2003 NISSAN X-TRAIL Fuel system

EC-36
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ENGINE CONTROL SYSTEM


When starting the engine
MIXTURE RATIO SELF-LEARNING CONTROL
The mixture ratio feedback control system monitors the mixture ratio signal transmitted from heated oxygen
sensor 1. 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 controlled as orig-
inally designed. Both manufacturing differences (i.e., mass air flow sensor hot wire) and characteristic
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 “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.
“Short term fuel trim” is the short-term fuel compensation used to maintain the mixture ratio at its theoretical
value. The signal from heated oxygen sensor 1 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.
“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 or operation of the engine at excessively high speeds.
SEF337W

ENGINE CONTROL SYSTEM
EC-37
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Electronic Ignition (EI) SystemEBS010LA
INPUT/OUTPUT SIGNAL CHART
*1: This signal is sent to the ECM through CAN communication line.
*2: ECM determines the start signal status by the signals of engine speed and battery voltage.
SYSTEM DESCRIPTION
The ignition timing is controlled by the ECM to maintain the best air-
fuel ratio for every running condition of the engine. The ignition tim-
ing data is stored in the ECM. This data forms the map shown.
The ECM receives information such as the injection pulse width and
camshaft position sensor signal. Computing 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 ControlEBS010LB
INPUT/OUTPUT SIGNAL CHART
*1: This signal is sent to the ECM through CAN communication line.
*2: ECM determines the start signal status by the signals of engine speed and battery voltage.Sensor Input Signal to ECMECM func-
tionActuator
Crankshaft position sensor (POS)
Engine speed*
2
piston position
Ignition
timing con-
trolPower transistor Camshaft position sensor (PHASE)
Mass air flow sensor Amount of intake air
Engine coolant temperature sensor Engine coolant temperature
Throttle position sensor Throttle position
Accelerator pedal position sensor Accelerator pedal position
Knock sensor Engine knocking
Park/neutral position (PNP) switch Gear position
Battery
Battery voltage*
2
Wheel sensor*1Vehicle speed
SEF742M
Sensor Input Signal to ECM ECM function Actuator
Air conditioner switch Air conditioner ON signal
Air conditioner
cut controlAir conditioner relay Throttle position sensor Throttle valve opening angle
Crankshaft position sensor (POS)
Camshaft position sensor (PHASE)Engine speed*
2
Engine coolant temperature sensor Engine coolant temperature
Battery
Battery voltage*
2
Refrigerant pressure sensor Refrigerant pressure
Power steering pressure sensor Power steering operation
Wheel sensor*
1Vehicle speed

EC-38
[QR (WITH EURO-OBD)]
ENGINE CONTROL SYSTEM

SYSTEM DESCRIPTION
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.

When refrigerant pressure is excessively low or high.
Fuel Cut Control (at No Load and High Engine Speed)EBS010LC
INPUT/OUTPUT SIGNAL CHART
*: This signal is sent to the ECM through CAN communication line.
SYSTEM DESCRIPTION
If the engine speed is above 1,800 rpm under no load (for example, the shift position is neutral and engine
speed is over 1,800 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 be operated until the engine speed reaches 1,500 rpm, then fuel cut will be cancelled.
NOTE:
This function is different from deceleration control listed under Multiport Fuel Injection (MFI) System, EC-34
.
CAN Communication UnitEBS010LD
SYSTEM DESCRIPTION
CAN (Controller Area Network) is a serial communication line for real time application. It is an on-vehicle mul-
tiplex communication line with high data communication speed and excellent error detection ability. Many elec-
tronic control units are equipped onto a vehicle, and each control unit shares information and links with other
control units during operation (not independent). In CAN communication, control units are connected with 2
communication lines (CAN H line, CAN L line) allowing a high rate of information transmission with less wiring.
Each control unit transmits/receives data but selectively reads required data only.
Sensor Input Signal to ECM ECM function Actuator
Park/neutral position (PNP) switch Neutral position
Fuel cut control Fuel injector Accelerator pedal position sensor Accelerator pedal position
Engine coolant temperature sensor Engine coolant temperature
Crankshaft position sensor (POS)
Camshaft position sensor (PHASE)Engine speed
Wheel sensor* Vehicle speed

