engine coolant INFINITI FX35 2007 Owners Manual
[x] Cancel search | Manufacturer: INFINITI, Model Year: 2007, Model line: FX35, Model: INFINITI FX35 2007Pages: 4366, PDF Size: 55.42 MB
Page 1873 of 4366
![INFINITI FX35 2007 Owners Manual DTC P1217 ENGINE OVER TEMPERATURE EC-497
[VQ35DE]
C
D E
F
G H
I
J
K L
M A
EC
Revision: 2006 July 2007 FX35/FX45
Cooling Fan Relay Operation
The ECM controls cooling fan relays in the IPDM INFINITI FX35 2007 Owners Manual DTC P1217 ENGINE OVER TEMPERATURE EC-497
[VQ35DE]
C
D E
F
G H
I
J
K L
M A
EC
Revision: 2006 July 2007 FX35/FX45
Cooling Fan Relay Operation
The ECM controls cooling fan relays in the IPDM](/img/42/57018/w960_57018-1872.png)
DTC P1217 ENGINE OVER TEMPERATURE EC-497
[VQ35DE]
C
D E
F
G H
I
J
K L
M A
EC
Revision: 2006 July 2007 FX35/FX45
Cooling Fan Relay Operation
The ECM controls cooling fan relays in the IPDM E/R through CAN communication line.
COMPONENT DESCRIPTION
Cooling Fan Motor
The cooling fan operates at each speed when the current flows in the cooling fan motor as follows.
The cooling fan operates at low (LOW) speed when cooling fan motors-1 and -2 are circuited in series under
middle speed condition.
CONSULT-II Reference Value in Data Monitor ModeNBS003UI
Specification data are reference values.
On Board Diagnosis LogicNBS003UJ
If the cooling fan or another component in the cooling system malfunctions, engine coolant temperature will
rise.
When the engine coolant temperature reaches an abnormally high temperature condition, a malfunction is
indicated.
This self-diagnosis has the one trip detection logic.
Cooling fan speed Cooling fan relay
123
Stop (OFF) OFF OFF OFF
Low (LOW) OFF ON OFF
Middle (MID) OFF OFF ON
High (HI) ON OFF ON
Cooling fan speed Cooling fan motor terminals
(+) ( −)
Middle (MID) 1 3 and 4
2 3 and 4
1 and 2 3
1 and 2 4
High (HI) 1 and 2 3 and 4
MONITOR ITEM CONDITION SPECIFICATION
AIR COND SIG
Engine: After warming up, idle
the engine Air conditioner switch: OFF OFF
Air conditioner switch: ON
(Compressor operates.) ON
COOLING FAN
Engine: After warming up, idle
the engine
Air conditioner switch: OFF Engine coolant temperature is 97
°C
(207 °F) or less OFF
Engine coolant temperature is
between 98 °C (208 °F) and 99 °C
(210 °F) LOW
Engine coolant temperature is
between 100 °C (212 °F) and 104 °C
(219 °F) MID
Engine coolant temperature is 105 °C
(221 °F) or more HI
Page 1874 of 4366
![INFINITI FX35 2007 Owners Manual EC-498
[VQ35DE]
DTC P1217 ENGINE OVER TEMPERATURE
Revision: 2006 July 2007 FX35/FX45
CAUTION:
When a malfunction is indicated, be sure to replace the coolant. Refer to CO-11, "
Changing Engine
Cool INFINITI FX35 2007 Owners Manual EC-498
[VQ35DE]
DTC P1217 ENGINE OVER TEMPERATURE
Revision: 2006 July 2007 FX35/FX45
CAUTION:
When a malfunction is indicated, be sure to replace the coolant. Refer to CO-11, "
Changing Engine
Cool](/img/42/57018/w960_57018-1873.png)
EC-498
[VQ35DE]
DTC P1217 ENGINE OVER TEMPERATURE
Revision: 2006 July 2007 FX35/FX45
CAUTION:
When a malfunction is indicated, be sure to replace the coolant. Refer to CO-11, "
Changing Engine
Coolant" . Also, replace the engine oil. Refer to LU-9, "Changing Engine Oil" .
