Nissan Frontier. Manual - part 365

 

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Nissan Frontier. Manual - part 365

 

 

ENGINE CONTROL SYSTEM

EC-31

< SYSTEM DESCRIPTION >

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ALBIA0515ZZ

1.

EVAP canister vent control valve 
(view with bed removed)

2.

EVAP control system pressure 
sensor

3.

Drain filter

4.

EVAP canister

5.

Intake manifold collector
 (view with air cleaner case removed)

6.

Power steering pressure sensor

7.

Brake pedal position switch (view 
with lower instrument panel LH re-
moved)

8.

Stop lamp switch

9.

Brake pedal

10.

Electric throttle control actuator 
(view with intake air duct removed)

11. Throttle valve

12. ASCD steering switch

13. CANCEL switch

14. ON OFF (main) switch

15. SET/COAST switch

16. ACCEL/RES switch

17. Clutch pedal position switch

18. Clutch pedal

Front

EC-32

< SYSTEM DESCRIPTION >

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ENGINE CONTROL SYSTEM

BBIA0640E

MULTIPORT FUEL INJECTION SYSTEM

EC-33

< SYSTEM DESCRIPTION >

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MULTIPORT FUEL INJECTION SYSTEM

System Description

INFOID:0000000009480724

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 signal 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.

<Fuel increase>

• During warm-up

• When starting the engine

• During acceleration

• Hot-engine operation

• When selector lever is changed from N to D (A/T models)

• High-load, high-speed operation

<Fuel decrease>

• During deceleration

• During high engine speed operation

Sensor

Input Signal to ECM

ECM function

Actuator

Crankshaft position sensor (POS)

Engine speed*

3

Fuel injection & mixture 
ratio control

Fuel injector

Camshaft position sensor (PHASE)

Piston position

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 (M/T)
TCM (A/T)

Gear position

Knock sensor

Engine knocking condition

Power steering pressure sensor

Power steering operation

Air fuel ratio (A/F) sensor 1

Density of oxygen in exhaust gas

Heated oxygen sensor 2*

1

Density of oxygen in exhaust gas

Combination meter

Vehicle speed*

2

Air conditioner switch

Air conditioner operation*

2

Battery

Battery voltage*

3

EC-34

< SYSTEM DESCRIPTION >

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MULTIPORT FUEL INJECTION SYSTEM

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 better reduce CO, HC and NOx emissions. This system uses air fuel

ratio (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 air fuel

ratio (A/F) sensor 1, refer to 

EC-197, "Component Description"

. 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 air fuel ratio (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 air fuel ratio (A/F) sensor 1 or its circuit

• Insufficient activation of air fuel ratio (A/F) sensor 1 at low engine coolant temperature

• High engine coolant temperature

• During warm-up

• After shifting from N to D (A/T models)

• When starting the engine

MIXTURE RATIO SELF-LEARNING CONTROL

The mixture ratio feedback control system monitors the mixture ratio signal transmitted from air fuel ratio (A/F)

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., 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 air fuel ratio (A/F) sensor 1 indicates whether the mixture ratio is RICH or LEAN com-

pared 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 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.

PBIB3020E

 

 

 

 

 

 

 

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