2004 INFINITI FX35 control

EC-680
[VK45DE]
ENGINE CONTROL SYSTEM
Revision: 2004 November 2004 FX35/FX45
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 whether 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-863
. 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

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-
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.
PBIB0121E

ENGINE CONTROL SYSTEM
EC-681
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Revision: 2004 November 2004 FX35/FX45
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 eight cylinders twice each engine cycle. In other words, pulse signals of
the same width are simultaneously transmitted from the ECM.
The eight 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) SystemABS00BZ7
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.
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
PBIB0122E
Sensor Input signal to ECM ECM function Actuator
Crankshaft position sensor (POS)
Engine speed*
2
Piston position
Ignition timing
controlPower 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
Knock sensor Engine knocking
Park/neutral position (PNP) switch Gear position
Battery
Battery voltage*
2
Wheel sensor*1Vehicle speed
SEF742M

EC-682
[VK45DE]
ENGINE CONTROL SYSTEM
Revision: 2004 November 2004 FX35/FX45

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.
Nissan Torque Demand (NTD) Control SystemABS00BZ8
INPUT/OUTPUT SIGNAL CHART
*: This signal is sent to the ECM through CAN communication line.
SYSTEM DESCRIPTION
NTD control system decides the target traction based on the accelerator operation status and the current driv-
ing condition. It then selects the engine torque target by correcting running resistance and atmospheric pres-
sure, and controlling the power-train. Using electric throttle control actuator, it achieves the engine torque
development target which corresponds linearly to the driver's accelerator operation.
Running resistance correction control compares the engine torque estimate value, measured vehicle acceler-
ation, and running resistance on a flat road, and estimates vehicle weight gain and running resistance varia-
tion caused by slopes to correct the engine torque estimate value.
Atmospheric pressure correction control compares the engine torque estimate value from the airflow rate and
the target engine torque for the target traction, and estimates variation of atmospheric pressure to correct the
target engine torque. This system achieves powerful driving without reducing engine performance in the prac-
tical speed range in mountains and high-altitude areas.
Sensor Input signal to ECM ECM function Actuator
Camshaft position sensor (PHASE)
Crankshaft position sensor (POS)Engine speed
NTD controlElectric throttle con-
trol actuator and fuel
injector 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
Park/Neutral position (PNP) switch Gear position
Power steering pressure sensor Power steering operation
Battery Battery voltage
TCM (CAN communication) A/T control signal
Air conditioner switch* Air conditioner operation
ABS actuator and electric unit (control unit)* VDC/TCS/ABS operation
Wheel sensor* Vehicle speed
Electrical load* Electrical load signal

ENGINE CONTROL SYSTEM
EC-683
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Revision: 2004 November 2004 FX35/FX45
Air Conditioning Cut ControlABS00BZ9
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.
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.
Fuel Cut Control (at No Load and High Engine Speed)ABS00BZA
INPUT/OUTPUT SIGNAL CHART
*: This signal is sent to the ECM through CAN communication line.
SYSTEM DESCRIPTION
If the engine speed is above 1,400 rpm under no load (for example, the shift position is neutral and engine
speed is over 1,400 rpm) fuel will be cut off after some time. The exact time when the fuel is cut off varies
based on engine speed.
Fuel cut will be operated until the engine speed reaches 1,000 rpm, then fuel cut will be cancelled.
NOTE:
This function is different from deceleration control listed under Multiport Fuel Injection (MFI) System, EC-679
.
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 position
Accelerator pedal position sensor Accelerator pedal position
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
Wheel sensor*
1Vehicle speed
Sensor Input signal to ECM ECM function Actuator
Park/neutral position (PNP) switch Neutral position
Fuel cut control Fuel injector Accelerator pedal position sensor Accelerator pedal position
Engine coolant temperature sensor Engine coolant temperature
Crankshaft position sensor (POS)
Camshaft position sensor (PHASE)Engine speed
Wheel sensor* Vehicle speed

EC-684
[VK45DE]
ENGINE CONTROL SYSTEM
Revision: 2004 November 2004 FX35/FX45
CAN communicationABS00BZB
SYSTEM DESCRIPTION
CAN (Controller Area Network) is a serial communication line for real time application. It is an on-vehicle mul-
tiplex communication line with high data communication speed and excellent error detection ability. Many elec-
tronic control units are equipped onto a vehicle, and each control unit shares information and links with other
control units during operation (not independent). In CAN communication, control units are connected with 2
communication lines (CAN H line, CAN L line) allowing a high rate of information transmission with less wiring.
Each control unit transmits/receives data but selectively reads required data only.
Refer to LAN-6, "
CAN Communication Unit" , about CAN communication for detail.