1. Fill radiator with coolant up to specified level with a filling speed of 2 liters per minute. Be sure to use coolant with the proper mixture ratio. Refer to MA-13, "
Anti-Freeze Coolant Mixture Ratio" .
2. After refilling coolant, run engine to ensure that no water-flow noise is emitted.
Overall Function CheckNBS003UK
Use this procedure to check the overall function of the cooling fan. During this check, a DTC might not be con-
firmed.
WARNING:
Never remove the radiator cap when the engine is hot. Serious burns could be caused by high pres-
sure fluid escaping from the radiator.
Wrap a thick cloth around cap. Carefully remove the cap by turning it a quarter turn to allow built-up
pressure to escape. Then turn the cap all the way off.
WITH CONSULT-II
1. Check the coolant level in the reservoir tank and radiator. Allow engine to cool before checking coolant level.
If the coolant level in the reservoir tank and/or radiator is below
the proper range, skip the following steps and go to EC-502,
"PROCEDURE A" .
2. Confirm whether customer filled the coolant or not. If customer filled the coolant, skip the following steps and go to EC-502,
"PROCEDURE A" .
3. Turn ignition switch ON.
4. Perform “COOLING FAN” in “ACTIVE TEST” mode with CON- SULT-II.
5. If the results are NG, go to EC-504, "
PROCEDURE B" .
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P1217
1217 Engine over tempera-
ture (Overheat)
Cooling fan does not operate properly (Over-
heat).
Cooling fan system does not operate prop-
erly (Overheat).
Engine coolant level was not added to the
system using the proper filling method.
Engine coolant is not within the specified
range.
Harness or connectors
(Cooling fan circuit is open or shorted.)
IPDM E/R
Cooling fan
Radiator hose
Radiator
Radiator cap
Water pump
Thermostat
For more information, refer to EC-507,
"Main 12 Causes of Overheating" .
SEF621W
SEF646X
Page 1875 of 4366
![INFINITI FX35 2007 Owners Manual DTC P1217 ENGINE OVER TEMPERATURE EC-499
[VQ35DE]
C
D E
F
G H
I
J
K L
M A
EC
Revision: 2006 July 2007 FX35/FX45
WITH GST
1. Check the coolant level in the reservoir tank and radiator.
A INFINITI FX35 2007 Owners Manual DTC P1217 ENGINE OVER TEMPERATURE EC-499
[VQ35DE]
C
D E
F
G H
I
J
K L
M A
EC
Revision: 2006 July 2007 FX35/FX45
WITH GST
1. Check the coolant level in the reservoir tank and radiator.
A](/img/42/57018/w960_57018-1874.png)
DTC P1217 ENGINE OVER TEMPERATURE EC-499
[VQ35DE]
C
D E
F
G H
I
J
K L
M A
EC
Revision: 2006 July 2007 FX35/FX45
WITH GST
1. Check the coolant level in the reservoir tank and radiator.
Allow engine to cool before checking coolant level.
If the coolant level in the reservoir tank and/or radiator is below
the proper range, skip the following steps and go to EC-502,
"PROCEDURE A" .
2. Confirm whether customer filled the coolant or not. If customer filled the coolant, skip the following steps and go to EC-502,
"PROCEDURE A" .
3. Perform IPDM E/R auto active test and check cooling fan motors operation, refer to PG-21, "
Auto Active Test"
4. If NG, go to EC-504, "PROCEDURE B" .SEF621W
Page 1879 of 4366
![INFINITI FX35 2007 Owners Manual DTC P1217 ENGINE OVER TEMPERATURE EC-503
[VQ35DE]
C
D E
F
G H
I
J
K L
M A
EC
Revision: 2006 July 2007 FX35/FX45
6. CHECK THERMOSTAT
Refer to CO-27, "
WATER INLET AND THERMOSTAT ASSEMBL INFINITI FX35 2007 Owners Manual DTC P1217 ENGINE OVER TEMPERATURE EC-503
[VQ35DE]
C
D E
F
G H
I
J
K L
M A
EC
Revision: 2006 July 2007 FX35/FX45
6. CHECK THERMOSTAT
Refer to CO-27, "
WATER INLET AND THERMOSTAT ASSEMBL](/img/42/57018/w960_57018-1878.png)
DTC P1217 ENGINE OVER TEMPERATURE EC-503
[VQ35DE]
C
D E
F
G H
I
J
K L
M A
EC
Revision: 2006 July 2007 FX35/FX45
6. CHECK THERMOSTAT
Refer to CO-27, "
WATER INLET AND THERMOSTAT ASSEMBLY" .
