2001 NISSAN X-TRAIL OBD port

TERMINOLOGY
GI-47
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GI
Nonvolatile random access memory NVRAM ***
On board diagnostic system OBD system Self-diagnosis
Open loop OL Open loop
Oxidation catalyst OC Catalyst
Oxidation catalytic converter system OC system ***
Oxygen sensor O2S Exhaust gas sensor
Park position switch *** Park switch
Park/neutral position switch PNP switchPark/neutral switch
Inhibitor switch
Neutral position switch
Periodic trap oxidizer system PTOX system ***
Positive crankcase ventilation PCV Positive crankcase ventilation
Positive crankcase ventilation valve PCV valve PCV valve
Powertrain control module PCM ***
Programmable read only memory PROM ***
Pulsed secondary air injection control sole-
noid valvePAIRC solenoid valve AIV control solenoid valve
Pulsed secondary air injection system PAIR system Air induction valve (AIV) control
Pulsed secondary air injection valve PAIR valve Air induction valve
Random access memory RAM ***
Read only memory ROM ***
Scan tool ST ***
Secondary air injection pump AIR pump ***
Secondary air injection system AIR system ***
Sequential multiport fuel injection system SFI system Sequential fuel injection
Service reminder indicator SRI ***
Simultaneous multiport fuel injection sys-
tem*** Simultaneous fuel injection
Smoke puff limiter system SPL system ***
Supercharger SC ***
Supercharger bypass SCB ***
System readiness test SRT ***
Thermal vacuum valve TVV Thermal vacuum valve
Three way catalyst TWC Catalyst
Three way catalytic converter system TWC system ***
Three way + oxidation catalyst TWC + OC Catalyst
Three way + oxidation catalytic converter
systemTWC + OC system ***
Throttle body TBThrottle chamber
SPI body
Throttle body fuel injection system TBI system Fuel injection control
Throttle position TP Throttle position
Throttle position sensor TPS Throttle sensor
Throttle position switch TP switch Throttle switch
Torque converter clutch solenoid valve TCC solenoid valveLock-up cancel solenoid
Lock-up solenoid NEW TERMNEW ACRONYM /
ABBREVIATIONOLD TERM

INTAKE MANIFOLD
EM-17
[QR]
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QR25DE
REMOVAL
WARNING:
To avoid the danger of being scalded, never drain the coolant when the engine is hot.
1. Disconnect mass air flow sensor harness connector from mass air flow sensor and clamp.
2. Release fuel pressure. Refer to EC-775, "
FUEL PRESSURE RELEASE" [QR20DE (WITH EURO-OBD)],
EC-1139, "
FUEL PRESSURE RELEASE" [QR20DE (WITHOUT EURO-OBD)], EC-42, "FUEL PRES-
SURE RELEASE" [QR25DE (WITH EURO-OBD)] or EC-452, "FUEL PRESSURE RELEASE" [QR25DE
(WITHOUT EURO-OBD)].
3. Remove air cleaner case and air duct assembly. Refer to EM-14, "
AIR CLEANER AND AIR DUCT" .
4. Drain coolant when engine is cooled. Refer to CO-9, "
DRAINING ENGINE COOLANT" .
