Nissan X-Trail 32. Manual - part 730

SYSTEM

EC-49

< SYSTEM DESCRIPTION >

[MR20DD]

C

D

E

F

G

H

I

J

K

L

M

A

EC

N

P

O

JSBIA5021GB

EC-50

< SYSTEM DESCRIPTION >

[MR20DD]

SYSTEM

DIG (DIRECT INJECTION GASOLINE) SYSTEM

JSBIA5022GB

SYSTEM

EC-51

< SYSTEM DESCRIPTION >

[MR20DD]

C

D

E

F

G

H

I

J

K

L

M

A

EC

N

P

O

DIG (DIRECT INJECTION GASOLINE) SYSTEM : System Description

INFOID:0000000010775037

System Diagram

*1: This sensor is not used to control the engine system under normal conditions.

SYSTEM DESCRIPTION

The adoption of the direct fuel injection system [DIG (Direct Injection Gasoline)] enables more accurate adjust-
ment of fuel injection quantity by injecting atomized high-pressure fuel directly into the cylinder. This method
allows high-powered engine, high torque, low fuel consumption, quietness, and emissions-reduction.
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 and fuel rail pressure) from the crankshaft position sensor,
camshaft position sensor, mass air flow sensor and the fuel rail pressure sensor.

FUEL INJECTION CONTROL

Injection Pattern

ECM conducts sequential injection (1 injection per 2 rotations of engine to each cylinder, suitable injection
according to each cylinder's ignition order).

Injection when starting the engine

When starting the engine, ECM determines the amount of fuel injected according to conditions such as engine
coolant temperature to make the starting smoother.
Also, conducts the starting control with stratified-charge combustion according to conditions.

Injection when driving normally

JSBIA5016GB

EC-52

< SYSTEM DESCRIPTION >

[MR20DD]

SYSTEM

Normally, ECM determines the amount of injection to be an optimum air-fuel mixture ratio for homogeneous
combustion.

Cut-in injection when acceleration

When accelerating, according to the opening speed of throttle valve, ECM conducts a cut-in injection adding to
normal injection and improves accelerating performance.

DIRECT FUEL INJECTION CONTROL

Homogeneous Combustion

Homogeneous combustion is a combustion method that fuel is
injected during intake process so that combustion occurs in the
entire combustion chamber, as is common with conventional meth-
ods. As for a start except for starts with the engine cold, homoge-
neous combustion occurs.

Stratified-charge Combustion

Stratified-charge combustion is a combustion method which enables
extremely lean combustion by injecting fuel in the latter half of a
compression process, collecting combustible air-fuel around the
spark plug, and forming fuel-free airspace around the mixture. Right
after a start with the engine cold, the catalyst warm-up is accelerated
by stratified-charge combustion.

VARIOUS FUEL INJECTION INCREASE/DECREASE COMPENSATION

The amount of fuel injected is compensated to improve engine performance under various operating condi-
tions as listed below.

<Fuel increase>

• During warm-up
• When starting the engine
• During acceleration
• Hot-engine operation
• When selector lever position is changed from N to D
• High-load, high-speed operation

<Fuel decrease>

• During deceleration
• During high engine speed operation

MIXTURE RATIO FEEDBACK CONTROL (CLOSED LOOP CONTROL)

JSBIA5017GB

JSBIA5019GB

PBIB2793E