PHASE NISSAN ALMERA N16 2003 Electronic Repair Manual

ROCKER COVER
EM-29
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ROCKER COVERPFP:13264
Removal and InstallationEBS00LQA
CAUTION:
Apply new engine oil when installing the parts that specified to do so in the figure.
REMOVAL
1. Move harnesses on top surface and right side of rocker cover, and move them aside.
2. Remove ignition coil. Refer to EM-24, "
Removal and Installation" .
3. Disconnect PCV hoses on rocker cover side.
4. If necessary, remove PCV control valve.
5. If necessary, remove intake valve timing control solenoid valve and camshaft position sensor (PHASE).
CAUTION:
●Do not shock it.
●Do not disassemble it.
●Tip of camshaft position sensor (PHASE) generates strong magnetic fields. Keep it away from
metal particles or objects affected by magnetic fields.
KBIA1375E
1. PCV hose 2. Rocker cover 3. Grommet
4. PCV control valve 5. PCV hose 6.Intake valve timing control solenoid
valve
7. O-ring 8. Oil filter cap 9. Gasket
10. Gasket 11. Rocker cover oil seal 12. Gasket
13. O-ring 14. Camshaft position sensor (PHASE)

ROCKER COVER
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d. Tighten mounting screws to specified torque in 2 or more steps
in numerical order shown in figure.
3. Install intake valve timing control solenoid valve and camshaft position sensor (PHASE).
●Tighten bolt after fully inserting it into rocker cover.
4. Install PCV valve.
●Insert until flange contacts grommet tightly.
5. Install remaining parts in the reverse order of removal.Bolt length: Bolt position
25 mm (0.98 in) : 1
65 mm (2.56 in) : 2
20 mm (0.79 in) : Except the above (all circumference)
KBIA1376E

SERVICE DATA AND SPECIFICATIONS (SDS)
EM-105
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Intake valve timing control solenoid valve
6.3 - 8.3 (0.64 - 0.85, 56 - 73)*2
Camshaft position sensor (PHASE)
7.2 - 10.8 (0.73 - 1.1, 64 - 95) *2
Camshaft sprocket (INT) 78.4 - 88.2 (8.0 - 9.0, 58 - 65)
Camshaft sprocket (EXH) 98.1 - 127.5 (10.0 - 13.0, 73 - 94)
*1 Camshaft bracket 1)
2.0 (0.2, 18) *
2
2)
5.9 (0.6, 52) *2
3)
9.0 - 11.8 (0.92 - 1.20, 80 - 104)*2
Crankshaft pulley132.4 - 152.0 (14.0 - 15.0, 98 - 112)
Front cover
6.92 - 9.51 (0.71 - 0.97, 62 - 84)*
2
Timing chain tension guide 15.7 - 20.6 (1.6 - 2.1, 12 - 15)
*1 Cylinder head 1) 29.4 (3.0, 22)
2) 58.8 (6.0, 43)
3) 0 (0.0, 0)
4) 27.4 - 31.4 (2.8 - 3.2, 21 - 23)
5) 50° - 55° (Angle tightening)
Cylinder head front cover
6.92 - 9.5 (0.71 - 0.96, 62 - 84)*
2
Flywheel (M/T)83.4 - 93.2 (8.5 - 9.5, 62 - 68)
Drive plate (A/T)93.2 - 103 (9.5 - 10.5, 69 - 75)
*1 Connecting rod bearing cap 1) 13.72 - 15.68 (1.4 - 1.5, 10.2 - 11 . 5 )
2) 35° - 40° (Angle tightening)
Knock sensor15.7 - 20.6 (1.6 - 2.1, 12 - 15)
Crankshaft position sensor (POS)
7.2 - 10.8 (0.8 - 1.1, 64 - 95)*
2
Rear oil seal retainer
6.3 - 8.3 (0.65 - 0.84, 56 - 73)*2
Signal plate
7.6 - 9.2 (0.78 - 0.93, 68 - 81)*2

EC-3
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ECA Component Inspection ......................................... 204
Removal and Installation ...................................... 204
DTC P0222, P0223 TP SENSOR ........................... 205
Component Description ........................................ 205
CONSULT-II Reference Value in Data Monitor Mode
. 205
On Board Diagnosis Logic ................................... 205
DTC Confirmation Procedure ............................... 205
Wiring Diagram .................................................... 207
Diagnostic Procedure ........................................... 208
Component Inspection ......................................... 210
Removal and Installation ...................................... 210
DTC P0226 APP SENSOR ......................................211
Component Description ......................................... 211
CONSULT-II Reference Value in Data Monitor Mode
.. 211
On Board Diagnosis Logic .................................... 211
DTC Confirmation Procedure ................................ 211
Wiring Diagram .................................................... 213
Diagnostic Procedure ........................................... 214
Component Inspection ......................................... 216
Removal and Installation ...................................... 217
DTC P0227, P0228 APP SENSOR ........................ 218
Component Description ........................................ 218