SBIA0229E
1. Bracket 2. PCV hose 3. Intake manifold collector
4. Gasket 5. Electric throttle control actuator 6. Intake manifold support
7.EVAP canister purge volume control
solenoid valve8. Vacuum hose 9. Intake manifold
10. Vacuum reservoir tank 11. VIAS control solenoid valve

EC-1
ENGINE CONTROL SYSTEM
B ENGINE
CONTENTS
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SECTION
A
EC
ENGINE CONTROL SYSTEM
QR25(WITH EURO-OBD)
INDEX FOR DTC ...................................................... 20
Alphabetical Index .................................................. 20
DTC No. Index ....................................................... 22
PRECAUTIONS ........................................................ 25
Precautions for Supplemental Restraint System
(SRS) “AIR BAG” and “SEAT BELT PRE-TEN-
SIONER” ................................................................ 25
On Board Diagnostic (OBD) System of Engine and
A/T .......................................................................... 25
Precaution .............................................................. 25
Wiring Diagrams and Trouble Diagnosis ................ 28
PREPARATION ......................................................... 29
Special Service Tools ............................................. 29
Commercial Service Tools ...................................... 29
ENGINE CONTROL SYSTEM .................................. 31
System Diagram ..................................................... 31
Vacuum Hose Drawing ........................................... 32
System Chart ......................................................... 33
Multiport Fuel Injection (MFI) System .................... 33
Electronic Ignition (EI) System ............................... 35
Air Conditioning Cut Control ................................... 36
Fuel Cut Control (at No Load and High Engine
Speed) .................................................................... 37
CAN Communication .............................................. 37
BASIC SERVICE PROCEDURE .............................. 38
Idle Speed and Ignition Timing Check .................... 38
Accelerator Pedal Released Position Learning ...... 39
Throttle Valve Closed Position Learning ................ 39
Idle Air Volume Learning ........................................ 39
Fuel Pressure Check .............................................. 42
ON BOARD DIAGNOSTIC (OBD) SYSTEM ............ 44
Introduction ............................................................ 44
Two Trip Detection Logic ........................................ 44
Emission-related Diagnostic Information ................ 45
NATS (Nissan Anti-theft System) ........................... 58
Malfunction Indicator (MI) ....................................... 58
OBD System Operation Chart ................................ 61
TROUBLE DIAGNOSIS ............................................ 67
Trouble Diagnosis Introduction ............................... 67DTC Inspection Priority Chart ................................. 70
Fail-safe Chart ........................................................ 71
Basic Inspection ..................................................... 73
Symptom Matrix Chart ............................................ 77
Engine Control Component Parts Location ............ 81
Circuit Diagram ....................................................... 85
ECM Harness Connector Terminal Layout ............. 87
ECM Terminals and Reference Value ..................
... 87
CONSULT-II Function ............................................. 94
Generic Scan Tool (GST) Function .......................104
CONSULT-II Reference Value in Data Monitor .....106
Major Sensor Reference Graph in Data Monitor
Mode .....................................................................109
TROUBLE DIAGNOSIS - SPECIFICATION VALUE ..111
Description .............................................................111
Testing Condition ...................................................111
Inspection Procedure .............................................111
Diagnostic Procedure ...........................................112
TROUBLE DIAGNOSIS FOR INTERMITTENT INCI-
DENT .......................................................................115
Description ............................................................115
Diagnostic Procedure ...........................................115
POWER SUPPLY CIRCUIT FOR ECM ...................116
Wiring Diagram .....................................................116
ECM Terminals and Reference Value ...................117
Diagnostic Procedure ...........................................117
Component Inspection ..........................................121
DTC U1000 CAN COMMUNICATION LINE ............122
Description ............................................................122
On Board Diagnosis Logic ....................................122
DTC Confirmation Procedure ...............................122
Wiring Diagram .....................................................123
Diagnostic Procedure ...........................................124
DTC P0011 IVT CONTROL .....................................125
Description ............................................................125
CONSULT-II Reference Value in Data Monitor Mode
.125
ECM Terminals and Reference Value ...................125
On Board Diagnosis Logic ....................................126

EC-6
DATA LINK CONNECTOR ......................................424
Wiring Diagram .....................................................424
EVAPORATIVE EMISSION SYSTEM .....................425
Description ............................................................425
Component Inspection ..........................................427
POSITIVE CRANKCASE VENTILATION ...............428
Description ............................................................428
Component Inspection ..........................................428
SERVICE DATA AND SPECIFICATIONS (SDS) ....430
Fuel Pressure .......................................................430
Idle Speed and Ignition Timing .............................430
Calculated Load Value ..........................................430