EC-48
[QR (WITH EURO-OBD)]
BASIC SERVICE PROCEDURE

12. Rev up the engine two or three times and make sure that idle speed and ignition timing are within the
specifications.
13. If idle speed and ignition timing are not within the specification, Idle Air Volume Learning will not be carried
out successfully. In this case, find the cause of the incident by referring to the DIAGNOSTIC PROCE-
DURE below.
DIAGNOSTIC PROCEDURE
If idle air volume learning cannot be performed successfully, proceed as follows:
1.Check that throttle valve is fully closed.
2.Check PCV valve operation.
3.Check that downstream of throttle valve is free from air leakage.
4.When the above three items check out OK, engine component parts and their installation condi-
tion are questionable. Check and eliminate the cause of the incident.
It is useful to perform EC-119, "
TROUBLE DIAGNOSIS - SPECIFICATION VALUE" .
5.If any of the following conditions occur after the engine has started, eliminate the cause of the
incident and perform Idle Air Volume Learning all over again:

Engine stalls.

Erroneous idle.
Fuel Pressure CheckEBS010LI
FUEL PRESSURE RELEASE
With CONSULT-II
1. Turn ignition switch ON.
2. Perform “FUEL PRESSURE RELEASE” in “WORK SUPPORT”
mode with CONSULT-II.
3. Start engine.
4. After engine stalls, crank it 2 or 3 times to release all fuel pres-
sure.
5. Turn ignition switch OFF.
Without CONSULT-II
1. Remove fuel pump fuse located in fuse box.
2. Start engine.
3. After engine stalls, crank it 2 or 3 times to release all fuel pres-
sure.
4. Turn ignition switch OFF.
5. Reinstall fuel pump fuse after servicing fuel system.
FUEL PRESSURE CHECK
Before disconnecting fuel line, release fuel pressure from fuel line to eliminate danger.
ITEM SPECIFICATION
Idle speed QR20DE with M/T models: 650±50 rpm (in Neutral position)
Except above: 700±50 rpm [in P or N (A/T), Neutral (M/T) position]
Ignition timing M/T: 15±5° BTDC (in Neutral position)
A/T: 15±5° BTDC (in P or N position)
SEF214Y
PBIB0508E

BASIC SERVICE PROCEDURE
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NOTE:
Prepare pans or saucers under the disconnected fuel line because the fuel may spill out. The fuel pres-
sure cannot be completely released because T30 models do not have fuel return system.
CAUTION:

The fuel hose connection method used when taking fuel pressure check must not be used for
other purposes.

Be careful not to scratch or put debris around connection area when servicing, so that the quick
connector maintains sealability with O-rings inside.

When installing fuel hose quick connector, refer to EM-17, "INTAKE MANIFOLD" .
1. Release fuel pressure to zero. Refer to EC-48, "
FUEL PRESSURE RELEASE" .
2. Prepare fuel hose and fuel hose clamp for fuel pressure check, and connect fuel pressure gauge.

Use suitable fuel hose for fuel pressure check (genuine NISSAN fuel hose without quick connector).

To avoid unnecessary force or tension to hose, use moderately long fuel hose for fuel pressure check.

Do not use the fuel hose for checking fuel pressure with damage or cracks on it.

Use Pressure Gauge to check fuel pressure.
3. Remove fuel hose. Refer to EM-17, "
INTAKE MANIFOLD" .

Do not twist or kink fuel hose because it is plastic hose.

Do not remove fuel hose from quick connector.

Keep the original fuel hose to be free from intrusion of dust or foreign substances with a suitable cover.
4. Install the fuel pressure gauge as shown in the figure.

