Infiniti G20 (P11). Manual - part 155

Fuel Injection Timing

NCEC0014S07

SEF337W

Two types of systems are used.
Sequential Multiport Fuel Injection System

NCEC0014S0701

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

NCEC0014S0702

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

NCEC0014S08

Fuel to each cylinder is cut off during deceleration or operation of the engine at excessively high speeds.

Distributor Ignition (DI) System

DESCRIPTION

NCEC0015

Input/Output Signal Chart

NCEC0015S01

Sensor

Input Signal to ECM

ECM func-

tion

Actuator

Camshaft position sensor

Engine speed and piston position

Ignition tim-
ing control

Power transistor

Mass air flow sensor

Amount of intake air

Engine coolant temperature sensor

Engine coolant temperature

Throttle position sensor

Throttle position
Throttle valve idle position

Vehicle speed sensor

Vehicle speed

Ignition switch

Start signal

Knock sensor

Engine knocking

PNP switch

Gear position

Battery

Battery voltage

IDX

ENGINE AND EMISSION BASIC CONTROL SYSTEM DESCRIPTION

Multiport Fuel Injection (MFI) System (Cont’d)

EC-31

System Description

NCEC0015S02

SEF742M

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. This data forms the map shown above.
The ECM receives information such as the injection pulse width and camshaft position sensor signal. Com-
puting this information, ignition signals are transmitted to the power transistor.
e.g.,

N: 1,800 rpm, Tp: 1.50 msec

A°BTDC

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.

Air Conditioning Cut Control

DESCRIPTION

NCEC0016

Input/Output Signal Chart

NCEC0016S01

Sensor

Input Signal to ECM

ECM func-

tion

Actuator

Air conditioner switch

Air conditioner “ON” signal

Air condi-
tioner cut
control

Air conditioner relay

PNP switch

Neutral position

Throttle position sensor

Throttle valve opening angle

Camshaft position sensor

Engine speed

Engine coolant temperature sensor

Engine coolant temperature

Ignition switch

Start signal

System Description

NCEC0016S02

This system improves engine operation when the air conditioner is used.
Under the following conditions, the air conditioner is turned off.

When the accelerator pedal is fully depressed.

When cranking the engine.

At high engine speeds.

When the engine coolant temperature becomes excessively high.

When operating power steering during low engine speed or low vehicle speed.

When engine speed is excessively low.

ENGINE AND EMISSION BASIC CONTROL SYSTEM DESCRIPTION

Distributor Ignition (DI) System (Cont’d)

EC-32

Fuel Cut Control (at no load & high engine
speed)

DESCRIPTION

NCEC0017

Input/Output Signal Chart

NCEC0017S01

Sensor

Input Signal to ECM

ECM func-

tion

Actuator

Vehicle speed sensor

Vehicle speed

Fuel cut
control

Injectors

PNP switch

Neutral position

Throttle position sensor

Throttle position

Engine coolant temperature sensor

Engine coolant temperature

Camshaft position sensor

Engine speed

If the engine speed is above 3,950 rpm with no load, (for example, in Neutral and engine speed over 4,000
rpm) fuel will be cut off after some time. The exact time when the fuel is cut off varies based on engine speed.
Fuel cut will operate until the engine speed reaches 1,150 rpm, then fuel cut is cancelled.
NOTE:
This function is different from deceleration control listed under “Multiport Fuel Injection (MFI) System”,
EC-29.

Evaporative Emission System

DESCRIPTION

NCEC0018

SEF569XA

The evaporative emission system is used to reduce hydrocarbons emitted into the atmosphere from the fuel
system. This reduction of hydrocarbons is accomplished by activated charcoals in the EVAP canister.
The fuel vapor in the sealed fuel tank is led into the EVAP canister which contains activated carbon and the
vapor is stored there when the engine is not operating or when refueling to the fuel tank.
The vapor in the EVAP canister is purged by the air through the purge line to the intake manifold when the
engine is operating.
EVAP canister purge volume control solenoid valve is controlled by ECM. When the engine operates, the flow
rate of vapor controlled by EVAP canister purge volume control solenoid valve is proportionally regulated as
the air flow increases.
EVAP canister purge control solenoid valve also shuts off the vapor purge line during decelerating and idling.

IDX

ENGINE AND EMISSION BASIC CONTROL SYSTEM DESCRIPTION

Fuel Cut Control (at no load & high engine speed)

EC-33

SEF396T

INSPECTION

NCEC0019

EVAP Canister

NCEC0019S01

Check EVAP canister as follows:
1.

Pinch the fresh air hose.

Blow air into port A and check that air flows freely through port
B.

AEC778A

Tightening Torque

NCEC0019S02

Tighten EVAP canister as shown in the figure.
Make sure new O-ring is installed properly between EVAP can-
ister and EVAP canister vent control valve.

SEF427N

SEF943S

Fuel Tank Vacuum Relief Valve (Built into fuel filler cap)

NCEC0019S03

Wipe clean valve housing.

Check valve opening pressure and vacuum.

Pressure:

15.3 - 20.0 kPa (0.156 - 0.204 kg/cm

, 2.22 - 2.90 psi)

Vacuum:

−6.0 to −3.4 kPa (−0.061 to −0.035 kg/cm

, −0.87 to

−0.49 psi)

If out of specification, replace fuel filler cap as an assembly.

CAUTION:

Use only a genuine NISSAN fuel filler cap as a replacement. If
an incorrect fuel filler cap is used, the MIL may come on.

Vacuum Cut Valve and Vacuum Cut Valve Bypass Valve

NCEC0019S05

Refer to EC-568.

Evaporative Emission (EVAP) Canister Purge Volume
Control Solenoid Valve

NCEC0019S06

Refer to EC-382.

Fuel Tank Temperature Sensor

NCEC0019S08

Refer to EC-286.

ENGINE AND EMISSION BASIC CONTROL SYSTEM DESCRIPTION

Evaporative Emission System (Cont’d)

EC-34

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