Mass Air Flow Sensor ...........................................430
Intake Air Temperature Sensor .............................430
Engine Coolant Temperature Sensor ...................430
Heated Oxygen Sensor 1 Heater .........................430
Heated Oxygen sensor 2 Heater ..........................430
Crankshaft Position Sensor (POS) .......................430
Camshaft Position Sensor (PHASE) ....................431
Throttle Control Motor ...........................................431
Injector ..................................................................431
Fuel Pump ............................................................431
QR25(WITHOUT EURO-OBD)
INDEX FOR DTC .....................................................432
Alphabetical Index ................................................432
DTC No. Index ......................................................433
PRECAUTIONS .......................................................435
Precautions for Supplemental Restraint System
(SRS) “AIR BAG” and “SEAT BELT PRE-TEN-
SIONER” ...............................................................435
On Board Diagnostic (OBD) System of Engine and
A/T ........................................................................435
Precaution ............................................................435
Wiring Diagrams and Trouble Diagnosis ..............438
PREPARATION .......................................................439
Special Service Tools ...........................................439
Commercial Service Tools ....................................439
ENGINE CONTROL SYSTEM ................................441
System Diagram ...................................................441
Vacuum Hose Drawing .........................................442
System Chart ........................................................443
Multiport Fuel Injection (MFI) System ...................443
Electronic Ignition (EI) System .............................445
Air Conditioning Cut Control .................................446
Fuel Cut Control (at No Load and High Engine
Speed) ..................................................................447
CAN Communication ............................................447
BASIC SERVICE PROCEDURE .............................448
Idle Speed and Ignition Timing Check ..................448
Accelerator Pedal Released Position Learning ....449
Throttle Valve Closed Position Learning ...............449
Idle Air Volume Learning ......................................450
Fuel Pressure Check ............................................452
ON BOARD DIAGNOSTIC (OBD) SYSTEM ..........454
Introduction ...........................................................454
Two Trip Detection Logic ......................................454
Emission-related Diagnostic Information ..............454NATS (Nissan Anti-theft System) ..........................456
Malfunction Indicator (MI) .....................................457
TROUBLE DIAGNOSIS ..........................................460
Trouble Diagnosis Introduction .............................460
DTC Inspection Priority Chart ...............................463
Fail-safe Chart ......................................................464
Basic Inspection ....................................................465
Symptom Matrix Chart ..........................................469
Engine Control Component Parts Location ...........473
Circuit Diagram .....................................................477
ECM Harness Connector Terminal Layout ............479
ECM Terminals and Reference Value ...................479
CONSULT-II Function ...........................................486
CONSULT-II Reference Value in Data Monitor .....496
Major Sensor Reference Graph in Data Monitor
Mode .....................................................................499
TROUBLE DIAGNOSIS - SPECIFICATION VALUE .502
Description ............................................................502
Testing Condition ..................................................502
Inspection Procedure ........................................... .502
Diagnostic Procedure ............................................503
TROUBLE DIAGNOSIS FOR INTERMITTENT INCI-
DENT .......................................................................506
Description ............................................................506
Diagnostic Procedure ............................................506
POWER SUPPLY CIRCUIT FOR ECM ...................507
Wiring Diagram .....................................................507
ECM Terminals and Reference Value ...................508
Diagnostic Procedure ............................................508
Component Inspection ..........................................512
DTC U1000 CAN COMMUNICATION LINE ............513
Description ............................................................513
On Board Diagnosis Logic ....................................513
DTC Confirmation Procedure ................................513
Wiring Diagram .....................................................514
Diagnostic Procedure ............................................515
DTC P0102, P0103 MAF SENSOR .........................516
Component Description ........................................516
CONSULT-II Reference Value in Data Monitor Mode
.516
ECM Terminals and Reference Value ...................516
On Board Diagnosis Logic ....................................516
DTC Confirmation Procedure ................................517
Wiring Diagram .....................................................519
Diagnostic Procedure ............................................520
Component Inspection ..........................................522
Removal and Installation .......................................522
DTC P0117, P0118 ECT SENSOR ..........................523
Component Description ........................................523
On Board Diagnosis Logic ....................................523
DTC Confirmation Procedure ................................524
Wiring Diagram .....................................................525
Diagnostic Procedure ............................................526
