width NISSAN PRIMERA 1999 Electronic User Guide

Mixture Ratio Feedback Control (Closed loop control)NCEC0014S04
The mixture ratio feedback system provides the best air-fuel mixture ratio for driveability and emission con-
trol. The three way catalyst can then better reduce CO, HC and NOx emissions. This system uses a heated
oxygen sensor 1 (front) in the exhaust manifold to monitor if the engine operation is rich or lean. The ECM
adjusts the injection pulse width according to the sensor voltage signal. For more information about the heated
oxygen sensor 1 (front), refer to EC-SR-144. This maintains the mixture ratio within the range of stoichiomet-
ric (ideal air-fuel mixture).
This stage is referred to as the closed loop control condition.
Heated oxygen sensor 2 (rear) is located downstream of the three way catalyst. Even if the switching char-
acteristics of the heated oxygen sensor 1 (front) shift, the air-fuel ratio is controlled to stoichiometric by the
signal from the heated oxygen sensor 2 (rear).
Open Loop ControlNCEC0014S05The 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.
IDeceleration and acceleration
IHigh-load, high-speed operation
IMalfunction of heated oxygen sensor 1 (front) or its circuit
IInsufficient activation of heated oxygen sensor 1 (front) at low engine coolant temperature
IHigh engine coolant temperature
IDuring warm-up
IWhen starting the engine
Mixture Ratio Self-learning ControlNCEC0014S06The mixture ratio feedback control system monitors the mixture ratio signal transmitted from the heated oxy-
gen sensor 1 (front). 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 con-
trolled as originally designed. Both manufacturing differences (i.e., mass air flow sensor hot film) and charac-
teristic changes during operation (i.e., 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 ªinjection pulse durationº to automatically compensate for the difference between
the two ratios.
ªFuel trimº refers to the feedback compensation value compared against the basic injection duration. Fuel trim
includes short term fuel trim and long term fuel trim.
ªShort term fuel trimº is the short-term fuel compensation used to maintain the mixture ratio at its theoretical
value. The signal from the heated oxygen sensor 1 (front) indicates whether the mixture ratio is RICH or LEAN
compared 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.
ªLong term fuel trimº 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.
SEF336WA
ENGINE AND EMISSION BASIC CONTROL
SYSTEM DESCRIPTIONSR20DE
Multiport Fuel Injection (MFI) System (Cont'd)
EC-24

Fuel Injection TimingNCEC0014S07
Two types of systems are used.
Sequential Multiport Fuel Injection System
NCEC0014S0701Fuel 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
NCEC0014S0702Fuel 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-offNCEC0014S08Fuel to each cylinder is cut off during deceleration or operation of the engine at excessively high speeds.
Distributor Ignition (DI) System
DESCRIPTIONNCEC0015Input/Output Signal ChartNCEC0015S01
Sensor Input Signal to ECMECM func-
tionActuator
Camshaft position sensor Engine speed and piston position
Ignition tim-
ing controlPower transistor Mass air flow sensor Amount of intake air
Engine coolant temperature sensor Engine coolant temperature
Throttle position sensorThrottle position
Throttle valve idle position
Vehicle speed sensor or ABS actuator and
electric unit (control unit)Vehicle speed
Ignition switch Start signal
Knock sensor Engine knocking
PNP switch Gear position
Battery Battery voltage
SEF337W
ENGINE AND EMISSION BASIC CONTROL
SYSTEM DESCRIPTIONSR20DE
Multiport Fuel Injection (MFI) System (Cont'd)
EC-25

