2004 INFINITI FX35 oxygen

ENGINE CONTROL SYSTEM
EC-31
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Revision: 2004 November 2004 FX35/FX45
System ChartABS006K6
*1: This sensor is not used to control the engine system. This is used only for the on board diagnosis.
*2: This sensor is not used to control the engine system under normal conditions.
*3: This input signal is sent to the ECM through CAN communication line.
*4: This output signal is sent from the ECM through CAN communication line.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

Stop lamp switch

ICC steering switch

ICC brake switch

ASCD steering switch

ASCD brake switch

Fuel level sensor*1 *3

EVAP control system pressure sensor

Fuel tank temperature sensor*1

Heated oxygen sensor 2*2

TCM (Transmission control module)*3

ABS actuator and electric unit (control unit)*3

ICC unit*3

Air conditioner switch*3

Wheel sensor*3

Electrical load signal*3
Fuel injection & mixture ratio control Fuel injector
Electronic ignition system Power transistor
Fuel pump control Fuel pump relay
ICC vehicle speed control Electric throttle control actuator
ASCD vehicle speed control Electric throttle control actuator
On board diagnostic system
MIL (On the instrument panel)*
4
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*
4
Cooling fan control
Cooling fan relay*4
ON BOARD DIAGNOSIS for EVAP system EVAP canister vent control valve

EC-32
[VQ35DE]
ENGINE CONTROL SYSTEM
Revision: 2004 November 2004 FX35/FX45
Multiport Fuel Injection (MFI) SystemABS006K7
INPUT/OUTPUT SIGNAL CHART
*1: This sensor is not used to control the engine system under normal conditions.
*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
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 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

High-load, high-speed operation


During deceleration

During high engine speed operation
Sensor Input Signal to ECM ECM function Actuator
Crankshaft position sensor (POS)
Engine speed*
3
Piston position
Fuel injection
& mixture ratio
controlFuel injector 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
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
Air conditioner switch*
2Air conditioner operation
Wheel sensor*
2Vehicle speed

ENGINE CONTROL SYSTEM
EC-33
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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 1 can then better reduce CO, HC and NOx emissions. This system uses heated oxy-
gen 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-205
. 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 1. Even if the switching characteris-
tics 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 wire) 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

BASIC SERVICE PROCEDURE
EC-45
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Revision: 2004 November 2004 FX35/FX45
19. CHECK HEATED OXYGEN SENSOR 1 (BANK 1) SIGNAL
With CONSULT-II
1. Run engine at about 2,000 rpm for about 2 minutes under no-load.
2. See “HO2S1 MNTR (B1)” in “DATA MONITOR” mode.
3. Running engine at 2,000 rpm under no-load (The engine is
warmed up to normal operating temperature.), check that the
monitor fluctuates between LEAN and RICH more than 5 times
during 10 seconds.
OK or NG
OK >> GO TO 21.
NG (Monitor does not fluctuate.)>>GO TO 23.
NG (Monitor fluctuates less than 5 times.)>>GO TO 31.
20. CHECK HEATED OXYGEN SENSOR 1 (BANK 1) SIGNAL
Without CONSULT-II
1. Stop engine and set ECM to Self-diagnostic mode II (Heated oxygen sensor 1 monitor). Refer to EC-70,
"HOW TO SWITCH DIAGNOSTIC TEST MODE" .
2. Start engine and run it at about 2,000 rpm for about 2 minutes under no-load.
3. Running engine at 2,000 rpm under no-load (The engine is warmed up to normal operating temperature.),
check that the MIL comes on more than 5 times during 10 seconds.
OK or NG
OK >> GO TO 22.
NG (MIL does not come on)>>GO TO 23.
NG (MIL comes on less than 5 times)>>GO TO 31.
21. CHECK HEATED OXYGEN SENSOR 1 (BANK 2) SIGNAL
With CONSULT-II
1. See “HO2S1 MNTR (B2)” in “DATA MONITOR” mode.
2. Running engine at 2,000 rpm under no-load (The engine is
warmed up to normal operating temperature.), check that the
monitor fluctuates between LEAN and RICH more than 5 times
during 10 seconds.
OK or NG
OK >>INSPECTION END
NG (Monitor does not fluctuate.)>>GO TO 24.
NG (Monitor fluctuates less than 5 times.)>>GO TO 31.1 time: RICH → LEAN → RICH
2 times: RICH → LEAN → RICH → LEAN → RICH
PBIB0120E
1 time: RICH → LEAN → RICH
2 times: RICH → LEAN → RICH → LEAN → RICH
PBIB0120E