Component Inspection ..........................................527
Removal and Installation .......................................527
DTC P0122, P0123 TP SENSOR ............................528
Component Description ........................................528
CONSULT-II Reference Value in Data Monitor Mode
.528

EC-10
Injector ..................................................................752
Fuel Pump ............................................................752
QR20(WITH EURO-OBD)
INDEX FOR DTC .....................................................753
Alphabetical Index ................................................753
DTC No. Index ......................................................755
PRECAUTIONS .......................................................757
Precautions for Supplemental Restraint System
(SRS) “AIR BAG” and “SEAT BELT PRE-TEN-
SIONER” ...............................................................757
On Board Diagnostic (OBD) System of Engine and
A/T ........................................................................757
Precaution ............................................................757
Wiring Diagrams and Trouble Diagnosis ..............760
PREPARATION .......................................................761
Special Service Tools ...........................................761
Commercial Service Tools ....................................761
ENGINE CONTROL SYSTEM ................................763
System Diagram ...................................................763
Vacuum Hose Drawing .........................................764
System Chart ........................................................765
Multiport Fuel Injection (MFI) System ...................765
Electronic Ignition (EI) System .............................768
Air Conditioning Cut Control .................................768
Fuel Cut Control (at No Load and High Engine
Speed) ..................................................................769
CAN Communication ............................................769
BASIC SERVICE PROCEDURE .............................771
Idle Speed and Ignition Timing Check ..................771
Accelerator Pedal Released Position Learning ....772
Throttle Valve Closed Position Learning ...............772
Idle Air Volume Learning ......................................772
Fuel Pressure Check ............................................775
ON BOARD DIAGNOSTIC (OBD) SYSTEM ..........777
Introduction ...........................................................777
Two Trip Detection Logic ......................................777
Emission-related Diagnostic Information ..............778
NATS (Nissan Anti-theft System) ..........................790
Malfunction Indicator (MI) .....................................790
OBD System Operation Chart ..............................793
TROUBLE DIAGNOSIS ..........................................799
Trouble Diagnosis Introduction .............................799
DTC Inspection Priority Chart ...............................802
Fail-safe Chart ......................................................803
Basic Inspection ...................................................805
Symptom Matrix Chart ..........................................809
Engine Control Component Parts Location ..........813
Circuit Diagram .....................................................817
ECM Harness Connector Terminal Layout ...........819
ECM Terminals and Reference Value ...................819
CONSULT-II Function ...........................................826
Generic Scan Tool (GST) Function .......................836
CONSULT-II Reference Value in Data Monitor .....838
Major Sensor Reference Graph in Data Monitor
Mode .....................................................................840
TROUBLE DIAGNOSIS - SPECIFICATION VALUE .843
Description ............................................................843Testing Condition ..................................................843
Inspection Procedure ........................................... .843
Diagnostic Procedure ............................................844
TROUBLE DIAGNOSIS FOR INTERMITTENT INCI-
DENT .......................................................................847
Description ............................................................847
Diagnostic Procedure ............................................847
POWER SUPPLY CIRCUIT FOR ECM ...................848
Wiring Diagram .....................................................848
ECM Terminals and Reference Value ...................849
Diagnostic Procedure ............................................849
Component Inspection ..........................................853
DTC U1000 CAN COMMUNICATION LINE ............854
Description ............................................................854
On Board Diagnosis Logic ....................................854
DTC Confirmation Procedure ................................854
Wiring Diagram .....................................................855
Diagnostic Procedure ............................................856
DTC P0011 IVT CONTROL .....................................857
Description ............................................................857
CONSULT-II Reference Value in Data Monitor Mode
.857
ECM Terminals and Reference Value ...................857
On Board Diagnosis Logic ....................................858
DTC Confirmation Procedure ................................858
Diagnostic Procedure ............................................859
DTC P0031, P0032 HO2S1 HEATER ......................860
Description ............................................................860
CONSULT-II Reference Value in Data Monitor Mode
.860
ECM Terminals and Reference Value ...................860
On Board Diagnosis Logic ....................................861
DTC Confirmation Procedure ................................861
Wiring Diagram .....................................................862
Diagnostic Procedure ............................................863
Component Inspection ..........................................864
Removal and Installation .......................................864
DTC P0037, P0038 HO2S2 HEATER .....................
