - Approximately 1.0V
(Periodically change)
45 RSensor power supply
(Mass air flow sensor)[Ignition switch “ON”]Approximately 5V
46 RSensor power supply
(Refrigerant pressure
sensor)[Ignition switch “ON”]Approximately 5V
47 GSensor power supply
(Throttle position sensor)[Ignition switch “ON”]Approximately 5V TERMI-
NAL
NO.WIRE
COLORITEM CONDITION DATA (DC Voltage)
PBIB0529E
PBIB0530E
PBIB0519E

EC-84
[QG (WITH EURO-OBD)]
TROUBLE DIAGNOSIS
49 W Throttle position sensor 1[Ignition switch “ON”]
●Engine stopped.
●Shift lever position is ″D″ (A/T models).
●Shift lever position is “1st” (M/T models).
●Accelerator pedal fully released.More than 0.36V
[Ignition switch “ON”]
●Engine stopped.
●Shift lever position is ″D″ (A/T models).
●Shift lever position is “1st” (M/T models).
●Accelerator pedal fully depressed.Less than 4.75V
50 Y Mass air flow sensor[Engine is running]
●Warm-up condition
●Idle speed1.0 - 1.7V
[Engine is running]
●Warm-up condition
●Engine speed is 2,500 rpm.1.5 - 2.1V
54 -Sensor ground
(Knock sensor shield circuit)[Engine is running]
●Idle speedApproximately 0V
57 BSensor ground
(Power steering pressure
sensor/Refrigerant pressure
sensor)[Engine is running]
●Warm-up condition
●Idle speedApproximately 0V
60
61
79
80L/R
BR
GY/R
PUIgnition signal No. 3
Ignition signal No. 1
Ignition signal No. 4
Ignition signal No. 2[Engine is running]
●Warm-up condition
●Idle speed0 - 0.1V
[Engine is running]
●Warm-up condition
●Engine speed is 2,000 rpm.0 - 0.2V TERMI-
NAL
NO.WIRE
COLORITEM CONDITION DATA (DC Voltage)
PBIB0521E
PBIB0522E

TROUBLE DIAGNOSIS
EC-85
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62 Y/RIntake valve timing control
solenoid valve[Engine is running]
●Warm-up condition
●Idle speedBATTERY VOLTAGE
(11 - 14V)
[Engine is running]
●Warm-up condition
●When revving engine up to 2,000 rpm
quickly.7 - 10V
65 GSensor power supply
(Power steering pressure
sensor)[Ignition switch “ON”]Approximately 5V
66 BSensor ground
(Throttle position sensor)[Engine is running]
●Warm-up condition
●Idle speedApproximately 0V
67 BSensor ground
(Mass air flow sensor)[Engine is running]
●Warm-up condition
●Idle speedApproximately 0V
68 R Throttle position sensor 2[Ignition switch “ON”]
●Engine stopped.
●Shift lever position is ″D″ (A/T models).
●Shift lever position is “1st” (M/T models).
●Accelerator pedal fully released.Less than 4.75V
[Ignition switch “ON”]
●Engine stopped.
●Shift lever position is ″D″ (A/T models).
●Shift lever position is “1st” (M/T models).
●Accelerator pedal fully depressed.More than 0.36V
69 L Refrigerant pressure sensor[Engine is running]
●Warm-up condition
●Both A/C switch and blower switch are
“ON”.
(Compressor operates.)1.0 - 4.0V
72 BR/WEngine coolant temperature
sensor[Engine is running]Approximately 0 - 4.8V
Output voltage varies with
engine coolant temperature.
73 BSensor ground
(Engine coolant temperature
sensor)[Engine is running]
●Warm-up condition
●Idle speedApproximately 0V
74 BSensor ground
(Heated oxygen sensor)[Engine is running]
●Warm-up condition
●Idle speedApproximately 0V TERMI-
NAL
NO.WIRE
COLORITEM CONDITION DATA (DC Voltage)
MBIB0052E
PBIB0532E