System DescriptionNCEC0015S02
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
AÉBTDC
During the following conditions, the ignition timing is revised by the ECM according to the other data stored
in the ECM.
IAt starting
IDuring warm-up
IAt idle
IAt low battery voltage
IDuring 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
DESCRIPTIONNCEC0016Input/Output Signal ChartNCEC0016S01
Sensor Input Signal to ECMECM func-
tionActuator
Air conditioner switch Air conditioner ªONº signal
Air condi-
tioner cut
controlAir 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
Refrigerant pressure sensor Refrigerant pressure
Vehicle speed sensor or ABS actuator and
electric unit (control unit)Vehicle speed
Power steering oil pressure switch Power steering operation
System DescriptionNCEC0016S02This system improves engine operation when the air conditioner is used.
Under the following conditions, the air conditioner is turned off.
IWhen the accelerator pedal is fully depressed.
IWhen cranking the engine.
SEF742M
ENGINE AND EMISSION BASIC CONTROL
SYSTEM DESCRIPTIONSR20DE
Distributor Ignition (DI) System (Cont'd)
EC-26

Monitored item [Unit]ECM
input
signalsMain
signalsDescription Remarks
AIR COND SIG
[ON/OFF]qqIIndicates [ON/OFF] condition of the air
conditioner switch as determined by the
air conditioning signal.
P/N POSI SW
[ON/OFF]qqIIndicates [ON/OFF] condition from the
PNP switch signal.
PW/ST SIGNAL
[ON/OFF]qqIIndicates [ON/OFF] condition of the
power steering oil pressure switch deter-
mined by the power steering oil pressure
switch signal.
LOAD SIGNAL
[ON/OFF]qqIIndicates [ON/OFF] condition from the
electrical load signal and/or lighting
switch.
ON ... rear defogger is operating and/or
lighting switch is on.
OFF ... rear defogger is not operating
and lighting switch is not on.
IGNITION SW
[ON/OFF]qIIndicates [ON/OFF] condition from igni-
tion switch.
HEATER FAN SW
[ON/OFF]qIIndicates [ON/OFF] condition from the
heater fan switch.
INJ PULSE -B1
[msec]qIIndicates the actual fuel injection pulse
width compensated by ECM according to
the input signals.IWhen the engine is stopped, a cer-
tain computed value is indicated.
B/FUEL SCHDL
[msec]IªBase fuel scheduleº indicates the fuel
injection pulse width programmed into
ECM, prior to any learned on board cor-
rection.
IGN TIMING [BTDC]qIIndicates the ignition timing computed by
ECM according to the input signals.
IACV-AAC/V [step]qIIndicates the IACV-AAC valve control
value computed by ECM according to
the input signals.
A/F ALPHA -B1 [%]qIIndicates the mean value of the air-fuel
ratio feedback correction factor per
cycle.IWhen the engine is stopped, a cer-
tain value is indicated.
IThis data also includes the data for
the air-fuel ratio learning control.
AIR COND RLY
[ON/OFF]qIIndicates the air conditioner relay control
condition determined by ECM according
to the input signals.
FUEL PUMP RLY
[ON/OFF]qIIndicates the fuel pump relay control
condition determined by ECM according
to the input signals.
COOLING FAN
[HI/LOW/OFF]qIIndicates the control condition of the
cooling fan determined by ECM accord-
ing to the input signals.
HI ... High speed operation
LOW ... Low speed operation
OFF ... Stop
HO2S1 HTR (B1)
[ON/OFF]IIndicates [ON/OFF] condition of heated
oxygen sensor 1 (front) heater deter-
mined by ECM according to the input
signals.
ON BOARD DIAGNOSTIC SYSTEM DESCRIPTIONSR20DE
CONSULT-II (Cont'd)
EC-73