CONSULT-II Reference Value in Data Monitor Mode
. 218
On Board Diagnosis Logic ................................... 218
DTC Confirmation Procedure ............................... 218
Wiring Diagram .................................................... 220
Diagnostic Procedure ........................................... 221
Component Inspection ......................................... 223
Removal and Installation ...................................... 224
DTC P0300 - P0304 MULTIPLE CYLINDER MIS-
FIRE, NO. 1 - 4 CYLINDER MISFIRE ..................... 225
On Board Diagnosis Logic ................................... 225
DTC Confirmation Procedure ............................... 225
Diagnostic Procedure ........................................... 226
DTC P0327, P0328 KS ........................................... 230
Component Description ........................................ 230
On Board Diagnosis Logic ................................... 230
DTC Confirmation Procedure ............................... 230
Wiring Diagram .................................................... 231
Diagnostic Procedure ........................................... 232
Component Inspection ......................................... 233
Removal and Installation ...................................... 233
DTC P0335 CKP SENSOR (POS) .......................... 234
Component Description ........................................ 234
CONSULT-II Reference Value in Data Monitor Mode
. 234
On Board Diagnosis Logic ................................... 234
DTC Confirmation Procedure ............................... 234
Wiring Diagram ...................................................
. 235
Diagnostic Procedure ........................................... 236
Component Inspection ......................................... 238
Removal and Installation ...................................... 239
DTC P0340 CMP SENSOR (PHASE) ..................... 240
Component Description ........................................ 240
On Board Diagnosis Logic ................................... 240
DTC Confirmation Procedure ............................... 240Wiring Diagram .....................................................241
Diagnostic Procedure ...........................................242
Component Inspection ..........................................244
Removal and Installation ......................................245
DTC P0420 THREE WAY CATALYST FUNCTION . 246
On Board Diagnosis Logic ....................................246
DTC Confirmation Procedure ...............................246
Overall Function Check ........................................247
Diagnostic Procedure ...........................................248
DTC P0444 EVAP CANISTER PURGE VOLUME
CONTROL SOLENOID VALVE ...............................251
Description ............................................................251
CONSULT-II Reference Value in Data Monitor Mode
.251
On Board Diagnosis Logic ....................................252
DTC Confirmation Procedure ...............................252
Wiring Diagram .....................................................253
Diagnostic Procedure ...........................................254
Component Inspection ..........................................256
Removal and Installation ......................................256
DTC P0500 VSS ......................................................257
Description ............................................................257
On Board Diagnosis Logic ....................................257
DTC Confirmation Procedure ...............................257
Overall Function Check ........................................258
Diagnostic Procedure ...........................................259
DTC P0550 PSP SENSOR .....................................260
Component Description ........................................260
CONSULT-II Reference Value in Data Monitor Mode
.260
On Board Diagnosis Logic ....................................260
DTC Confirmation Procedure ...............................260
Wiring Diagram .....................................................261
Diagnostic Procedure ...........................................262
Component Inspection ..........................................264
DTC P0605 ECM .....................................................265
Component Description ........................................265
