ENGINE CONTROL SYSTEM
EC-25
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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
EC-26
[QG (WITH EURO-OBD)]
ENGINE CONTROL SYSTEM
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
●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.
Air Conditioning Cut ControlEBS00K37
INPUT/OUTPUT SIGNAL CHART
*1: These signals are 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
This system improves engine operation when the air conditioner is used.
Under the following conditions, the air conditioner is turned off.
●When the accelerator pedal is fully depressed.
●When cranking the engine.
●At high engine speeds.
●When the engine coolant temperature becomes excessively high.
●When operating power steering during low engine speed or low vehicle speed.
●When engine speed is excessively low.
●When refrigerant pressure is excessively low or high.
SEF742M
Sensor Input Signal to ECM ECM Function Actuator
Air conditioner switch*
1Air conditioner “ON” signal
Air conditioner
cut controlAir conditioner relay Throttle position sensor Throttle valve opening angle
Crankshaft position sensor (POS)
Camshaft position sensor (PHASE)Engine speed
*2
Engine coolant temperature sensor Engine coolant temperature
Battery
Battery voltage
*2
Refrigerant pressure sensor Refrigerant pressure
Power steering pressure sensor Power steering operation
Vehicle speed signal
*1Vehicle speed
EC-32
[QG (WITH EURO-OBD)]
BASIC SERVICE PROCEDURE
PREPARATION
Before performing “Idle Air Volume Learning”, make sure that all of the following conditions are satisfied.
Learning will be cancelled if any of the following conditions are missed for even a moment.
●Battery voltage: More than 12.9V (At idle)
●Engine coolant temperature: 70 - 95°C (158 - 203°F)
●PNP switch: ON
●Electric load switch: OFF
(Air conditioner, headlamp, rear window defogger)
On vehicles equipped with daytime light systems, set lighting switch to the 1st position to light
only small lamps.
●Steering wheel: Neutral (Straight-ahead position)
●Vehicle speed: Stopped
●Transmission: Warmed-up
For A/T models with CONSULT-II, drive vehicle until “FLUID TEMP SE” in “DATA MONITOR” mode of “A/
T” system indicates less than 0.9V.
For A/T models without CONSULT-II and M/T models, drive vehicle for 10 minutes.
OPERATION PROCEDURE
With CONSULT-II
1. Perform EC-31, "Accelerator Pedal Released Position Learning" .
2. Perform EC-31, "
Throttle Valve Closed Position Learning" .
3. Start engine and warm it up to normal operating temperature.
4. Check that all items listed under the topic “PREPARATION” (previously mentioned) are in good order.
5. Select “IDLE AIR VOL LEARN” in “WORK SUPPORT” mode.
6. Touch “START” and wait 20 seconds.
SEF217Z
SEF454Y
ON BOARD DIAGNOSTIC (OBD) SYSTEM
EC-49
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2. Perform “SELF-DIAGNOSTIC PROCEDURE (Without CONSULT-II)” in AT section titled “TROUBLE
DIAGNOSIS”, “Self-diagnosis”. (The engine warm-up step can be skipped when performing the diagnosis
only to erase the DTC.)
3. Select Mode 4 with GST (Generic Scan Tool).
How to Erase DTC ( No Tools)
1. If the ignition switch stays “ON” after repair work, be sure to turn ignition switch OFF” once.
2. Wait at least 10 seconds and then turn it “ON” (engine stopped) again.
3. Change the diagnostic test mode from Mode II to Mode I by depressing the accelerator pedal. Refer to
EC-51, "
HOW TO SWITCH DIAGNOSTIC TEST MODE" .
●If the battery is disconnected, the emission-related diagnostic information will be lost after
approx. 24 hours.
●The following data are cleared when the ECM memory is erased.
–Diagnostic trouble codes
–1st trip diagnostic trouble codes
–Freeze frame data
–1st trip freeze frame data
–System readiness test (SRT) codes
–Test values
–Others
Actual work procedures are explained using a DTC as an example. Be careful so that not only the DTC, but all
of the data listed above, are cleared from the ECM memory during work procedures.
NATS (Nissan Anti-theft System)EBS00K3I
●If the security indicator lights up with the ignition switch in
the “ON” position or “NATS MALFUNCTION” is displayed
on “SELF-DIAG RESULTS” screen, perform self-diagnostic
results mode with CONSULT-II using NATS program card.
Refer to EL-386.
●Confirm no self-diagnostic results of NATS is displayed
before touching “ERASE” in “SELF-DIAG RESULTS” mode
with CONSULT-II.