EC-698
[VK45DE]
BASIC SERVICE PROCEDURE
Revision: 2004 November 2004 FX35/FX45
35. ERASE UNNECESSARY DTC
After this inspection, unnecessary DTC might be displayed.
Erase the stored memory in ECM and TCM. Refer to EC-715, "
HOW TO ERASE EMISSION-RELATED DIAG-
NOSTIC INFORMATION" and AT- 3 9 , "HOW TO ERASE DTC" .
>> GO TO 4.
36. CHECK ECM FUNCTION
1. Substitute another known-good ECM to check ECM function. (ECM may be the cause of an incident, but
this is a rare case.)
2. Perform initialization of IVIS (NATS) system and registration of all IVIS (NATS) ignition key IDs. Refer
toBL-208, "
ECM Re-communicating Function" .
>> GO TO 4.
Accelerator Pedal Released Position LearningABS00BZE
DESCRIPTION
Accelerator Pedal Released Position Learning is an operation to learn the fully released position of the accel-
erator pedal by monitoring the accelerator pedal position sensor output signal. It must be performed each time
harness connector of accelerator pedal position sensor or ECM is disconnected.
OPERATION PROCEDURE
1. Make sure that accelerator pedal is fully released.
2. Turn ignition switch ON and wait at least 2 seconds.
3. Turn ignition switch OFF wait at least 10 seconds.
4. Turn ignition switch ON and wait at least 2 seconds.
5. Turn ignition switch OFF wait at least 10 seconds.
Throttle Valve Closed Position LearningABS00BZF
DESCRIPTION
Throttle Valve Closed Position Learning is an operation to learn the fully closed position of the throttle valve by
monitoring the throttle position sensor output signal. It must be performed each time harness connector of
electric throttle control actuator or ECM is disconnected.
OPERATION PROCEDURE
1. Make sure that accelerator pedal is fully released.
2. Turn ignition switch ON.
3. Turn ignition switch OFF wait at least 10 seconds.
Make sure that throttle valve moves during above 10 seconds by confirming the operating sound.
Idle Air Volume LearningABS00BZG
DESCRIPTION
Idle Air Volume Learning is an operation to learn the idle air volume that keeps each engine within the specific
range. It must be performed under any of the following conditions:

Each time electric throttle control actuator or ECM is replaced.

Idle speed or ignition timing is out of specification.
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 - 100°C (158 - 212°F)

PNP switch: ON

Electric load switch: OFF
(Air conditioner, headlamp, rear window defogger)

ON BOARD DIAGNOSTIC (OBD) SYSTEM
EC-703
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Revision: 2004 November 2004 FX35/FX45
ON BOARD DIAGNOSTIC (OBD) SYSTEMPFP:00028
IntroductionABS00BZI
The ECM has an on board diagnostic system, which detects malfunctions related to engine sensors or actua-
tors. The ECM also records various emission-related diagnostic information including:
The above information can be checked using procedures listed in the table below.
×: Applicable —: Not applicable
*: When DTC and 1st trip DTC simultaneously appear on the display, they cannot be clearly distinguished from each other.
The malfunction indicator lamp (MIL) on the instrument panel lights up when the same malfunction is detected
in two consecutive trips (Two trip detection logic), or when the ECM enters fail-safe mode. (Refer to EC-731
.)
Two Trip Detection LogicABS00BZJ
When a malfunction is detected for the first time, 1st trip DTC and 1st trip Freeze Frame data are stored in the
ECM memory. The MIL will not light up at this stage. <1st trip>
If the same malfunction is detected again during the next drive, the DTC and Freeze Frame data are stored in
the ECM memory, and the MIL lights up. The MIL lights up at the same time when the DTC is stored. <2nd
trip> The “trip” in the “Two Trip Detection Logic” means a driving mode in which self-diagnosis is performed
during vehicle operation. Specific on board diagnostic items will cause the ECM to light up or blink the MIL,
and store DTC and Freeze Frame data, even in the 1st trip, as shown below.
×: Applicable —: Not applicable
When there is an open circuit on MIL circuit, the ECM cannot warn the driver by lighting MIL up when there is
malfunction on engine control system.
Therefore, when electrical controlled throttle and part of ECM related diagnoses are continuously detected as
NG for 5 trips, ECM warns the driver that engine control system malfunctions and MIL circuit is open by means
of operating fail-safe function.
Emission-related diagnostic information SAE Mode
Diagnostic Trouble Code (DTC) Mode 3 of SAE J1979
Freeze Frame data Mode 2 of SAE J1979
System Readiness Test (SRT) code Mode 1 of SAE J1979
1st Trip Diagnostic Trouble Code (1st Trip DTC) Mode 7 of SAE J1979
1st Trip Freeze Frame data
Test values and Test limits Mode 6 of SAE J1979
Calibration ID Mode 9 of SAE J1979
DTC 1st trip DTCFreeze Frame
data1st trip Freeze
Frame dataSRT code Test value
CONSULT-II×× × × ×—
GST×× ×—××
ECM××*— ———
ItemsMIL DTC 1st trip DTC
1st trip 2nd trip
1st trip
displaying2nd trip
displaying1st trip
displaying2nd trip
display-
ing BlinkingLighting
upBlinkingLighting
up
Misfire (Possible three way cata-
lyst damage) — DTC: P0300 -
P0308 is being detected×———— —×—
Misfire (Possible three way cata-
lyst damage) — DTC: P0300 -
P0308 is being detected——×——×——
One trip detection diagnoses
(Refer to EC-662
.)—×——×———
Except above — — —×—××—