OK or NG
OK >> GO TO 7.
NG >> Replace thermostat
7. CHECK ENGINE COOLANT TEMPERATURE SENSOR
Refer to EC-213, "
Component Inspection" .
OK or NG
OK >> GO TO 8.
NG >> Replace engine coolant temperature sensor.
8. CHECK MAIN 12 CAUSES
If the cause cannot be isolated, go to EC-507, "
Main 12 Causes of Overheating" .
>> INSPECTION END
Page 1883 of 4366
![INFINITI FX35 2007 Owners Manual DTC P1217 ENGINE OVER TEMPERATURE EC-507
[VQ35DE]
C
D E
F
G H
I
J
K L
M A
EC
Revision: 2006 July 2007 FX35/FX45
Main 12 Causes of OverheatingNBS003UN
*1: Turn the ignition switch ON.
*2: INFINITI FX35 2007 Owners Manual DTC P1217 ENGINE OVER TEMPERATURE EC-507
[VQ35DE]
C
D E
F
G H
I
J
K L
M A
EC
Revision: 2006 July 2007 FX35/FX45
Main 12 Causes of OverheatingNBS003UN
*1: Turn the ignition switch ON.
*2:](/img/42/57018/w960_57018-1882.png)
DTC P1217 ENGINE OVER TEMPERATURE EC-507
[VQ35DE]
C
D E
F
G H
I
J
K L
M A
EC
Revision: 2006 July 2007 FX35/FX45
Main 12 Causes of OverheatingNBS003UN
*1: Turn the ignition switch ON.
*2: Engine running at 3,000 rpm for 10 minutes.
*3: Drive at 90 km/h (55 MPH) for 30 minutes and then let idle for 10 minutes.
*4: After 60 minutes of cool down time.
For more information, refer to CO-7, "
OVERHEATING CAUSE ANALYSIS" .
Component InspectionNBS003UO
COOLING FAN MOTORS-1 AND -2
1. Disconnect cooling fan motor harness connectors.
2. Supply cooling fan motor terminals with battery voltage and check operation.
Engine Step Inspection item Equipment Standard Reference page
OFF 1
Blocked radiator
Blocked condenser
Blocked radiator grille
Blocked bumper
Visual No blocking —
2
Coolant mixtureCoolant tester 50 - 50% coolant mixture MA-13, "Anti-Freeze
Coolant Mixture Ratio"
3Coolant levelVisual Coolant up to MAX level
in reservoir tank and radi-
ator filler neck CO-11, "Changing
Engine Coolant"
4Radiator capPressure tester 59 - 98 kPa
(0.6 - 1.0 kg/cm2 , 9 - 14
psi) (Limit) CO-15, "
Checking Radia-
tor Cap"
ON*25Coolant leaksVisual No leaks
CO-11, "LEAK CHECK"
ON*26ThermostatTouch the upper and
lower radiator hoses Both hoses should be hot
CO-27, "WATER INLET
AND THERMOSTAT
ASSEMBLY"
ON*17Cooling fanCONSULT-II Operating See trouble diagnosis for
DTC P1217 ( EC-496,
"DTC P1217 ENGINE
OVER TEMPERATURE"
).