.865
Description ............................................................865
CONSULT-II Reference Value in Data Monitor Mode
.865
ECM Terminals and Reference Value ...................865
On Board Diagnosis Logic ....................................866
DTC Confirmation Procedure ................................866
Wiring Diagram .....................................................867
Diagnostic Procedure ............................................868
Component Inspection ..........................................869
Removal and Installation .......................................869
DTC P0102, P0103 MAF SENSOR .........................870
Component Description ........................................870
CONSULT-II Reference Value in Data Monitor Mode
.870
ECM Terminals and Reference Value ...................870
On Board Diagnosis Logic ....................................870
DTC Confirmation Procedure ................................871
Wiring Diagram .....................................................872
Diagnostic Procedure ............................................873
Component Inspection ..........................................874
Removal and Installation .......................................875

EC-14
Component Inspection .........................................1097
Removal and Installation .....................................1098
REFRIGERANT PRESSURE SENSOR .................1099
Component Description .......................................1099
ECM Terminals and Reference Value ..................1099
Wiring Diagram ....................................................11 0 0
Diagnostic Procedure ..........................................11 0 1
Removal and Installation .....................................11 0 2
ELECTRICAL LOAD SIGNAL ...............................110 3
CONSULT-II Reference Value in Data Monitor Mode
11 0 3
ECM Terminals and Reference Value ..................11 0 3
Wiring Diagram ....................................................11 0 4
Diagnostic Procedure ..........................................11 0 6
DATA LINK CONNECTOR .....................................1111
Wiring Diagram ....................................................1111
EVAPORATIVE EMISSION SYSTEM ....................111 2
Description ...........................................................111 2
Component Inspection .........................................111 4
POSITIVE CRANKCASE VENTILATION ..............111 5
Description ...........................................................111 5
Component Inspection .........................................111 5
SERVICE DATA AND SPECIFICATIONS (SDS) ...111 7
Fuel Pressure ......................................................111 7
Idle Speed and Ignition Timing ............................111 7
Calculated Load Value .........................................111 7
Mass Air Flow Sensor ..........................................111 7
Intake Air Temperature Sensor ............................111 7
Engine Coolant Temperature Sensor ..................111 7
Heated Oxygen Sensor 1 Heater ........................111 7
Heated Oxygen sensor 2 Heater .........................111 7
Crankshaft Position Sensor (POS) ......................111 7
Camshaft Position Sensor (PHASE) ...................111 7
Throttle Control Motor ..........................................111 8
Injector .................................................................111 8
Fuel Pump ...........................................................111 8
QR20(WITHOUT EURO-OBD)
INDEX FOR DTC ....................................................111 9
Alphabetical Index ...............................................111 9
DTC No. Index .....................................................11 2 0
PRECAUTIONS ......................................................112 1
Precautions for Supplemental Restraint System
(SRS) “AIR BAG” and “SEAT BELT PRE-TEN-
SIONER” ..............................................................11 2 1
On Board Diagnostic (OBD) System of Engine and
A/T .......................................................................11 2 1
Precaution ...........................................................11 2 1
Wiring Diagrams and Trouble Diagnosis .............11 2 4
PREPARATION ......................................................112 5
Special Service Tools .......................................... 11 2 5
Commercial Service Tools ...................................11 2 5
ENGINE CONTROL SYSTEM ...............................112 7
System Diagram ..................................................11 2 7
Vacuum Hose Drawing ........................................11 2 8
System Chart .......................................................11 2 9
Multiport Fuel Injection (MFI) System ..................11 2 9
Electronic Ignition (EI) System ............................11 3 2Air Conditioning Cut Control ................................11 3 2
Fuel Cut Control (at No Load and High Engine
Speed) .................................................................11 3 3
CAN Communication ...........................................11 3 3
BASIC SERVICE PROCEDURE ............................11 35
Idle Speed and Ignition Timing Check .................11 3 5
Accelerator Pedal Released Position Learning ....11 3 6
Throttle Valve Closed Position Learning ..............11 3 6
Idle Air Volume Learning ......................................11 3 7
Fuel Pressure Check ...........................................11 3 9
ON BOARD DIAGNOSTIC (OBD) SYSTEM ..........11 41
Introduction ..........................................................11 4 1
Two Trip Detection Logic ......................................11 4 1
Emission-related Diagnostic Information .............11 4 1
NATS (Nissan Anti-theft System) .........................11 4 3
Malfunction Indicator (MI) ....................................11 4 4
TROUBLE DIAGNOSIS .........................................11 47
Trouble Diagnosis Introduction ............................11 4 7
DTC Inspection Priority Chart ..............................11 5 0
Fail-safe Chart .....................................................11 5 1
Basic Inspection ...................................................11 5 2
Symptom Matrix Chart .........................................11 5 6
Engine Control Component Parts Location ..........11 6 0
Circuit Diagram ....................................................11 6 4
ECM Harness Connector Terminal Layout ...........11 6 6
ECM Terminals and Reference Value ..................11 6 6
CONSULT-II Function ..........................................
