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Nissan Rogue. Manual - part 443

EC-40

< SYSTEM DESCRIPTION >

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SYSTEM

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

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-24, "Air Fuel Ratio (A/F) Sensor 1"

. 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.

PBIB2793E

SYSTEM

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“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.

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 four cylinders twice each engine cycle. In other words, pulse signals

of the same width are simultaneously transmitted from the ECM.

The four 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, operation of the engine at excessively high speeds or oper-

ation of the vehicle at excessively high speeds.

ELECTRIC IGNITION SYSTEM
ELECTRIC IGNITION SYSTEM : System Description

INFOID:0000000011277856

SYSTEM DIAGRAM

SYSTEM DESCRIPTION

Firing order: 1 - 3 - 4 - 2

The ignition timing is controlled by the ECM to maintain the best air-fuel ratio for every running condition of the

engine. The ignition timing data is stored in the ECM.

SEF337W

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SYSTEM

The ECM receives information such as the injection pulse width and camshaft position sensor (PHASE) sig-

nal. Computing this information, ignition signals are transmitted to the power transistor.

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

• 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.

INTAKE VALVE TIMING CONTROL
INTAKE VALVE TIMING CONTROL : System Description

INFOID:0000000011277857

INTAKE VALVE TIMING CONTROL

System Diagram

System Description

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SYSTEM

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This mechanism hydraulically controls cam phases continuously with the fixed operating angle of the intake

valve.

The ECM receives signals such as crankshaft position, camshaft position, engine speed, and engine coolant

temperature. Then, the ECM sends ON/OFF pulse duty signals to the intake valve timing (IVT) control sole-

noid valve depending on driving status. This makes it possible to control the shut/open timing of the intake

valve to increase engine torque in low/mid speed range and output in high-speed range.

INTAKE VALVE TIMING INTERMEDIATE LOCK CONTROL

System Diagram

System Description

The intake valve timing intermediate lock control improves the cleaning ability of exhaust gas at cold starting

by fixing the camshaft sprocket (INT) with two lock keys and bringing the cam phase into intermediate phase.

Cam phase is fixed at the intermediate phase by two lock keys in the camshaft sprocket (INT). Lock key 1 con-

trols retard position and lock key 2 controls advance position.

ECM controls the intermediate phase lock by opening/closing the intake valve timing intermediate lock control

solenoid valve to control oil pressure acting on the lock key and locking/unlocking the lock key.

Lock/Unlock Activation

When ECM activates the intake valve timing intermediate lock control solenoid valve, oil pressure generated in

the oil pump is drained through the oil pressure path in the control valve. Since oil pressure is not acted on the

lock key, the lock key position is fixed by the spring tension and the cam phase is fixed at the intermediate

phase.

When ECM deactivates the intake valve timing intermediate lock control solenoid valve, unlocking oil pressure

acts on each lock key. Lock key 1 is not released because it is under load due to sprocket rotational force. For

JPBIA5973GB

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