On Board Diagnosis Logic ....................................265
DTC Confirmation Procedure ...............................265
Diagnostic Procedure ...........................................266
DTC P1065 ECM POWER SUPPLY .......................268
Component Description ........................................268
On Board Diagnosis Logic ....................................268
DTC Confirmation Procedure ...............................268
Wiring Diagram .....................................................269
Diagnostic Procedure ...........................................270
DTC P1111 IVT CONTROL SOLENOID VALVE .....272
Component Description ........................................272
CONSULT-II Reference Value in Data Monitor Mode
.272
On Board Diagnosis Logic ....................................272
DTC Confirmation Procedure ...............................272
Wiring Diagram .....................................................273
Diagnostic Procedure ...........................................274
Component Inspection ..........................................275
Removal and Installation ......................................275
DTC P1121 ELECTRIC THROTTLE CONTROL
ACTUATOR .............................................................276
Component Description ........................................276

EC-5
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ECA Wiring Diagram .................................................... 353
Diagnostic Procedure ........................................... 354
DTC P1706 PNP SWITCH ...................................... 356
Component Description ........................................ 356
CONSULT-II Reference Value in Data Monitor Mode
. 356
On Board Diagnosis Logic ................................... 356
DTC Confirmation Procedure ............................... 356
Overall Function Check ........................................ 357
Wiring Diagram .................................................... 358
Diagnostic Procedure ........................................... 359
DTC P1805 BRAKE SWITCH ................................ 360
Description ........................................................... 360
CONSULT-II Reference Value in Data Monitor Mode
. 360
On Board Diagnosis Logic ................................... 360
DTC Confirmation Procedure ............................... 360
Wiring Diagram .................................................... 361
Diagnostic Procedure ........................................... 362
Component Inspection ......................................... 364
IGNITION SIGNAL .................................................. 365
Component Description ........................................ 365
Wiring Diagram .................................................... 366
Diagnostic Procedure ........................................... 369
Component Inspection ......................................... 373
Removal and Installation ...................................... 374
INJECTOR CIRCUIT ............................................... 375
Component Description ........................................ 375
CONSULT-II Reference Value in Data Monitor Mode
. 375
Wiring Diagram .................................................... 376
Diagnostic Procedure ........................................... 377
Component Inspection ......................................... 380
Removal and Installation ...................................... 380
FUEL PUMP CIRCUIT ............................................ 381
Description ........................................................... 381
CONSULT-II Reference Value in Data Monitor Mode
. 381
Wiring Diagram .................................................... 382
Diagnostic Procedure ........................................... 383
Component Inspection ......................................... 385
Removal and Installation ...................................... 386
REFRIGERANT PRESSURE SENSOR ................. 387
Component Description ........................................ 387
Wiring Diagram .................................................... 388
Diagnostic Procedure ........................................... 389
Removal and Installation ...................................... 391
ELECTRICAL LOAD SIGNAL ................................ 392
Description ...................................................
