2001 INFINITI QX4 Fuel

DTC*1Items
(CONSULT-II screen terms)Reference page
P0217 ENG OVER TEMP EC-314
P0300 MULTI CYL MISFIRE EC-320
P0301 CYL 1 MISFIRE EC-320
P0302 CYL 2 MISFIRE EC-320
P0303 CYL 3 MISFIRE EC-320
P0304 CYL 4 MISFIRE EC-320
P0305 CYL 5 MISFIRE EC-320
P0306 CYL 6 MISFIRE EC-320
P0325*2 KNOCK SEN/CIRC-B1 EC-328
P0335 CPS/CIRCUIT (POS) EC-334
P0340 CAM PS/CIRC (PHS) EC-342
P0420 TW CATALYST SYS-B1 EC-347
P0430 TW CATALYST SYS-B2 EC-347
P0440 EVAP SMALL LEAK EC-352
P0443 PURG VOLUME CONT/V EC-367
P0446 VENT CONTROL VALVE EC-374
P0450 EVAP SYS PRES SEN EC-381
P0455 EVAP GROSS LEAK EC-394
P0460 FUEL LV SE (SLOSH) EC-407
P0461 FUEL LEVEL SENSOR EC-411
P0464 FUEL LEVL SEN/CIRC EC-413
P0500 VEH SPEED SEN/CIRC*4 EC-417
P0505 IACV/AAC VLV/CIRC EC-422
P0510 CLOSED TP SW/CIRC EC-431
P0600*2 A/T COMM LINE EC-440
P0605 ECMEC-444
P0705 PNP SW/CIRC AT-111
P0710 ATF TEMP SEN/CIRC AT-116
P0720 VEH SPD SEN/CIR A/T*4 AT-124
P0725 ENGINE SPEED SIG AT-130
P0731 A/T 1ST GR FNCTN AT-136
P0732 A/T 2ND GR FNCTN AT-143
P0733 A/T 3RD GR FNCTN AT-151
P0734 A/T 4TH GR FNCTN AT-157
P0740 TCC SOLENOID/CIRC AT-165
P0744 A/T TCC S/V FNCTN AT-170
P0745 L/PRESS SOL/CIRC AT-174
TROUBLE DIAGNOSIS Ð INDEX
Alphabetical & P No. Index for DTC (Cont'd)
EC-12

DTC*1Items
(CONSULT-II screen terms)Reference page
P0750 SFT SOL A/CIRC*3 AT-180
P0755 SFT SOL B/CIRC*3 AT-189
P1110 INT/V TIM CONT-B1 EC-446
P 1111INT/V TIM V/CIR-B1 EC-451
P1130 SWIRL CONT SOL/V EC-458
P1135 INT/V TIM CONT-B2 EC-446
P1136 INT/V TIM V/CIR-B2 EC-451
P1140 INTK TIM S/CIRC-B1 EC-482
P1145 INTK TIM S/CIRC-B2 EC-482
P1148 CLOSED LOOP-B1 EC-491
P1165 SWL CON VC SW/CIRC EC-493
P1168 CLOSED LOOP-B2 EC-491
P1217 ENG OVER TEMP LC-24
P1320 IGN SIGNAL-PRIMARY EC-499
P1335 CPS/CIRCUIT (REF) EC-510
P1336 CPS/CIRC (POS) COG EC-517
P1441 EVAP VERY SMALL LEAK EC-526
P1444 PURG VOLUME CONT/V EC-541
P1446 VENT CONTROL VALVE EC-553
P1447 EVAP PURG FLOW/MON EC-561
P1448 VENT CONTROL VALVE EC-573
P1464 FUEL LEVEL SEN/CIRC EC-582
P1490 VC/V BYPASS/V EC-585
P1491 VC CUT/V BYPASS/V EC-591
P1605 A/T DIAG COMM LINE EC-603
P1610 - P1615*2 NATS MALFUNCTION EL-328
P1705 TP SEN/CIRC A/T*3 AT-218
P1706 P-N POS SW/CIRCUIT EC-604
P1760 O/R CLTCH SOL/CIRC AT-223
*1: 1st trip DTC No. is the same as DTC No.
*2: This DTC is displayed with CONSULT-II only.
*3: When the fail-safe operation occurs, the MIL illuminates.
*4: The MIL illuminates when both the ªRevolution sensor signalº and the ªVehicle speed sensor signalº meet the fail-safe condition at
the same time.
NOTE:
IRegarding R50 models, ª-B1º and ªBK1º indicate right bank and ª-B2º and ªBK2º indicate left bank.
IBank 1 (-B1 or BK1) includes No. 1 cylinder.
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TROUBLE DIAGNOSIS Ð INDEX
Alphabetical & P No. Index for DTC (Cont'd)
EC-13