Monitored item [Unit]ECM
input
signalsMain
signalsDescription Remarks
HO2S2 HTR (B1)
[ON/OFF]IIndicates [ON/OFF] condition of heated
oxygen sensor 2 (rear) heater deter-
mined by ECM according to the input
signals.
PURG VOL C/V [%]IIndicates the EVAP canister purge vol-
ume control solenoid valve computed by
the ECM according to the input signals.
IThe opening becomes larger as the
value increases.
CAL/LD VALUE [%]IªCalculated load valueº indicates the
value of the current airflow divided by
peak airflow.
ABSOL TH×P/S [%]IªAbsolute throttle position sensorº indi-
cates the throttle opening computed by
ECM according to the signal voltage of
the throttle position sensor.
MASS AIRFLOW
[gm/s]IIndicates the mass airflow computed by
ECM according to the signal voltage of
the mass air flow sensor.
IDL A/V LEANIDisplay the condition of idle air volume
learning
YET...Idle air volume learning has not
been performed yet.
CMPLT...Idle air volume learning has
already been performed successfully.
INCMP...Idle air volume learning has not
been performed successfully.
TRVL AFTER MIL
[km] or [Mile]IDistance traveled while MI is activated
VOLTAGE [V]IVoltage measured by the voltage probe.
PULSE
[msec] or [Hz] or [%]IPulse width, frequency or duty cycle
measured by the pulse probe.IOnly ª#º is displayed if item is unable
to be measured.
IFigures with ª#ºs are temporary ones.
They are the same figures as an
actual piece of data which was just
previously measured.
DATA MONITOR (SPEC) MODENLEC1365S07
Monitored item [Unit]ECM
input
signalsMain
signalsDescription Remarks
MAS A/F SE-B1 [V]qqIThe signal voltage of the mass air flow sen-
sor specification is displayed.IWhen the engine is running, specifi-
cation range is indicated.
B/FUEL SCHDL
[msec]IªBase fuel scheduleº indicates the fuel injec-
tion pulse width programmed into ECM,
prior to any learned on board correction.IWhen the engine is running, specifi-
cation range is indicated.
A/F ALPHA-B1 [%]qIIndicates the mean value of the air-fuel ratio
feedback correction factor per cycle.IWhen the engine is running, specifi-
cation range is indicated.
IThis data also includes the data for
the air-fuel ratio learning control.
NOTE:
Any monitored item that does not match the vehicle being diagnosed is deleted from the display automatically.
ON BOARD DIAGNOSTIC SYSTEM DESCRIPTIONSR20DE
CONSULT-II (Cont'd)
EC-74

DescriptionNLEC1748The specification (SP) value indicates the tolerance of the value that is displayed in ªDATA MONITOR (SPEC)º
mode of CONSULT-II during normal operation of the Engine Control System. When the value in ªDATA MONI-
TOR (SPEC)º mode is within the SP value, the Engine Control System is confirmed OK. When the value in
ªDATA MONITOR (SPEC)º mode is NOT within the SP value, the Engine Control System may have one or
more malfunctions.
The SP value is used to detect malfunctions that may affect the Engine Control System, but will not light the
MIL.
The SP value will be displayed for the following three items:
IB/FUEL SCHDL (The fuel injection pulse width programmed into ECM prior to any learned on board cor-
rection)
IA/F ALPHA-B1/B2 (The mean value of air-fuel ratio feedback correction factor per cycle)
IMAS A/F SE-B1 (The signal voltage of the mass air flow sensor)
Testing ConditionNLEC1749IVehicle driven distance: More than 5,000 km (3,107 miles)
IBarometric pressure: 98.3 - 104.3 kPa (0.983 - 1.043 bar, 1.003 - 1.064 kg/cm2, 14.25 - 15.12 psi)
IAtmospheric temperature: 20 - 30ÉC (68 - 86ÉF)
IEngine coolant temperature: 75 - 95ÉC (167 - 203ÉF)
ITransmission: Warmed-up*1
IElectrical load: Not applied*2
IEngine speed: Idle
*1: For after the engine is warmed up to normal operating temperature, drive vehicle until ªFLUID TEMP SEº
(CVT fluid temperature sensor signal) indicates less than 0.9V.
*2: Rear window defogger switch, air conditioner switch, lighting switch are ªOFFº. Cooling fans are not oper-
ating. Steering wheel is straight ahead.
SEF601Z
Inspection ProcedureNLEC1750NOTE:
Perform ªDATA MONITOR (SPEC)º mode in maximum scale dis-
play.
1. Perform ªBasic Inspectionº, EC-84.
2. Confirm that the testing conditions indicated above are met.
3. Select ªB/FUEL SCHDLº, ªA/F ALPHA-B1º and ªMAS A/F
SE-B1º in ªDATA MONITOR (SPEC)º mode with CONSULT-II.
4. Make sure that monitor items are within the SP value.
5. If NG, go to ªDiagnostic Procedureº, EC-111.
TROUBLE DIAGNOSIS Ð SPECIFICATION VALUESR20DE
Description
EC-110