........ 392
CONSULT-II Reference Value in Data Monitor Mode
. 392
Wiring Diagram .................................................... 393
Diagnostic Procedure ........................................... 394
MI & DATA LINK CONNECTORS .......................... 397
Wiring Diagram—LHD Models ............................. 397
Wiring Diagram—RHD Models ............................ 398
EVAPORATIVE EMISSION SYSTEM ..................... 399
Description ........................................................... 399
Component Inspection ......................................... 401POSITIVE CRANKCASE VENTILATION ...............402
Description ............................................................402
Component Inspection ..........................................402
SERVICE DATA AND SPECIFICATIONS (SDS) ....404
Fuel Pressure .......................................................404
Idle Speed and Ignition Timing .............................404
Calculated Load Value ..........................................404
Mass Air Flow Sensor ...........................................404
Intake Air Temperature Sensor .............................404
Engine Coolant Temperature Sensor ...................404
Heated Oxygen Sensor 1 Heater .........................404
Heated Oxygen sensor 2 Heater ..........................404
Crankshaft Position Sensor (POS) .......................404
Camshaft Position Sensor (PHASE) ....................404
Throttle Control Motor ...........................................405
Injector ..................................................................405
Fuel Pump ............................................................405
QG (WITHOUT EURO-OBD)
INDEX FOR DTC .....................................................406
Alphabetical Index ................................................406
DTC No. Index ......................................................407
PRECAUTIONS ......................................................409
Precautions for Supplemental Restraint System
(SRS) “AIR BAG” and “SEAT BELT PRE-TEN-
SIONER” ...............................................................409
On Board Diagnostic (OBD) System of Engine ....409
Precaution ............................................................409
Wiring Diagrams and Trouble Diagnosis ..............412
PREPARATION .......................................................413
Special Service Tools ...........................................413
Commercial Service Tools ....................................413
ENGINE CONTROL SYSTEM ................................415
System Diagram ...................................................415
Vacuum Hose Drawing .........................................416
System Chart ........................................................417
Multiport Fuel Injection (MFI) System ...................417
Electronic Ignition (EI) System .............................419
Air Conditioning Cut Control .................................420
Fuel Cut Control (at No Load and High Engine
Speed) ..................................................................421
CAN Communication ............................................421
BASIC SERVICE PROCEDURE .............................424
Idle Speed and Ignition Timing Check ..................424
Accelerator Pedal Released Position Learning ....425
Throttle Valve Closed Position Learning ...............425
Idle Air Volume Learning ......................................425
Fuel Pressure Check ............................................427
ON BOARD DIAGNOSTIC (OBD) SYSTEM ..........429
Introduction ...........................................................429
Two Trip Detection Logic ......................................429
Emission-related Diagnostic Information ..............429
NATS (Nissan Anti-theft System) .........................431
Malfunction Indicator (MI) .....................................432
TROUBLE DIAGNOSIS ..........................................436
Trouble Diagnosis Introduction .............................436
DTC Inspection Priority Chart ...............................440
Fail-safe Chart ......................................................441

EC-7
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ECA Component Inspection ......................................... 548
Removal and Installation ...................................... 549
DTC P0327, P0328 KS ........................................... 550
Component Description ........................................ 550
On Board Diagnosis Logic ................................... 550
DTC Confirmation Procedure ............................... 550
Wiring Diagram .................................................... 551
Diagnostic Procedure ........................................... 552
Component Inspection ......................................... 553
Removal and Installation ...................................... 553
DTC P0335 CKP SENSOR (POS) .......................... 554
Component Description ........................................ 554
CONSULT-II Reference Value in Data Monitor Mode
. 554
On Board Diagnosis Logic ................................... 554
DTC Confirmation Procedure ............................... 554
Wiring Diagram .................................................... 556
Diagnostic Procedure ........................................... 557
Component Inspection ......................................... 559
Removal and Installation ...................................... 560
DTC P0340 CMP SENSOR (PHASE) ..................... 561
Component Description ........................................ 561
On Board Diagnosis Logic ................................... 561
DTC Confirmation Procedure ............................... 561
Wiring Diagram .................................................... 563
Diagnostic Procedure ........................................... 564
Component Inspection ......................................... 566
Removal and Installation ...................................... 567
DTC P0605 ECM .................................................... 568
Component Description ........................................ 568
On Board Diagnosis Logic ................................... 568
DTC Confirmation Procedure ............................... 568
Diagnostic Procedure ........................................... 570
DTC P1065 ECM POWER SUPPLY ....................... 571
Component Description ........................................ 571
On Board Diagnosis Logic ................................... 571
DTC Confirmation Procedure ............................... 571
Wiring Diagram .................................................... 572
Diagnostic Procedure ........................................... 573
DTC P1121 ELECTRIC THROTTLE CONTROL
ACTUATOR ............................................................ 575
Component Description ........................................ 575
On Board Diagnosis Logic ................................... 575
DTC Confirmation Procedure ............................... 575
Diagnostic Procedure ........................................... 576
Removal and Installation ...................................... 577
DTC P1122 ELECTRIC THROTTLE CONTROL
FUNCTION .............................................................. 578
Description ..........................................................