Supplemental Restraint System (SRS) ªAIR
BAGº and ªSEAT BELT PRE-TENSIONERº
NBEC0002The Supplemental Restraint System such as ªAIR BAGº and ªSEAT BELT PRE-TENSIONERº used along with
a seat belt, helps to reduce the risk or severity of injury to the driver and front passenger for certain types of
collision. The SRS system composition which is available to INFINITI QX4 is as follows:
IFor a frontal collision
The Supplemental Restraint System consists of driver air bag module (located in the center of the steer-
ing wheel), front passenger air bag module (located on the instrument panel on passenger side), seat belt
pre-tensioners, a diagnosis sensor unit, warning lamp, wiring harness and spiral cable.
IFor a side collision
The Supplemental Restraint System consists of front side air bag module (located in the outer side of front
seat), satellite sensor, diagnosis sensor unit (one of components of air bags for a frontal collision), wiring
harness, warning lamp (one of components of air bags for a frontal collision).
Information necessary to service the system safely is included in theRS sectionof this Service Manual.
WARNING:
ITo avoid rendering the SRS inoperative, which could increase the risk of personal injury or death
in the event of a collision which would result in air bag inflation, all maintenance must be performed
by an authorized INFINITI dealer.
IImproper maintenance, including incorrect removal and installation of the SRS, can lead to per-
sonal injury caused by unintentional activation of the system. For removal of Spiral Cable and Air
Bag Module, see the RS section.
IDo not use electrical test equipment on any circuit related to the SRS unless instructed to in this
Service Manual. Spiral cable and wiring harnesses covered with yellow insulation tape either just
before the harness connectors or for the complete harness are related to the SRS.
Precautions for On Board Diagnostic (OBD)
System of Engine and A/T
NBEC0003The ECM has an on board diagnostic system. It will light up the malfunction indicator lamp (MIL) to warn the
driver of a malfunction causing emission deterioration.
CAUTION:
IBe sure to turn the ignition switch OFF and disconnect the negative battery terminal before any
repair or inspection work. The open/short circuit of related switches, sensors, solenoid valves, etc.
will cause the MIL to light up.
IBe sure to connect and lock the connectors securely after work. A loose (unlocked) connector will
cause the MIL to light up due to the open circuit. (Be sure the connector is free from water, grease,
dirt, bent terminals, etc.)
ICertain systems and components, especially those related to OBD, may use a new style slide-
locking type harness connector. For description and how to disconnect, refer to EL-6, ªHARNESS
CONNECTOR (SLIDE-LOCKING TYPE)º.
IBe sure to route and secure the harnesses properly after work. The interference of the harness with
a bracket, etc. may cause the MIL to light up due to the short circuit.
IBe sure to connect rubber tubes properly after work. A misconnected or disconnected rubber tube
may cause the MIL to light up due to the malfunction of the fuel injection system, etc.
IBe sure to erase the unnecessary malfunction information (repairs completed) from the ECM and
TCM (Transmission control module) before returning the vehicle to the customer.
PRECAUTIONS
Supplemental Restraint System (SRS) ªAIR BAGº and ªSEAT BELT PRE-TENSIONERº
EC-14

Engine Fuel & Emission Control SystemNBEC0004
SEF952RE
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PRECAUTIONS
Engine Fuel & Emission Control System
EC-15

Special Service ToolsNBEC0007The actual shapes of Kent-Moore tools may differ from those of special service tools illustrated here.
Tool number
(Kent-Moore No.)
Tool nameDescription
KV10117100
(J36471-A)
Front heated oxygen
sensor wrench
Rear heated oxygen
sensor wrench
NT379
Loosening or tightening front and rear heated oxy-
gen sensors with 22 mm (0.87 in) hexagon nut
(J44321)
Fuel pressure adapter
and gauge kit
SEF326Z
Checking fuel pressure with pressure gauge
Commercial Service ToolsNBEC0008
Tool name
(Kent-Moore No.)Description
Leak detector
(J41416)
NT703
Locating the EVAP leak
EVAP service port
adapter
(J41413-OBD)
NT704
Applying positive pressure through EVAP service
port
Fuel filler cap adapter
NT653
Checking fuel tank vacuum relief valve opening
pressure
PREPARATION
Special Service Tools
EC-18

System ChartNBEC0013
Input (Sensor) ECM Function Output (Actuator)
ICamshaft position sensor (PHASE)
ICrankshaft position sensor (REF)
IMass air flow sensor
IEngine coolant temperature sensor
IHeated oxygen sensor 1 (front)
IIgnition switch
IThrottle position sensor
IClosed throttle position switch*3
IPark/neutral position (PNP) switch
IAir conditioner switch
IKnock sensor
IIntake air temperature sensor
IAbsolute pressure sensor
IEVAP control system pressure sensor*1
IBattery voltage
IPower steering oil pressure switch
IVehicle speed sensor
IFuel tank temperature sensor*1
ICrankshaft position sensor (POS)
IHeated oxygen sensor 2 (rear)*2
ITCM (Transmission control module)
IRefrigerant pressure sensor
IElectrical load
IFuel level sensor*1Fuel injection & mixture ratio control Injectors
Electronic ignition system Power transistor
Idle air control system IACV-AAC valve
Fuel pump control Fuel pump relay
On board diagnostic system MIL (On the instrument panel)
Swirl control valve controlSwirl control valve control solenoid
valve
Power valve control VIAS control solenoid valve
Heated oxygen sensor 1 heater (front) con-
trolHeated oxygen sensor 1 heater
(front)
Heated oxygen sensor 2 heater (rear) controlHeated oxygen sensor 2 heater
(rear)
EVAP canister purge flow controlEVAP canister purge volume con-
trol solenoid valve
Air conditioning cut control Air conditioner relay
ON BOARD DIAGNOSIS for EVAP systemIEVAP canister vent control valve
IVacuum cut valve bypass valve
*1: These sensors are not used to control the engine system. They are used only for the on board diagnosis.
*2: This sensor is not used to control the engine system under normal conditions.
*3: This switch will operate in place of the throttle position sensor to control EVAP parts if the sensor malfunctions.GI
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ENGINE AND EMISSION CONTROL OVERALL SYSTEM
System Chart
EC-27