OFF 8
Combustion gas leakColor checker chemical
tester 4 Gas analyzer Negative —
ON*
39Coolant temperature
gaugeVisual Gauge less than 3/4 when driving —
Coolant overflow to
reservoir tankVisual No overflow during driving and idling CO-11, "Changing
Engine Coolant"
OFF*410Coolant return from
reservoir tank to radia-
torVisual Should be initial level in reservoir tank CO-11, "Changing
Engine Coolant"
OFF 11Cylinder headStraight gauge feeler
gauge 0.1 mm (0.004 in) Maxi-
mum distortion (warping) EM-103, "Cylinder Head
Distortion"
12Cylinder block and pis-
tonsVisual No scuffing on cylinder walls or piston EM-123, "CYLINDER
BLOCK"
SEF734W
Page 1889 of 4366
![INFINITI FX35 2007 Owners Manual DTC P1421 COLD START CONTROL EC-513
[VQ35DE]
C
D E
F
G H
I
J
K L
M A
EC
Revision: 2006 July 2007 FX35/FX45
DTC P1421 COLD START CONTROLPFP:23710
DescriptionNBS006S9
ECM controls ignition INFINITI FX35 2007 Owners Manual DTC P1421 COLD START CONTROL EC-513
[VQ35DE]
C
D E
F
G H
I
J
K L
M A
EC
Revision: 2006 July 2007 FX35/FX45
DTC P1421 COLD START CONTROLPFP:23710
DescriptionNBS006S9
ECM controls ignition](/img/42/57018/w960_57018-1888.png)
DTC P1421 COLD START CONTROL EC-513
[VQ35DE]
C
D E
F
G H
I
J
K L
M A
EC
Revision: 2006 July 2007 FX35/FX45
DTC P1421 COLD START CONTROLPFP:23710
DescriptionNBS006S9
ECM controls ignition timing and engine idle speed when engine is started with prewarming up condition.
This control promotes the activation of three way catalyst by heating the catalyst and reduces emissions.
On Board Diagnosis LogicNBS006SA
DTC Confirmation ProcedureNBS006SB
NOTE:
If DTC Confirmation Procedure has been previously conducted, always turn ignition switch OFF and wait
at least 10 seconds before conducting the next test.
If DTC P1421 is displayed with other DTC, first perform the trouble diagnosis for other DTC.
TESTING CONDITION:
Before performing the following procedure, confirm that battery voltage is more than 11V at idle.
WITH CONSULT-II
1. Turn ignition switch OFF and wait at least 10 seconds.
2. Turn ignition switch ON.
3. Select “DATA MONITOR” mode with CONSULT-II.
4. Check that the “COOLAN TEMP/S” indication is between 4 °C
(39 °F) and 36 °C (97 °F).
If “COOLAN TEMP/S” indication is within the specified value, go
to the following step.
If “COOLANT TEMP/S” indication is out of the specified value,
cool engine down or warm engine up and go to step 1.
5. Start engine and let it idle for 5 minutes.
6. If 1st trip DTC is detected, go to EC-513, "
Diagnostic Procedure"
.
WITH GST
Follow the procedure “WITH CONSULT-II” above.
Diagnostic ProcedureNBS006SC
1. PERFORM IDLE AIR VOLUME LEARNING
Perform EC-83, "
Idle Air Volume Learning" .
Is Idle Air Volume Learning carried out successfully?
Ye s o r N o
Ye s > > G O T O 2 .
No >> Follow the instruction of Idle Air Volume Learning.
2. CHECK INTAKE SYSTEM
Check for the cause of intake air volume lacking. Refer to the following.
Crushed intake air passage
Intake air passage clogging
OK or NG
OK >> GO TO 3.
NG >> Repair or replace malfunctioning part
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P1421
1421 Cold start emission reduction
strategy monitoring ECM does not control ignition timing and engine
idle speed properly when engine is started with
prewarming up condition.