. 578
On Board Diagnosis Logic ................................... 578
DTC Confirmation Procedure ............................... 578
Wiring Diagram .................................................... 579
Diagnostic Procedure ........................................... 580
Component Inspection ......................................... 584
Removal and Installation ...................................... 584
DTC P1124, P1126 THROTTLE CONTROL MOTOR
RELAY .................................................................... 585
Component Description ........................................ 585
CONSULT-II Reference Value in Data Monitor Mode .585
On Board Diagnosis Logic ....................................585
DTC Confirmation Procedure ...............................585
Wiring Diagram .....................................................587
Diagnostic Procedure ...........................................588
Component Inspection ..........................................590
DTC P1128 THROTTLE CONTROL MOTOR .........591
Component Description ........................................591
On Board Diagnosis Logic ....................................591
DTC Confirmation Procedure ...............................591
Wiring Diagram .....................................................592
Diagnostic Procedure ...........................................593
Component Inspection ..........................................594
Removal and Installation ......................................595
DTC P1217 ENGINE OVER TEMPERATURE ........596
System Description ...............................................596
CONSULT-II Reference Value in Data Monitor Mode
.596
On Board Diagnosis Logic ....................................597
Overall Function Check ........................................597
Wiring Diagram .....................................................599
Diagnostic Procedure ...........................................600
Main 12 Causes of Overheating ...........................605
Component Inspection ..........................................606
DTC P1223, P1224 TP SENSOR ............................607
Component Description ........................................607
CONSULT-II Reference Value in Data Monitor Mode
.607
On Board Diagnosis Logic ....................................607
DTC Confirmation Procedure ...............................607
Wiring Diagram .....................................................609
Diagnostic Procedure ...........................................610
Component Inspection ..........................................612
Removal and Installation ......................................612
DTC P1225 TP SENSOR ........................................613
Component Description ........................................613
On Board Diagnosis Logic ....................................613
DTC Confirmation Procedure ...............................613
Diagnostic Procedure ...........................................614
Removal and Installation ......................................614
DTC P1226 TP SENSOR .......................................
.615
Component Description ........................................615
On Board Diagnosis Logic ....................................615
DTC Confirmation Procedure ...............................615
Diagnostic Procedure ...........................................616
Removal and Installation ......................................616
DTC P1227, P1228 APP SENSOR .........................617
Component Description ........................................617
CONSULT-II Reference Value in Data Monitor Mode
.617
On Board Diagnosis Logic ....................................617
DTC Confirmation Procedure ...............................617
Wiring Diagram .....................................................619
Diagnostic Procedure ...........................................620
Component Inspection ..........................................622
Removal and Installation ......................................623
DTC P1229 SENSOR POWER SUPPLY ................624
On Board Diagnosis Logic ....................................624
DTC Confirmation Procedure ...............................624

EC-9
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ECA EVAPORATIVE EMISSION SYSTEM ..................... 717
Description ........................................................... 717
Component Inspection ......................................... 719
POSITIVE CRANKCASE VENTILATION ............... 720
Description ........................................................... 720
Component Inspection ......................................... 720
SERVICE DATA AND SPECIFICATIONS (SDS) .... 722
Fuel Pressure ....................................................... 722
Idle Speed and Ignition Timing ............................. 722
Calculated Load Value ......................................... 722Mass Air Flow Sensor ...........................................722
Intake Air Temperature Sensor .............................722
Engine Coolant Temperature Sensor ...................722
Heated Oxygen Sensor 1 Heater .........................722
Heated Oxygen sensor 2 Heater ..........................722
Crankshaft Position Sensor (POS) .......................722
Camshaft Position Sensor (PHASE) ....................722
Throttle Control Motor ...........................................723
Injector ..................................................................723
Fuel Pump ............................................................723

EC-16
[QG (WITH EURO-OBD)]
PRECAUTIONS
●Do not disassemble ECM.