11 7 3
CONSULT-II Reference Value in Data Monitor ....11 8 2
Major Sensor Reference Graph in Data Monitor
Mode ....................................................................11 8 5
TROUBLE DIAGNOSIS - SPECIFICATION VALUE 11 88
Description ...........................................................11 8 8
Testing Condition .................................................11 8 8
Inspection Procedure ........................................... 11 8 8
Diagnostic Procedure ........................................... 11 8 9
TROUBLE DIAGNOSIS FOR INTERMITTENT INCI-
DENT ......................................................................11 92
Description ...........................................................11 9 2
Diagnostic Procedure ........................................... 11 9 2
POWER SUPPLY CIRCUIT FOR ECM ..................11 93
Wiring Diagram ....................................................11 9 3
ECM Terminals and Reference Value ..................11 9 4
Diagnostic Procedure ........................................... 11 9 4
Component Inspection .........................................11 9 8
DTC U1000 CAN COMMUNICATION LINE ...........11 99
Description ...........................................................11 9 9
On Board Diagnosis Logic ...................................11 9 9
DTC Confirmation Procedure ...............................11 9 9
Wiring Diagram ....................................................1200
Diagnostic Procedure ........................................... 1201
DTC P0102, P0103 MAF SENSOR ........................1202
Component Description .......................................1202
CONSULT-II Reference Value in Data Monitor Mode
1202
ECM Terminals and Reference Value ..................1202
On Board Diagnosis Logic ...................................1203
DTC Confirmation Procedure ...............................1203
Wiring Diagram ....................................................1205
Diagnostic Procedure ........................................... 1206

ENGINE CONTROL SYSTEM
EC-33
[QR25(WITH EURO-OBD)]
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EC
System ChartEBS00M0B
*1: This sensor is not used to control the engine system under normal conditions.
*2: These signals are sent to the ECM through CAN communication line.
Multiport Fuel Injection (MFI) SystemEBS00M0C
INPUT/OUTPUT SIGNAL CHART
*1: Under normal conditions, this sensor is not for engine control operation.
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
Input (Sensor) ECM Function Output (Actuator)
●Camshaft position sensor (PHASE)
●Crankshaft position sensor (POS)
●Mass air flow sensor
●Engine coolant temperature sensor
●Heated oxygen sensor 1
●Throttle position sensor
●Accelerator pedal position sensor
●Park/neutral position (PNP) switch
●Intake air temperature sensor
●Power steering pressure sensor
●Ignition switch
●Battery voltage
●Knock sensor
●Refrigerant pressure sensor
●Heated oxygen sensor 2 *1
●TCM (Transmission control module) *2
●Wheel sensor
●Air conditioner switch
●Electrical loadFuel injection & mixture ratio control Fuel injectors
Electronic ignition system Power transistors
Fuel pump control Fuel pump relay
On board diagnostic system MI (On the instrument panel)
Heated oxygen sensor 1 heater control Heated oxygen sensor 1 heater
Heated oxygen sensor 2 heater control Heated oxygen sensor 2 heater
Power valve control VIAS control solenoid valve
EVAP canister purge flow controlEVAP canister purge volume control
solenoid valve
Air conditioning cut control Air conditioner relay
Cooling fan control Cooling fan relays
Sensor Input Signal to ECMECM func-
tionActuator
Crankshaft position sensor (POS)
Engine speed
Piston position
Fuel injec-
tion & mix-
ture ratio
controlFuel injectors Camshaft position sensor (PHASE)
Mass air flow sensor Amount of intake air
Engine coolant temperature sensor Engine coolant temperature
Heated oxygen 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
Ignition switch Start signal
Knock sensor Engine knocking condition
Battery Battery voltage
Power steering pressure sensor Power steering operation
Heated oxygen sensor 2 *
1Density of oxygen in exhaust gas
Wheel sensor Vehicle speed
Air conditioner switch Air conditioner operation

ENGINE CONTROL SYSTEM
EC-35
[QR25(WITH EURO-OBD)]
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EC
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) SystemEBS00M0D
INPUT/OUTPUT SIGNAL CHART
SEF337W
Sensor Input Signal to ECMECM func-
tionActuator
Crankshaft position sensor (POS)
Engine speed
Piston position
Ignition
timing con-
trolPower 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
Ignition switch Start signal
Knock sensor Engine knocking
Park/neutral position (PNP) switch Gear position
Battery Battery voltage
Wheel sensor Vehicle speed