Lack of intake air volume
Fuel injection system
ECM
SEF174Y
Page 2051 of 4366
![INFINITI FX35 2007 Owners Manual SERVICE DATA AND SPECIFICATIONS (SDS) EC-675
[VQ35DE]
C
D E
F
G H
I
J
K L
M A
EC
Revision: 2006 July 2007 FX35/FX45
SERVICE DATA AND SPECIFICATIONS (SDS)PFP:00030
Fuel PressureNBS0040H
Id INFINITI FX35 2007 Owners Manual SERVICE DATA AND SPECIFICATIONS (SDS) EC-675
[VQ35DE]
C
D E
F
G H
I
J
K L
M A
EC
Revision: 2006 July 2007 FX35/FX45
SERVICE DATA AND SPECIFICATIONS (SDS)PFP:00030
Fuel PressureNBS0040H
Id](/img/42/57018/w960_57018-2050.png)
SERVICE DATA AND SPECIFICATIONS (SDS) EC-675
[VQ35DE]
C
D E
F
G H
I
J
K L
M A
EC
Revision: 2006 July 2007 FX35/FX45
SERVICE DATA AND SPECIFICATIONS (SDS)PFP:00030
Fuel PressureNBS0040H
Idle Speed and Ignition TimingNBS0040I
*1: Under the following conditions:
Air conditioner switch: OFF
Electric load: OFF (Lights, heater fan & rear window defogger)
Steering wheel: Kept in straight-ahead position
Calculated Load ValueNBS0040J
Mass Air Flow SensorNBS0040K
*: Engine is warmed up to normal operating temperature and running under no load.
Intake Air Temperature SensorNBS0040L
Engine Coolant Temperature SensorNBS0040M
Air Fuel Ratio (A/F) Sensor 1 HeaterNBS0040N
Heated Oxygen sensor 2 HeaterNBS0040O
Crankshaft Position Sensor (POS)NBS0040P
Refer to EC-366, "Component Inspection" .
Camshaft Position Sensor (PHASE)NBS0040Q
Refer to EC-375, "Component Inspection" .
Throttle Control MotorNBS0040R
Fuel pressure at idling kPa (kg/cm2 , psi) Approximately 350 (3.57, 51)
Target idle speed
No load*1 (in P or N position) 650
±50 rpm
Air conditioner: ON In P or N position 700 rpm or more
Ignition timing In P or N position 15 ° ± 5 ° BTDC
Calculated load value% (Using CONSULT-II or GST)
At idle 5 - 35
At 2,500 rpm 5 - 35
Supply voltageBattery voltage (11 - 14V)
Output voltage at idle 1.0 - 1.2V*
Mass air flow (Using CONSULT-II or GST) 2.0 - 6.0 g·m/sec at idle*
7.0 - 20.0 g·m/sec at 2,500 rpm*
Temperature °C ( °F) Resistance k Ω
25 (77) 1.800 - 2.200
Temperature °C ( °F) Resistance k Ω
20 (68) 2.1 - 2.9
50 (122) 0.68 - 1.00
90 (194) 0.236 - 0.260
Resistance [at 25°C (77 °F)] 2.3 - 4.3 Ω
Resistance [at 25°C (77 °F)] 3.4 - 4.4 Ω
Resistance [at 25°C (77 °F)] Approximately 1 - 15 Ω
Page 2066 of 4366
![INFINITI FX35 2007 Owners Manual EC-690
[VK45DE]
PREPARATION
Revision: 2006 July 2007 FX35/FX45
Commercial Service ToolsNBS004JN
Tool name
(Kent-Moore No.) Description
Leak detector
i.e.: (J-41416) Locating the EVAP leak
EVAP s INFINITI FX35 2007 Owners Manual EC-690
[VK45DE]
PREPARATION
Revision: 2006 July 2007 FX35/FX45
Commercial Service ToolsNBS004JN
Tool name
(Kent-Moore No.) Description
Leak detector
i.e.: (J-41416) Locating the EVAP leak
EVAP s](/img/42/57018/w960_57018-2065.png)
EC-690
[VK45DE]
PREPARATION
Revision: 2006 July 2007 FX35/FX45
Commercial Service ToolsNBS004JN
Tool name
(Kent-Moore No.) Description
Leak detector
i.e.: (J-41416) Locating the EVAP leak
EVAP service port
adapter
i.e.: (J-41413-OBD) Applying positive pressure through EVAP service
port
Fuel filler cap adapter
i.e.: (MLR-8382) Checking fuel tank vacuum relief valve opening
pressure
Socket wrench Removing and installing engine coolant temperature sensor
Oxygen sensor thread
cleaner
i.e.: (J-43897-18)
(J-43897-12) Reconditioning the exhaust system threads
before installing a new oxygen sensor. Use with
anti-seize lubricant shown below.
