Infiniti FX35, FX50 (S51). Manual — part 625
MULTIPORT FUEL INJECTION SYSTEM
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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 over time to compensate for continual deviation
of the short-term fuel trim from the central value. Continual deviation will occur due to individual engine differ-
ences, wear over time and changes in the usage environment.
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 six cylinders twice each engine cycle. In other words, pulse signals of
the same width are simultaneously transmitted from the ECM.
The six injectors will then receive the signals 2 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, operation of the engine at excessively high speeds or oper-
ation of the vehicle at excessively high speeds.
SEF179U
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MULTIPORT FUEL INJECTION SYSTEM
Component Parts Location
INFOID:0000000005568460
1.
IPDM E/R
2.
Battery current sensor
3.
Cooling fan relay
4.
Mass air flow sensor (with intake air
temperature sensor) (bank 1)
5.
Refrigerant pressure sensor
6.
Cooling fan motor-2
7.
Intake valve timing control solenoid
valve
8.
Exhaust valve timing control magnet
retarder
9.
Cooling fan control module
10. Cooling fan motor-1
11.
Mass air flow sensor (with intake air
temperature sensor) (bank 2)
12. ICC brake hold relay (ICC models)
13. Ignition coil (with power transistor)
and spark plug (bank 2)
14. Electric throttle control actuator
(bank 2)
15. A/F sensor 1 (bank 2)
16. Fuel injector (bank 2)
17. Camshaft position sensor
18. Engine coolant temperature sensor
19. Knock sensor
20. Exhaust valve timing control position
sensor
21. EVAP canister purge volume control
solenoid valve
22. Fuel injector (bank 1)
23. Ignition coil (with power transistor)
and spark plug (bank 1)
24. EVAP service port
25. A/F sensor 1 (bank 1)
26. Crankshaft position sensor
27. Electric throttle control actuator
(bank 1)
JMBIA1496ZZ
MULTIPORT FUEL INJECTION SYSTEM
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1.
Mass air flow sensor (with intake air
temperature sensor) (bank 1)
2.
Mass air flow sensor (with intake air
temperature sensor) (bank 2)
1.
Electric throttle control actuator
(bank 1)
2.
Electric throttle control actuator
(bank 2)
1.
Cooling fan control module
2.
Cooling fan motor-1
3.
Cooling fan motor-2
4.
Cooling fan relay
JMBIA1497ZZ
JMBIA0004ZZ
JMBIA1498ZZ
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MULTIPORT FUEL INJECTION SYSTEM
JMBIA1683GB
1.
A/F sensor 1 (bank 2)
2.
Heated oxygen sensor 2 (bank 2)
3.
Heated oxygen sensor 2 (bank 2)
harness connector
4.
Heated oxygen sensor 2 (bank 1)
harness connector
5.
Heated oxygen sensor 2 (bank 1)
6.
A/F sensor 1 (bank 1)
: Vehicle front
1.
A/F sensor 1 (bank 1) harness con-
nector
2.
A/F sensor 1 (bank 2) harness con-
nector
: Vehicle front
JMBIA1499ZZ
JMBIA0006ZZ
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