3. Heat cylinder head to 110 to 130ÉC (230 to 266ÉF).
4. Press fit valve seat until it seats on the bottom.
5. Cut or grind valve seat using suitable tool to the specified
dimensions as shown in SDS, EM-179.
6. After cutting, lap valve seat with abrasive compound.
7. Check valve seating condition.
Seat face angle ªaº:
45É15¢- 45É45¢
Contacting width ªWº:
Intake
1.06 - 1.34 mm (0.0417 - 0.0528 in)
Exhaust
1.20 - 1.68 mm (0.0472 - 0.0661 in)
8. Use a depth gauge to measure the distance ªLº between the
mounting surface of the cylinder head spring seat and the
valve stem end. If the distance is shorter than specified, repeat
step 5 above to correct it. If the distance is longer, replace the
valve seat.
Valve seat resurface limit:
Intake
35.95 - 36.55 mm (1.4154 - 1.4390 in)
Exhaust
35.92 - 36.52 mm (1.4142 - 1.4378 in)
VALVE DIMENSIONSNCEM0019S12Check dimensions of each valve. Refer to SDS, EM-182 for dimen-
sions.
When valve head has been worn down to 0.5 mm (0.020 in) in
margin thickness, replace valve.
Grinding allowance for valve stem tip is 0.2 mm (0.008 in) or
less.
VALVE SPRINGNCEM0019S13SquarenessNCEM0019S13011. Measure dimension ªSº.
Out-of-square ªSº:
Less than 1.75 mm (0.0689 in)
2. If it exceeds the limit, replace spring.
SEM008AOil
SEM892B
AEM343
SEM188A T (Margin thickness)
SEM288A S (Out-of-square)
CYLINDER HEADQG
Inspection (Cont'd)
EM-39

VALVE SEATS
Check valve seats for any evidence of pitting at valve contact sur-
face. Reset or replace if it has worn out excessively.
IBefore repairing valve seats, check valve and valve guide
for wear. If they have worn, replace them. Then correct
valve seat.
IUse both hands to cut uniformly.
REPLACING VALVE SEAT FOR SERVICE PARTS
1. Bore out old seat until it collapses. Boring should not continue
beyond the bottom face of the seat recess in cylinder head. Set
the machine depth stop to ensure this.
2. Ream cylinder head recess.
Reaming bore for service valve seat
Oversize [0.5 mm (0.020 in)]:
Intake 35.500 - 35.516 mm (1.3976 - 1.3983 in)
Exhaust 31.500 - 31.516 mm (1.2402 - 1.2408 in)
Be sure to ream in circles concentric to the valve guide cen-
ter. This will enable valve seat to fit correctly.
3. Heat cylinder head to 110 to 130ÉC (230 to 266ÉF).
4. Press fit valve seat until it seats on the bottom.
5. Cut or grind valve seat using a suitable tool at the specified
dimensions as shown in SDS (EM-190).
6. After cutting, lap valve seat with abrasive compound.
7. Check valve seating condition.
Seat face angle ªaº:
44É53¢- 45É07¢
Contacting width ªWº:
Intake
1.385 - 1.401 mm (0.0545 - 0.0552 in)
Exhaust
1.385 - 1.401 mm (0.0545 - 0.0552 in)
VALVE DIMENSIONS
Check dimensions in each valve. For dimensions, refer to SDS
(EM-189).
When valve head has been worn down to 0.5 mm (0.020 in) in
margin thickness, replace valve.
Grinding allowance for valve stem tip is 0.2 mm (0.008 in) or
less.
SEM934C
SEM795A
.Recess diameter
SEM008AOil
SEM892B
.SEM188A T (Margin thickness)
CYLINDER HEADSR20DE
Inspection (Cont'd)
EM-95