●When replacing ECM, initialization of NATS system and reg-
istration of all NATS ignition key IDs must be carried out
with CONSULT-II using NATS program card.
Therefore, be sure to receive all keys from vehicle owner.
Regarding the procedures of NATS initialization and NATS ignition key ID registration, refer to
CONSULT-II operation manual, NATS.
Malfunction Indicator (MI)EBS00K3J
DESCRIPTION
The MI is located on the instrument panel.
1. The MI will light up when the ignition switch is turned ON without
the engine running. This is a bulb check.
●If the MI does not light up, refer to EL-129, or see EC-397 .
2. When the engine is started, the MI should go off.
If the MI remains on, the on board diagnostic system has
detected an engine system malfunction.
ON BOARD DIAGNOSTIC SYSTEM FUNCTION
The on board diagnostic system has the following four functions.
SEF515Y
SAT652J
EC-52
[QG (WITH EURO-OBD)]
ON BOARD DIAGNOSTIC (OBD) SYSTEM
codes can be identified by using the CONSULT-II or GST. A DTC will be used as an example for how to read a
code.
A particular trouble code can be identified by the number of four-digit numeral flashes. The “zero” is indicated
by the number of ten flashes. The length of time the 1,000th-digit numeral flashes on and off is 1.2 seconds
consisting of an ON (0.6-second) - OFF (0.6-second) cycle.
The 100th-digit numeral and lower digit numerals consist of a 0.3-second ON and 0.3-second OFF cycle.
A change from one digit numeral to another occurs at an interval of 1.0-second OFF. In other words, the later
numeral appears on the display 1.3 seconds after the former numeral has disappeared.
A change from one trouble code to another occurs at an interval of 1.8-second OFF.
In this way, all the detected malfunctions are classified by their DTC numbers. The DTC “0000” refers to no
malfunction. (See EC-10, "
INDEX FOR DTC" )
How to Erase Diagnostic Test Mode II (Self-diagnostic Results)
The DTC can be erased from the back up memory in the ECM by depressing accelerator pedal. Refer to EC-
51, "HOW TO SWITCH DIAGNOSTIC TEST MODE" .
●If the battery is disconnected, the DTC will be lost from the backup memory after approx 24 hours.
●Be careful not to erase the stored memory before starting trouble diagnoses.
DIAGNOSTIC TEST MODE II — HEATED OXYGEN SENSOR 1 MONITOR
In this mode, the MI displays the condition of the fuel mixture (lean or rich) which is monitored by the heated
oxygen sensor 1.
*: Maintains conditions just before switching to open loop.
To check the heated oxygen sensor 1 function, start engine in the Diagnostic Test Mode II and warm it up until
engine coolant temperature indicator points to the middle of the gauge.
Next run engine at about 2,000 rpm for about 2 minutes under no-load conditions. Then make sure that the MI
comes ON more than 5 times within 10 seconds with engine running at 2,000 rpm under no-load.
OBD System Operation ChartEBS00K3K
RELATIONSHIP BETWEEN MI, 1ST TRIP DTC, DTC, AND DETECTABLE ITEMS
●When a malfunction is detected for the first time, the 1st trip DTC and the 1st trip freeze frame data are
stored in the ECM memory.
●When the same malfunction is detected in two consecutive trips, the DTC and the freeze frame data are
stored in the ECM memory, and the MI will come on. For details, refer to EC-36, "
Two Trip Detection
Logic" .
SEF952W
MI Fuel mixture condition in the exhaust gas Air fuel ratio feedback control condition
ON Lean
Closed loop system
OFF Rich
*Remains ON or OFF Any condition Open loop system
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
TROUBLE DIAGNOSIS
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1 - 6: The numbers refer to the order of inspection.
(continued on next page)
SYSTEM — ENGINE MECHANICAL & OTHER
Power steering pressure sensor circuit 2 3 3 3 3EC-260
ECM 22333333333EC-265,
EC-268
Intake valve timing control solenoid valve cir-
cuit332 13223 3EC-272
PNP switch circuit 3 33333 3EC-356
Refrigerant pressure sensor circuit 2 3 3 3 3 4EC-387
Electrical load signal circuit 3 3 3 3EC-392
Air conditioner circuit223333333 3 2AT C - 2 9
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
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
5FE-4
Fuel piping 5 5 5 5 5 5 FE-4
Vapor lock—
Valve deposit
555555 5—
Poor fuel (Heavy weight gaso-
line, Low octane)—
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