EC-46
[VQ35DE]
BASIC SERVICE PROCEDURE
Revision: 2004 November 2004 FX35/FX45
22. CHECK HEATED OXYGEN SENSOR 1 (BANK 2) SIGNAL
Without CONSULT-II
1. Switch the monitored sensor from bank 1 to bank 2. Refer to EC-70, "
How to Switch Monitored Sensor
From Bank 1 to Bank 2 or Vice Versa" .
2. Running engine at 2,000 rpm under no-load (The engine is warmed up to normal operating temperature.),
check that the MIL comes on more than 5 times during 10 seconds.
OK or NG
OK >>INSPECTION END
NG (MIL does not come on)>>GO TO 24.
NG (MIL comes on less than 5 times)>>GO TO 31.
23. CHECK HEATED OXYGEN SENSOR 1 (BANK 1) HARNESS
1. Turn ignition switch OFF and disconnect battery ground cable.
2. Disconnect ECM harness connector.
3. Disconnect heated oxygen sensor 1 (bank 1) harness connector.
4. Check harness continuity between ECM terminal 35 and heated oxygen sensor 1 (bank 1) terminal 1.
Refer to Wiring Diagram, EC-207, "
BANK 1" .
5. Also check harness for short to ground and short to power.
OK or NG
OK >> GO TO 25.
NG >> 1. Repair or replace harness between ECM and heated oxygen sensor 1 (bank 1).
2. GO TO 4.
24. CHECK HEATED OXYGEN SENSOR 1 (BANK 2) HARNESS
1. Turn ignition switch OFF and disconnect battery ground cable.
2. Disconnect ECM harness connector.
3. Disconnect heated oxygen sensor 1 (bank 2) harness connector.
4. Check harness continuity between ECM terminal 16 and heated oxygen sensor 1 (bank 2) terminal 1.
Refer to Wiring Diagram, EC-209, "
BANK 2" .
5. Also check harness for short to ground and short to power.
OK or NG
OK >> GO TO 25.
NG >> 1. Repair or replace harness between ECM and heated oxygen sensor 1 (bank 2).
2. GO TO 4.
25. PERFORM ACCELERATOR PEDAL RELEASED POSITION LEARNING
1. Reconnect ECM harness connector.
2. Perform EC-49, "
Accelerator Pedal Released Position Learning" .
>> GO TO 26.
26. PERFORM THROTTLE VALVE CLOSED POSITION LEARNING
Perform EC-49, "
Throttle Valve Closed Position Learning" .
>> GO TO 27.
Continuity should exist.
Continuity should exist.

BASIC SERVICE PROCEDURE
EC-47
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Revision: 2004 November 2004 FX35/FX45
27. PERFORM IDLE AIR VOLUME LEARNING
Refer to EC-49, "
Idle Air Volume Learning" .
Is Idle Air Volume Learning carried out successfully?
Ye s o r N o
Yes (With CONSULT-II)>>GO TO 28.
Yes (Without CONSULT-II)>>GO TO 29.
No >> 1. Follow the instruction of Idle Air Volume Learning.
2. GO TO 4.
28. CHECK CO%
With CONSULT-II
1. Start engine and warm it up until engine coolant temperature indicator points the middle of gauge.
2. Turn ignition switch OFF, wait at least 10 seconds and then turn ON.
3. Select “ENG COOLANT TEMP” in “ACTIVE TEST” mode.
4. Set “ENG COOLANT TEMP” to 5°C (41°F) by touching “DWN”
and “Qd”.
5. Start engine and rev it (2,000 to 3,000 rpm) two or three times
under no-load, then run engine at idle speed.
6. Check CO%.
OK or NG
OK >> GO TO 31.
NG >> GO TO 30.
29. CHECK CO%
Without CONSULT-II
1. Start engine and warm it up until engine coolant temperature indicator points to the middle of gauge.
2. Turn ignition switch OFF.
3. Disconnect engine coolant temperature sensor harness connector.
4. Connect a resistor (4.4 kΩ) between terminals of engine coolant
temperature sensor harness connector.
5. Start engine and rev it (2,000 to 3,000 rpm) two or three times
under no-load, then run engine at idle speed.
6. Check CO%.
7. After checking CO%, turn ignition switch OFF, disconnect the
resistor from the terminals of engine coolant temperature sensor
harness connector, and then connect engine coolant tempera-
ture sensor harness connector to engine coolant temperature
sensor.
OK or NG
OK >> GO TO 31.
NG >> GO TO 30.
30. RECONNECT HEATED OXYGEN SENSOR 1 HARNESS CONNECTOR
1. Turn ignition switch OFF.
2. Reconnect heated oxygen sensor 1 harness connector.
>> GO TO 34. Idle CO: 0.7 − 9.9% and engine runs smoothly.
SEF172Y
Idle CO: 0.7 − 9.9% and engine runs smoothly.
SEF982UA