a: J-43897-18 18 mm diameter with pitch 1.5
mm for Zirconia Oxygen Sensor
b: J-43897-12 12 mm diameter with pitch 1.25
mm for Titania Oxygen Sensor
Anti-seize lubricant
i.e.: (Permatex
TM
133AR or equivalent
meeting MIL
specification MIL-A-
907) Lubricating oxygen sensor thread cleaning tool
when reconditioning exhaust system threads.
S-NT703
S-NT704
S-NT815
S-NT705
AEM488
S-NT779
Page 2068 of 4366
![INFINITI FX35 2007 Owners Manual EC-692
[VK45DE]
ENGINE CONTROL SYSTEM
Revision: 2006 July 2007 FX35/FX45
Multiport Fuel Injection (MFI) SystemNBS004JO
INPUT/OUTPUT SIGNAL CHART
*1: This sensor is not used to control the engine syste INFINITI FX35 2007 Owners Manual EC-692
[VK45DE]
ENGINE CONTROL SYSTEM
Revision: 2006 July 2007 FX35/FX45
Multiport Fuel Injection (MFI) SystemNBS004JO
INPUT/OUTPUT SIGNAL CHART
*1: This sensor is not used to control the engine syste](/img/42/57018/w960_57018-2067.png)
EC-692
[VK45DE]
ENGINE CONTROL SYSTEM
Revision: 2006 July 2007 FX35/FX45
Multiport Fuel Injection (MFI) SystemNBS004JO
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 the crankshaft position sensor (POS), 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
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
control Fuel injector
Camshaft position sensor (PHASE)
Mass air flow sensor Amount of intake air
Engine coolant temperature sensor Engine coolant temperature
Air fuel ratio (A/F) 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
Battery Battery voltage*
3
Knock sensor Engine knocking condition
Power steering pressure sensor Power steering operation
Heated oxygen sensor 2*
1Density of oxygen in exhaust gas
ABS actuator and electric unit (control unit) VDC/TCS operation command*
2
Air conditioner switch Air conditioner operation
Wheel sensor Vehicle speed*
2
Page 2069 of 4366
![INFINITI FX35 2007 Owners Manual ENGINE CONTROL SYSTEM EC-693
[VK45DE]
C
D E
F
G H
I
J
K L
M A
EC
Revision: 2006 July 2007 FX35/FX45
MIXTURE RATIO FEEDBACK CONTROL (CLOSED LOOP CONTROL)
The mixture ratio feedback system INFINITI FX35 2007 Owners Manual ENGINE CONTROL SYSTEM EC-693
[VK45DE]
C
D E
F
G H
I
J
K L
M A
EC
Revision: 2006 July 2007 FX35/FX45
MIXTURE RATIO FEEDBACK CONTROL (CLOSED LOOP CONTROL)
The mixture ratio feedback system](/img/42/57018/w960_57018-2068.png)
ENGINE CONTROL SYSTEM EC-693
[VK45DE]
C
D E
F
G H
I
J
K L
M A
EC
Revision: 2006 July 2007 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 A/F
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 A/F sensor 1, refer to
EC-901
. 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 A/F 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 A/F sensor 1 or its circuit
Insufficient activation of A/F 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 A/F sensor 1.
This feedback signal is then sent to the ECM. The ECM controls the basic mixture ratio as close to the theoret-
ical mixture ratio as possible. However, the basic mixture ratio is not necessarily controlled as originally
designed. Both manufacturing differences (i.e., mass air flow sensor hot wire) and characteristic changes dur-
ing operation (i.e., fuel 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 A/F sensor 1 indicates whether the mixture ratio is RICH or LEAN compared to the the-
oretical 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.
PBIB3020E