Multiport Fuel Injection (MFI) System
DESCRIPTIONNBEC0014Input/Output Signal ChartNBEC0014S01
Sensor Input Signal to ECMECM func-
tionActuator
Crankshaft position sensor (POS) Engine speed (POS signal)
Fuel injec-
tion & mix-
ture ratio
controlInjectors Crankshaft position sensor (REF) Engine speed (REF signal)
Camshaft position sensor (PHASE) Piston position
Mass air flow sensor Amount of intake air
Engine coolant temperature sensor Engine coolant temperature
Heated oxygen sensor 1 (front) Density of oxygen in exhaust gas
Throttle position sensorThrottle position
Throttle valve idle position
Park/neutral position (PNP) switch Gear position
Vehicle speed sensor Vehicle speed
Ignition switch Start signal
Air conditioner switch Air conditioner operation
Knock sensor Engine knocking condition
Battery Battery voltage
Absolute pressure sensor Ambient air barometric pressure
Power steering oil pressure switch Power steering operation
Heated oxygen sensor 2 (rear)* Density of oxygen in exhaust gas
*: Under normal conditions, this sensor is not for engine control operation.
Basic Multiport Fuel Injection SystemNBEC0014S02The amount of fuel injected from the fuel injector is determined by the ECM. The ECM controls the length of
time the valve remains open (injection pulse duration). The amount of fuel injected is a program value in the
ECM memory. The program value is preset by engine operating conditions. These conditions are determined
by input signals (for engine speed and intake air) from both the crankshaft position sensor and the mass air
flow sensor.
Various Fuel Injection Increase/Decrease CompensationNBEC0014S03In addition, the amount of fuel injected is compensated to improve engine performance under various oper-
ating conditions as listed below.

IDuring warm-up
IWhen starting the engine
IDuring acceleration
IHot-engine operation
IWhen selector lever is changed from ªNº to ªDº
IHigh-load, high-speed operation

IDuring deceleration
IDuring high engine speed operation
ENGINE AND EMISSION BASIC CONTROL SYSTEM DESCRIPTION
Multiport Fuel Injection (MFI) System
EC-28

Mixture Ratio Feedback Control (Closed loop control)NBEC0014S04
SEF336WA
The mixture ratio feedback system provides the best air-fuel mixture ratio for driveability and emission con-
trol. The warm-up three way catalyst can then better reduce CO, HC and NOx emissions. This system uses
a heated oxygen sensor 1 (front) 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 the
heated oxygen sensor 1 (front), refer to EC-192. This maintains the mixture ratio within the range of stoichio-
metric (ideal air-fuel mixture).
This stage is referred to as the closed loop control condition.
Heated oxygen sensor 2 (rear) is located downstream of the warm-up three way catalyst. Even if the switch-
ing characteristics of the heated oxygen sensor 1 (front) shift, the air-fuel ratio is controlled to stoichiometric
by the signal from the heated oxygen sensor 2 (rear).
Open Loop ControlNBEC0014S05The 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.
IDeceleration and acceleration
IHigh-load, high-speed operation
IMalfunction of heated oxygen sensor 1 (front) or its circuit
IInsufficient activation of heated oxygen sensor 1 (front) at low engine coolant temperature
IHigh engine coolant temperature
IDuring warm-up
IAfter shifting from ªNº to ªDº
IWhen starting the engine
Mixture Ratio Self-learning ControlNBEC0014S06The mixture ratio feedback control system monitors the mixture ratio signal transmitted from the heated oxy-
gen sensor 1 (front). 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 con-
trolled as originally designed. Both manufacturing differences (i.e., mass air flow sensor hot wire) and char-
acteristic 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 ªinjection pulse durationº to automatically compensate for the difference between
the two ratios.
ªFuel trimº refers to the feedback compensation value compared against the basic injection duration. Fuel trim
includes short term fuel trim and long term fuel trim.
ªShort term fuel trimº is the short-term fuel compensation used to maintain the mixture ratio at its theoretical
value. The signal from the heated oxygen sensor 1 (front) 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.
ªLong term fuel trimº 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.
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ENGINE AND EMISSION BASIC CONTROL SYSTEM DESCRIPTION
Multiport Fuel Injection (MFI) System (Cont'd)
EC-29