EC-48
[VQ35DE]
BASIC SERVICE PROCEDURE
Revision: 2004 November 2004 FX35/FX45
31. REPLACE HEATED OXYGEN SENSOR 1
1. Stop engine.
2. Replace heated oxygen sensor 1 on the malfunctioning bank.
With CONSULT-II>>GO TO 32.
Without CONSULT-II>>GO TO 33.
32. CHECK HEATED OXYGEN SENSOR 1 (BANK 1)/(BANK 2) SIGNAL
With CONSULT-II
1. Start engine and warm it up until engine coolant temperature indicator points the middle of gauge.
2. See “HO2S1 MNTR (B1)/(B2)” in “DATA MONITOR” mode.
3. Running engine at 2,000 rpm under no-load (The engine is
warmed up to normal operating temperature.), check that the
monitor fluctuates between LEAN and RICH more than 5 times
during 10 seconds.
OK or NG
OK >> GO TO 4.
NG >> GO TO 34.
33. CHECK HEATED OXYGEN SENSOR 1 (BANK 1)/(BANK 2) SIGNAL
Without CONSULT-II
1. Set ECM to Self-diagnostic mode II (Heated oxygen sensor 1 monitor). Refer to EC-70, "
HOW TO
SWITCH DIAGNOSTIC TEST MODE" .
2. Switch the monitored sensor to the malfunctioning bank. Refer to EC-70, "
How to Switch Monitored Sen-
sor From Bank 1 to Bank 2 or Vice Versa" .
3. Running engine at 2,000 rpm under no-load (The engine is warmed up to normal operating temperature.),
check that the MIL comes on more than 5 times during 10 seconds.
OK or NG
OK >> GO TO 4.
NG >> GO TO 34.
34. DETECT MALFUNCTIONING PART
Check the following.

Check fuel pressure regulator and repair or replace if necessary. Refer to EC-51, "Fuel Pressure Check" .

Check mass air flow sensor and its circuit, and repair or replace if necessary. Refer to EC-165 and EC-
173 .

Check injector and its circuit, and repair or replace if necessary. Refer to EC-597 .

Check engine coolant temperature sensor and its circuit, and repair or replace if necessary. Refer to EC-
185 and EC-197 .
OK or NG
OK >> GO TO 36.
NG >> 1. Repair or replace.
2. GO TO 35. 1 time: RICH → LEAN → RICH
2 times: RICH → LEAN → RICH → LEAN → RICH
PBIB0120E

EC-60
[VQ35DE]
ON BOARD DIAGNOSTIC (OBD) SYSTEM
Revision: 2004 November 2004 FX35/FX45
SRT Item
The table below shows required self-diagnostic items to set the SRT to “CMPLT”.
*1: If completion of several SRTs is required, perform driving patterns (DTC confirmation procedure), one by one based on the priority for
models with CONSULT-II.
SRT Set Timing
SRT is set as “CMPLT” after self-diagnosis has been performed one or more times. Completion of SRT is
done regardless of whether the result is OK or NG. The set timing is different between OK and NG results and
is shown in the table below.
OK: Self-diagnosis is carried out and the result is OK.
NG: Self-diagnosis is carried out and the result is NG.
—: Self-diagnosis is not carried out.
When all SRT related self-diagnoses showed OK results in a single cycle (Ignition OFF-ON-OFF), the SRT will
indicate “CMPLT”. → Case 1 above
SRT item
(CONSULT-II indica-
tion)Perfor-
mance Pri-
ority*1Required self-diagnostic items to set the SRT to “CMPLT”Corresponding DTC
No.
CATALYST 2 Three way catalyst function P0420, P0430
EVAP SYSTEM 1 EVAP control system P0442
2 EVAP control system P0456
2 EVAP control system purge flow monitoring P0441
HO2S 2Heated oxygen sensor 1 P0133, P0153
Heated oxygen sensor 1 P1143, P1163
Heated oxygen sensor 1 P1144, P1164
Heated oxygen sensor 2 P0139, P0159
Heated oxygen sensor 2 P1146, P1166
Heated oxygen sensor 2 P1147, P1167
HO2S HTR 2 Heated oxygen sensor 1 heater P0031, P0032, P0051,
P0052
Heated oxygen sensor 2 heater P0037, P0038, P0057,
P0058
Self-diagnosis resultExample
DiagnosisIgnition cycle
← ON → OFF ← ON → OFF ← ON → OFF ← ON →
All OK Case 1 P0400 OK (1) — (1) OK (2) — (2)
P0402 OK (1) — (1) — (1) OK (2)
P1402 OK (1) OK (2) — (2) — (2)
SRT of EGR “CMPLT” “CMPLT” “CMPLT” “CMPLT”
Case 2 P0400 OK (1) — (1) — (1) — (1)
P0402 — (0) — (0) OK (1) — (1)
P1402 OK (1) OK (2) — (2) — (2)
SRT of EGR “INCMP” “INCMP” “CMPLT” “CMPLT”
NG exists Case 3 P0400 OK OK — —
P0402 — — — —
P1402 NG — NGNG
(Consecutive
NG)
(1st trip)
DTC1st trip DTC — 1st trip DTCDTC
(= MIL ON)
SRT of EGR “INCMP” “INCMP” “INCMP” “CMPLT”