ON BOARD DIAGNOSTIC (OBD) SYSTEM
EC-705
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Revision: 2004 November 2004 FX35/FX45FUEL SYS-LEAN-B1 P0171 0171 — —×EC-914
FUEL SYS-RICH-B1 P0172 0172 — —×EC-923
FUEL SYS-LEAN-B2 P0174 0174 — —×EC-914
FUEL SYS-RICH-B2 P0175 0175 — —×EC-923
FTT SENSOR P0181 0181 — —×EC-931
FTT SEN/CIRCUIT P0182 0182 — —×EC-937
FTT SEN/CIRCUIT P0183 0183 — —×EC-937
TP SEN 1/CIRC P0222 0222 — — —EC-942
TP SEN 1/CIRC P0223 0223 — — —EC-942
MULTI CYL MISFIRE P0300 0300 — —×EC-949
CYL 1 MISFIRE P0301 0301 — —×EC-949
CYL 2 MISFIRE P0302 0302 — —×EC-949
CYL 3 MISFIRE P0303 0303 — —×EC-949
CYL 4 MISFIRE P0304 0304 — —×EC-949
CYL 5 MISFIRE P0305 0305 — —×EC-949
CYL 6 MISFIRE P0306 0306 — —×EC-949
CYL 7 MISFIRE P0307 0307 — —×EC-949
CYL 8 MISFIRE P0308 0308 — —×EC-949
KNOCK SEN/CIRC-B1 P0327 0327 — —×EC-955
KNOCK SEN/CIRC-B1 P0328 0328 — —×EC-955
KNOCK SEN/CIRC-B2 P0332 0332 — —×EC-955
KNOCK SEN/CIRC-B2 P0333 0333 — —×EC-955
CKP SEN/CIRCUIT P0335 0335 — —×EC-960
CMP SEN/CIRC-B1 P0340 0340 — —×EC-966
TW CATALYST SYS-B1 P0420 0420×××EC-971
TW CATALYST SYS-B2 P0430 0430×××EC-971
EVAP PURG FLOW/MON P0441 0441×××EC-976
EVAP SMALL LEAK P0442 0442×××EC-981
PURG VOLUME CONT/V P0444 0444 — —×EC-990
PURG VOLUME CONT/V P0445 0445 — —×EC-990
VENT CONTROL VALVE P0447 0447 — —×EC-997
EVAP SYS PRES SEN P0451 0451 — —×EC-1004
EVAP SYS PRES SEN P0452 0452 — —×EC-1007
EVAP SYS PRES SEN P0453 0453 — —×EC-1014
EVAP GROSS LEAK P0455 0455 —××EC-1022
EVAP VERY SML LEAK P0456 0456
×*5××EC-1030
FUEL LEV SEN SLOSH P0460 0460 — —×EC-1040
FUEL LEVEL SENSOR P0461 0461 — —×EC-1042
FUEL LEVL SEN/CIRC P0462 0462 — —×EC-1044
FUEL LEVL SEN/CIRC P0463 0463 — —×EC-1044
VEH SPEED SEN/CIRC*6P0500 0500 — —×EC-1046
ISC SYSTEM P0506 0506 — —×EC-1048
Items
(CONSULT-II screen terms)DTC*
1
SRT codeTest value/
Test limit
(GST only)1st trip DTCReference
page CONSULT-II
GST*
2ECM*3