engine NISSAN ALMERA N15 1995 Service Manual

ENGINEANDEMISSION BASICCONTROL SYSTEMDESCRIPTION
Multiport FuelInjection (MFI)System
INPUT/OUTPUT SIGNALLINE

Camshaft positionsensor
Mass airflow sensor
Engine coolant temperature sensor
Front heated oxygen sensor
Throttle position sensor
Neutral position/lnhibitor switch

I
Vehicle speedsensor
Ignition switch
Air conditioner switch
Battery Engine
speedandpiston position
Amount ofintake air
Engine coolant temperature
Density ofoxygen inexhaust gas
Throttle position
Throttle valveidleposition
Gear position

I
Vehicle speed
Start signal
Air conditioner operation
Battery voltage ECM
(ECCS
control
module) Injector
•

BASIC MULTIPORT FUELINJECTION
SYSTEM

The amount offuel injected fromthefuel injector
is determined bythe ECM. TheECM controls the
length oftime thevalve remains open(injection
pulse duration). Theamount offuel injected isa
program valueinthe ECM memory. Theprogram
value ispreset byengine operating conditions.
These conditions aredetermined byinput signals
(for engine speedandintake air)from boththe
camshaft positionsensorandthemass airflow
sensor.
VARIOUS
FUELINJECTION
INCREASE/DECREASE COMPENSATION

In addition, theamount offuel injected iscom-
pensated toimprove engineperformance under
various operating conditions aslisted below.

<
Fuel increase>
• During warm-up
• When starting theengine
• During acceleration
• Hot-engine operation
• When selector leverischanged from"N"to
"0" (AfT models only)
• High-load operation

<
Fuel decrease>
• During deceleration

EC-233

ENGINEANDEMISSION BASICCONTROL SYSTEMDESCRIPTION [][]
Multiport FuelInjection (MFI)System (Cont'd)
CLOSED LOOP MIXTURERATIOFEEDBACK CONTROL(CLOSEDLOOP
CONTROL CONTROL)

The mixture ratiofeedback systemprovides thebest air-fuel

Feedback signal
mixtureratiofordriveability andemission control.Thethree
way catalyst canthen better reduce CO,HCand NOx emissions.
This system usesaheated oxygen sensorinthe exhaust man-
ifold tomonitor ifthe engine operation isrich orlean. TheECM
adjusts theinjection pulsewidthaccording tothe sensor volt-
age signal. Formore information abouttheheated oxygen
sensor, refertoEC-362. Thismaintains themixture ratiowithin

MEF025DD
therange ofstoichiometric (idealair-fuel mixture).
This stage isreferred toas the closed loopcontrol condition.

OPEN LOOPCONTROL

The open loopsystem condition referstowhen theECM detects
any ofthe following conditions. Feedbackcontrolstopsinorder
to maintain stabilized fuelcombustion.
• Deceleration andacceleration
• High-load, high-speed operation
• Engine idling
• Malfunction ofheated oxygen sensororits circuit
• Insufficient activationofheated oxygen sensoratlow
engine coolant temperature
• High-engine coolanttemperature
• After shifting from"N"to"0"
• During warm-up
• When starting theengine

MIXTURE RATIOSELF-LEARNING CONTROL

The mixture ratiofeedback controlsystem monitors themixture
ratio signal transmitted fromtheheated oxygen sensor. This
feedback signalisthen senttothe ECM. TheECM controls the
basic mixture ratioasclose tothe theoretical mixtureratioas
possible. However, thebasic mixture ratioisnot necessarily con-
trolled asoriginally designed. Bothmanufacturing differences
(Le., mass airflow sensor hotwire) andcharacteristic changes
during operation (Le.,injector clogging) directlyaffectmixture
ratio.
Accordingly, thedifference betweenthebasic andtheoretical
mixture ratiosismonitored inthis system. Thisisthen com-
puted interms of"injection pulseduration" toautomatically
compensate forthe difference betweenthetwo ratios.

EC-234

Twotypes ofsystems areused.

Sequential multiportfuelinjection system

Fuel isinjected intoeach cylinder duringeachengine cycle
according tothe firing order. Thissystem isused when the
engine isrunning.

ENGINE
ANDEMISSION BASICCONTROL SYSTEMDESCRIPTION ~
Multiport FuelInjection (MFI)System (Cont'd)
FUEL INJECTION TIMING

..--./ Injection pulse
NO.1 cylinder
---1
0/1 _
NO.3 cylinder
~n~ _

No.2
cylinder
rL

NO.4 cylinder
~n~_

~ 1engine cycle
----j

Sequential multiportfuelinjection system

MEF522D

No. 1cylinder
jl
n

rL-

No. 2cylinder
jl
n

rL-

No. 3cylinder
]l
n

rL-

NO.4 cylinder
D
n
fL-.