●If battery cable is disconnected, the memory will return to
the initial ECM values.
The ECM will now start to self-control at its initial values.
Engine operation can vary slightly when the cable is dis-
connected. However, this is not an indication of a malfunc-
tion. Do not replace parts because of a slight variation.
●When connecting ECM harness connector, fasten it
securely with levers as far as they will go as shown at right.
●When connecting or disconnecting pin connectors into or
from ECM, take care not to damage pin terminals (bend or
break).
Make sure that there are not any bends or breaks on ECM
pin terminal, when connecting pin connectors.
●Securely connect ECM harness connectors.
A poor connection can cause an extremely high (surge)
voltage to develop in coil and condenser, thus resulting in
damage to ICs.
●Keep engine control system harness at least 10 cm (4 in)
away from adjacent harness, to prevent engine control sys-
tem malfunctions due to receiving external noise, degraded
operation of ICs, etc.
●Keep engine control system parts and harness dry.
●Before replacing ECM, perform “ECM Terminals and Refer-
ence Value” inspection and make sure ECM functions prop-
erly. Refer to EC-80, "
ECM Terminals and Reference Value" .
●Handle mass air flow sensor carefully to avoid damage.
●Do not disassemble mass air flow sensor.
●Do not clean mass air flow sensor with any type of deter-
gent.
●Do not disassemble electric throttle control actuator.
●Even a slight leak in the air intake system can cause seri-
ous incidents.
●Do not shock or jar the camshaft position sensor (PHASE),
crankshaft position sensor (POS).
PBIB1164E
MBIB0145E
PBIB0090E
MEF040D

ENGINE CONTROL SYSTEM
EC-23
[QG (WITH EURO-OBD)]
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System ChartEBS00K34
*1: This sensor is not used to control the engine system under normal conditions.
*2: The signals are sent to the ECM through CAN communication line.
*3: The output signals are sent from the ECM through CAN communication line.
Multiport Fuel Injection (MFI) SystemEBS00K35
INPUT/OUTPUT SIGNAL CHART
*1: Under normal conditions, this sensor is not for engine control operation.
*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
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
●Stop lamp switch
●Battery voltage
●Knock sensor
●Refrigerant pressure sensor
●Heated oxygen sensor 2*1
●TCM (Transmission control module)*2
●Air conditioner switch*2
●Vehicle speed signal*2
●Electrical load signal*2
Fuel injection & mixture ratio control Fuel injectors
Electronic ignition system Power transistor
Fuel pump control Fuel pump relay
On board diagnostic system
MI (On the instrument panel)
*3
Intake valve timing controlIntake valve timing control solenoid
valve
Heated oxygen sensor 1 heater control Heated oxygen sensor 1 heater
Heated oxygen sensor 2 heater control Heated oxygen sensor 2 heater
EVAP canister purge flow controlEVAP canister purge volume control
solenoid valve
Air conditioning cut control
Air conditioner relay
*3
Cooling fan control
Cooling fan relay*3
Sensor Input Signal to ECM ECM Function Actuator
Crankshaft position sensor (POS)
Camshaft position sensor (PHASE)Engine speed
*3 and piston position
Fuel injection & mixture
ratio controlFuel injectors 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
Knock sensor Engine knocking condition
Battery
Battery voltage
*3
Power steering pressure sensor Power steering operation
Heated oxygen sensor 2
*1Density of oxygen in exhaust gas
Vehicle speed signal
*2Vehicle speed
Air conditioner switch
*2Air conditioner operation

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