Wipe off oil or dirt from hose insertion part using cloth moist-
ened with gasoline.

Apply proper amount of gasoline between top of the fuel tube
and No.1 spool.

Insert fuel hose for fuel pressure check until it touches the
No.1 spool on fuel tube.

Use NISSAN genuine hose clamp (part number: 16439
N4710 or 16439 40U00).

When reconnecting fuel line, always use new clamps.

When reconnecting fuel hose, check the original fuel hose for
damage and abnormality.

Use a torque driver to tighten clamps.

Install hose clamp to the position within 1 - 2 mm (0.04 - 0.08
in).

Make sure that clamp screw does not contact adjacent parts.
5. After connecting fuel hose for fuel pressure check, pull the hose
with a force of approximately 98 N (10 kg, 22 lb) to confirm fuel
tube does not come off.
6. Turn ignition switch ON, and check for fuel leakage.
7. Start engine and check for fuel leakage.
8. Read the indication of fuel pressure gauge.

Do not perform fuel pressure check with system operating. Fuel pressure gauge may indicate false
readings.

During fuel pressure check, confirm for fuel leakage from fuel connection every 3 minutes.
9. If result is unsatisfactory, go to next step.
10. Check the following.

Fuel hoses and fuel tubes for cloggingTightening
torque:1 - 1.5 N·m (0.1 - 0.15 kg-m, 9 - 13 in-lb)
At idling: Approximately 350 kPa (3.5 bar, 3.57 kg/cm
2 , 51 psi)
PBIB0669E
PBIB1977E

EC-52
[QR (WITH EURO-OBD)]
ON BOARD DIAGNOSTIC (OBD) SYSTEM

The fail-safe function also operates when above diagnoses except MI circuit are detected and demands the
driver to repair the trouble.
Emission-related Diagnostic InformationEBS010LL
EMISSION-RELATED DIAGNOSTIC INFORMATION ITEMS
Engine operating condition in fail-safe mode Engine speed will not rise more than 2,500 rpm due to the fuel cut
Items
(CONSULT-II screen terms)DTC*
1
SRT codeTe s t Va l v e /
Test Limit
(GST only)1st trip DTC Reference page
CONSULT-II
GST*
2ECM*3
CAN COMM CIRCUIT U1000
1000*5———EC-132
CAN COMM CIRCUIT U1001
1001*5——×EC-132
NO DTC IS DETECTED.
FURTHER TESTING
MAY BE REQUIRED.P0000 0000————
INT/V TIM CONT-B1 P0011 0011 — —×EC-135
HO2S1 HTR (B1) P0031 0031××
×*4EC-138
HO2S1 HTR (B1) P0032 0032××
×*4EC-138
HO2S2 HTR (B1) P0037 0037××
×*4EC-144
HO2S2 HTR (B1) P0038 0038××
×*4EC-144
MAF SEN/CIRCUIT P0102 0102 — — —EC-149
MAF SEN/CIRCUIT P0103 0103 — — —EC-149
IAT SEN/CIRCUIT P0112 0112 — —×EC-156
IAT SEN/CIRCUIT P0113 0113 — —×EC-156
ECT SEN/CIRCUIT P0117 0117 — — —EC-162
ECT SEN/CIRCUIT P0118 0118 — — —EC-162
TP SEN 2/CIRC P0122 0122 — — —EC-168
TP SEN 2/CIRC P0123 0123 — — —EC-168
HO2S1 (B1) P0132 0132 —××EC-176
HO2S1 (B1) P0133 0133××
×*4EC-183
HO2S1 (B1) P0134 0134 —××EC-193
HO2S2 (B1) P0138 0138 —××EC-201
HO2S2 (B1) P0139 0139××
×*4EC-208
FUEL SYS-LEAN-B1 P0171 0171 — —×EC-216
FUEL SYS-RICH-B1 P0172 0172 — —×EC-223
TP SEN 1/CIRC P0222 0222 — — —EC-229
TP SEN 1/CIRC P0223 0223 — — —EC-229
MULTI CYL MISFIRE P0300 0300 — —×EC-237
CYL 1 MISFIRE P0301 0301 — —×EC-237
CYL 2 MISFIRE P0302 0302 — —×EC-237
CYL 3 MISFIRE P0303 0303 — —×EC-237
CYL 4 MISFIRE P0304 0304 — —×EC-237
KNOCK SEN/CIRC-B1 P0327 0327 — —×EC-242
KNOCK SEN/CIRC-B1 P0328 0328 — —×EC-242
CKP SEN/CIRCUIT P0335 0335 — —×EC-247
CMP SEN/CIRC-B1 P0340 0340 — —×EC-254
TW CATALYST SYS-B1 P0420 0420××
×*4EC-261