~- 1engine cycle
---1

Simultaneous multiportfuelinjection system

MEF523D Simultaneous
multipartfuelinjection system

Fuel isinjected simultaneously intoallfour cylinders twiceeach
engine cycle.Inother words, pulsesignals ofthe same width
are simultaneously transmittedfromtheECM.
The four injectors willthen receive thesignals twotimes for
each engine cycle.
This system isused when theengine isbeing started and/orif
the fail-safe system(CPU)isoperating.

FUEL SHUT-OFF

Fuel toeach cylinder iscut offduring deceleration oroperation
of the engine atexcessively highspeeds.
•

Distributor Ignition(DI)System
INPUT/OUTPUT SIGNALLINE

Camshaft positionsensor Engine
speedandpiston position
Mass airflow sensor Amount
ofintake air
Engine coolant temperature sensor Engine
coolant temperature
Throttle position sensor

I
Vehicle speedsensor Throttle
position
Throttle valveidleposition

I
Vehicle speed ECM
(ECCS
control module) Power
transistor
Ignition switch Start
signal
Knock sensor Engine
knocking
Neutral position/Inhibitor switchGear
position
Battery Battery
voltage

EC-235

A
N

600 1,000 1,4001,8002,200

Engine speed(rpm) SEF742M

Tp

(msec)

1.75
~ 1.50

.~

3l
1.25

:;
a.

c:
1.00

.Q
~ 0.75
E ENGINE
ANDEMISSION BASICCONTROL SYSTEMDESCRIPTION
Distributor Ignition(01)System (Cont'd)
SYSTEM DESCRIPTION

The ignition timingiscontrolled bythe ECM tomaintain thebest
air-fuel ratioforevery running condition ofthe engine.
The ignition timingdataisstored inthe ECM. Thisdataforms
the map shown.
The ECM receives information suchasthe injection pulsewidth
and camshaft positionsensorsignal.Computing this
information, ignitionsignalsaretransmitted tothe power tran-
sistor.
e.g., N:1,800 rpm,Tp:1.50 msec
AOBTDC
During thefollowing conditions, theignition timingisrevised by
the ECM according tothe other datastored inthe ECM.
• Atstarting
• During warm-up
• Atidle
• Hot engine operation
• During acceleration
The knock sensor retardsystem isdesigned onlyforemergen-
cies. Thebasic ignition timingisprogrammed withintheanti-
knocking zone,ifrecommended fuelisused under drycondi-
tions. Theretard system doesnotoperate undernormal driv-
ing conditions.
If engine knocking occurs,theknock sensor monitors thecon-
dition. Thesignal istransmitted tothe ECM (ECCS control mod-
ule). TheECM retards theignition timingtoeliminate thek.nock-
ing condition.

Air Conditioning CutControl
INPUT/OUTPUT SIGNALLINE

Air conditioner switch
Throttle position sensor
Camshaft positionsensor
Engine coolant temperature sensor
Ignition switch Air
conditioner "ON"signal
Throttle valveopening angle
Engine speed
Engine coolant temperature
Start signal
ECM

(ECCS
control module)
Air

condi-
tioner
relay

SYSTEM DESCRIPTION

This system improves acceleration whentheairconditioner isused.
When theaccelerator pedalisfully depressed, theairconditioner isturned offfor afew seconds.
When engine coolant temperature becomesexcessively high,theairconditioner isturned off.This con-
tinues untilthecoolant temperature returnstonormal.

EC-236

ENGINEANDEMISSION BASICCONTROL SYSTEMDESCRIPTION
Fuel CutControl (atnoload
&
high engine
speed)
INPUT/OUTPUT SIGNALLINE

Vehicle speedsensor Vehicle
speed
Neutral position/lnhibitor switch
Throllle positionsensor
Engine coolant temperature sensor
Camshaft positionsensor Neutral
position
Throllle position
Engine coolant temperature

.

Engine speed
ECM

(ECCS
control module) Injectors

•

If the engine speedisabove 3,950rpmwith noload (for
example, inneutral andengine speedover3,950 rpm)fuelwill
be cut offafter some time.Theexact timewhen thefuel iscut
off varies basedonengine speed.
Fuel cutwill operate untiltheengine speedreaches 1,150rpm,
then fuelcutiscancelled.