Using plastigage
1. Wipe off oil from camshaft journal bracket caps and brackets.
2. Install camshaft in journal bracket caps and put plastigage on
each camshaft journal.
3. Install cam bracket caps and tighten cam bracket cap nuts in
the correct order to the specified torque.
: 18 - 22 N´m (1.8 - 2.2 kg-m, 13 - 16 ft-lb)
4. Remove cam bracket caps and measure maximum width of
plastigage.
Camshaft bearing clearance:
Limit
0.1 mm (0.004 in)
5. If clearance appears to exceed the limit, replace camshaft or
cylinder head.
IWhich parts to be replaced should be decided upon after mea-
suring the diameters of the parts concerned.
Valve clearance
Checking
Check valve clearance while engine is warm and not running.
1. Remove rocker cover.
2. Set No. 1 cylinder at TDC on its compression stroke.
IAlign pointer with TDC mark on crankshaft pulley.
ICheck that valve lifters No.
p1andp2are loose and valve
lifters No.
p7andp8are tight.
If not, turn crankshaft one revolution (360É) and align as
described above.
3. Check valve clearances of valve lifter No.
p1,p2,p4and
p6.
SEM879
SEM880
SEM369F
SMA406A
CYLINDER HEADCD20T
Inspection (Cont'd)
EM-148

Valve seat
SR20DE engine
Unit: mm (in)
NEM212
Standard Service
Cylinder head seat recess diameter (D)In. 35.000 - 35.016 (1.3780 - 1.3786) 35.500 - 35.516 (1.3976 - 1.3983)
Ex. 31.000 - 31.016 (1.2205 - 1.2211) 31.500 - 31.516 (1.2402 - 1.2408)
Valve seat interference fitIn. 0.064 - 0.096 (0.0025 - 0.0038)
Ex. 0.064 - 0.096 (0.0025 - 0.0038)
Valve seat outer diameter (d)In. 35.080 - 35.096 (1.3811 - 1.3817) 35.580 - 35.596 (1.4008 - 1.4014)
Ex. 31.080 - 31.096 (1.2236 - 1.2242) 31.580 - 31.596 (1.2433 - 1.2439)
Depth (H)In. 6.25 (0.2461)
Ex. 6.25 (0.2461)
Height (h)6.2 - 6.3 (0.244 - 0.248)
INTAKECylinder head
EXHAUST
Standard Standard
*29.35 - 29.65
(1.1555 - 1.1673)
*44É53¢- 45É07¢
*33.6 - 33.8
(1.323 - 1.331)
Contacting width (W): 1.385 - 1.401
(0.0545 - 0.0552)*44É53¢- 45É07¢
*29.4 -29.6 (1.157 - 1.165)
Contacting width (W): 1.385 - 1.401 (0.0545 - 0.0552)
Oversize
Oversize
*44É53¢- 45É07¢
*33.6 - 33.8
(1.323 - 1.331)
Contacting width (W): 1.385 - 1.401
(0.0545 - 0.0552)
:* Machining data*44É53¢- 45É07¢
*29.4 - 29.6 (1.157 - 1.165)
Contacting width (W): 1.385 - 1.401 (0.0545 - 0.0552)
SERVICE DATA AND SPECIFICATIONS (SDS)SR20DE
Inspection and Adjustment (Cont'd)
EM-190