NOTE:

This function isdifferent thandeceleration controllistedunder
"Multipart FuelInjection (MFI)System" onEC-233.
EC-237

EVAPORATIVEEMISSIONSYSTEM
Description
yAir.. Fuelvapor
EGR
valve
&
EVAP canister purgecontrol
solenoid valve

-

EVAP canister
Vapor
ventline

-

Fuel fillercap
with vacuum
relief valve

t

Fuel tank
MEF609DC

The evaporative emissionsystemisused toreduce hydrocar-
bons emitted intotheatmosphere fromthefuel system. This
reduction ofhydrocarbons isaccomplished byactivated char-
coals inthe EVAP canister.
The fuelvapor fromsealed fueltank isled into theEVAP can-
ister when theengine isoff. The fuelvapor isthen stored inthe
EVAP canister. TheEVAP canister retainsthefuel vapor until
the EVAP canister ispurged byair.
When theengine isrunning, theairisdrawn through thebot-
tom ofthe EVAP canister. Thefuelvapor willthen beled tothe
intake manifold.
When theengine runsatidle, thepurge control valveisclosed.
Only asmall amount ofvapor flowsintotheintake manifold
through theconstant purgeorifice.
As the engine speedincreases andthethrottle vacuum rises,
the purge control valveopens. Thevapor issucked through
both main purge and.constant purgeorifices.

Inspection
EVAP CANISTER

Check EVAPcanister asfollows:
1. Blow airinport
@
and ensure thatthere isno leakage.

2.

• Apply vacuum toport
@.
[Approximately
-13.3
to
-20.0
kPa

(-133
to
-200
mbar,
-100
to
-150
mmHg,
-3.94
to
-5.91
inHg)]
• Cover port
CID
with hand.
• Blow airinport
@
and ensure freeflow outofport
@.

SEF312N
EC-238

POSITIVECRANKCASE VENTILATION
Description

This system returnsblow-by gastothe intake
manifold collector.
The positive crankcase ventilation (PCV)valveis
provided toconduct crankcase blow-bygastothe
intake manifold.
During partialthrottle operation ofthe engine, the
intake manifold suckstheblow-by gasthrough
the
pev
valve.
Normally, thecapacity ofthe valve issufficient to
handle anyblow-by andasmall amount ofventi-
lating air.
The ventilating airisthen drawn fromtheairduct into
thecrankcase. Inthis process theairpasses
through thehose connecting airinlet tubes to
rocker cover.
Under full-throttle condition,themanifold vacuum
is insufficient todraw theblow-by flowthrough
the valve. Theflow goes through thehose con-
nection inthe reverse direction.
On vehicles withanexcessively highblow-by, the
valve doesnotmeet therequirement. Thisis
because someofthe flow willgothrough the
hose connection tothe intake manifold collector
under allconditions.

Oil separator

q
Freshair
.. Blow-by gas

ct>
Blow-by gasduring
high-load operation Baffle
plate
PCV
valve operation

Engine notrunning
or backfiring Cruising

~~
.0

Idling or Acceleration
or
decelerating high
load

-~--
.~
AEC923
Inspection
PCV (Positive Crankcase Ventilation)

With engine running atidle, remove PCVvalve fromrocker
cover. Aproperly workingvalvemakes ahissing noiseasair
passes through it.Astrong vacuum shouldbefelt immediately
when afinger isplaced overthevalve inlet.

AEC911 VENTILATION HOSE

1. Check hosesandhose connections forleaks.
2. Disconnect allhoses andclean withcompressed air.Ifany
hose cannot befreed ofobstructions, replace.

ET277 EC-240

~U5e
box
~~~

~11~1-
Datalinkconnector ~"

for CONSULT
t=====/
• FUEL PRESRELEASE. D
FUEL PUMP WillSTOP BY
TOUCHING STARTDURING
IDLE.
CRANK AFEW TIMES AFTER
ENGINE STALL

---S-T~-RT--
BASIC
SERVICE PROCEDURE
Fuel Pressure Release
Before disconnecting fuelline, release fuelpressure fromfuel
line toeliminate danger.

~ 1.Turn ignition switch"ON".

\J!I}
2.Perform "FUELPRESSURE RELEASE"in"WORK
SUPPORT" modewithCONSULT.
3. Start engine.
4. After engine stalls,crankittwo orthree times to
release allfuel pressure.
5. Turn ignition switch"OFF".

•

@ ~:

3.
SEF823K
SEF921P
SEF034K
Remove
fuseforfuel pump.
Start engine.
After engine stalls,crank
it
two orthree times to
release allfuel pressure.
4. Turn ignition switchoffand reconnect fuelpump
fuse.

Fuel Pressure Check
• When reconnecting fuelline, always usenew clamps.
• Make surethatclamp screwdoesnotcontact adjacent
parts.
• Use atorque drivertotighten clamps.
• Use Pressure Gaugetocheck fuelpressure.
• Donot perform fuelpressure checkwithsystem operating.
Fuel pressure gaugemayindicate falsereadings.

1. Release fuelpressure tozero.
2. Disconnect fuelhose between fuelfilter andfuel tube
(engine side).
3. Install pressure gaugebetween fuelfilter andfuel tube.
4. Start engine andcheck forfuel leakage.
5. Read theindication offuel pressure gauge.

At idling:
With vacuum hoseconnected
Approximately 235kPa (2.35 bar,2.4kg/cm
2,
34psi)
With vacuum hosedisconnected
Approximately 294kPa (2.94 bar,3.0kg/cm
2,
43psi)
If
results areunsatisfactory, performFuelPressure Regula-
tor Check.

EC-241

BASICSERVICE PROCEDURE
SEF310R

Vacuum
Fuelpressure

.... L
To
pressure regulator

SEF718B

'nsu'a,or~7

a-ring~1 ~
~> ~

InsUlalor~7
OJ'

Om~riJ$ _.
~lnjeCIOr

kJ

Insulator
11+-
1

~'I"
Localeplate
•. onthis side.
a-ring .
I

FuellUbe~i '.
assembly ,.
~'nsulator
I
SEF616N
MEC710B Fuel
Pressure Regulator Check

1. Stop engine anddisconnect fuelpressure regulator vacuum
hose from intake manifold.
2. Plug intake manifold witharubber cap.
3. Connect variable vacuumsourcetofuel pressure regulator.
4. Start engine andread indication offuel pressure gaugeas
vacuum ischanged.

Fuel pressure shoulddecrease asvacuum increases. Ifresults
are unsatisfactory, replacefuelpressure regulator.
Injector Removal andInstallation

1. Release fuelpressure tozero.
2. Disconnect vacuumhosefrompressure regulator.
3. Disconnect fuelhoses fromfueltube assembly.
4. Disconnect injectorharness connectors.
5. Remove injectors withfueltube assembly.
• Push injector tailpiece.
• Donot pull onthe connector.
6. Install injectors.
• Clean exterior ofinjector tailpiece.
• Use new O-rings.
7. Install injectors withfueltube assembly tointake manifold.
8. Install fuelhoses tofuel tube assembly.
9. Reinstall anyparts removed inreverse orderofremoval.

CAUTION:
After properly connecting fuelhose toinjector andfuel tube
assembly, checkconnection forfuel leakage.
EC-242

BASICSERVICE PROCEDURE
Idle Speedllgnition TiminglldleMixtureRatio
Adjustment
PREPARATION

• Make surethatthefollowing partsarein
good order.
(1) Battery
(2) Ignition system
(3) Engine oiland coolant levels
(4) Fuses
(5) ECM harness connector
(6) Vacuum hoses
(7) Airintake system
(Oil filler cap,oillevel gauge, etc.)
(8) Fuel pressure
(9) Engine compression
(10) Throttle valve

Overall inspection sequence

INSPECTION
•
•
•
•
•
•
On
models equipped withairconditioner,
checks shouldbecarried outwhile theair
conditioner is"OFF".
On models equipped withautomatic
transaxle, whenchecking idlespeed, ignition
timing andmixture ratio,checks shouldbe
carried outwhile shiftlever isin "N" position.
When measuring "CO"percentage, insert
probe morethan40cm (15.7 in)into tailpipe.
Turn offheadlamps, heaterblower, rear
defogger. Keep frontwheels pointed straight ahead.
Make thecheck afterthecooling fanhas
stopped.
•

Perform diagnostic testmode II
(Self-diagnostic results).

OK

Check
&
adjust ignition timing.
Check
&
adjust idlespeed.
Check heated oxygen sensor
function. NG
Repair orreplace.
NG Check heated oxygen sensor
harness. NG
Repair orreplace harness.
OK OK
Check CO%. OKReplace heatedoxygen sensor.

NG

INSPECTION END Check
emission controlparts
and repair orreplace ifneces-
sary.

EC-243
NG
Check heated oxygen sensor
function.
OK