ON BOARD DIAGNOSTIC (OBD) SYSTEM
EC-55
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A sample of CONSULT-II display for DTC and 1st trip DTC is shown below. DTC or 1st trip DTC of a malfunc-
tion is displayed in “SELF-DIAGNOSTIC RESULTS” mode of CONSULT-II. Time data indicates how many
times the vehicle was driven after the last detection of a DTC.
If the DTC is being detected currently, the time data will be [0].
If a 1st trip DTC is stored in the ECM, the time data will be [1t].
FREEZE FRAME DATA AND 1ST TRIP FREEZE FRAME DATA
The ECM records the driving conditions such as fuel system status, calculated load value, engine coolant tem-
perature, short term fuel trim, long term fuel trim, engine speed, vehicle speed, base fuel schedule and intake
air temperature at the moment a malfunction is detected.
Data which are stored in the ECM memory, along with the 1st trip DTC, are called 1st trip freeze frame data.
The data, stored together with the DTC data, are called freeze frame data and displayed on CONSULT-II or
GST. The 1st trip freeze frame data can only be displayed on the CONSULT-II screen, not on the GST. For
details, see EC-105
.
Only one set of freeze frame data (either 1st trip freeze frame data or freeze frame data) can be stored in the
ECM. 1st trip freeze frame data is stored in the ECM memory along with the 1st trip DTC. There is no priority
for 1st trip freeze frame data and it is updated each time a different 1st trip DTC is detected. However, once
freeze frame data (2nd trip detection/MI on) is stored in the ECM memory, 1st trip freeze frame data is no
longer stored. Remember, only one set of freeze frame data can be stored in the ECM. The ECM has the fol-
lowing priorities to update the data.
For example, the EGR malfunction (Priority: 2) was detected and the freeze frame data was stored in the 2nd
trip. After that when the misfire (Priority: 1) is detected in another trip, the freeze frame data will be updated
from the EGR malfunction to the misfire. The 1st trip freeze frame data is updated each time a different mal-
function is detected. There is no priority for 1st trip freeze frame data. However, once freeze frame data is
stored in the ECM memory, 1st trip freeze data is no longer stored (because only one freeze frame data or 1st
trip freeze frame data can be stored in the ECM). If freeze frame data is stored in the ECM memory and freeze
frame data with the same priority occurs later, the first (original) freeze frame data remains unchanged in the
ECM memory.
Both 1st trip freeze frame data and freeze frame data (along with the DTCs) are cleared when the ECM mem-
ory is erased. Procedures for clearing the ECM memory are described in EC-63, "
HOW TO ERASE EMIS-
SION-RELATED DIAGNOSTIC INFORMATION" .
SYSTEM READINESS TEST (SRT) CODE
System Readiness Test (SRT) code is specified in Mode 1 of ISO 15031-5.
As part of an enhanced emissions test for Inspection & Maintenance (I/M), certain states require the status of
SRT be used to indicate whether the ECM has completed self-diagnosis of major emission systems and com-
ponents. Completion must be verified in order for the emissions inspection to proceed.
If a vehicle is rejected for a State emissions inspection due to one or more SRT items indicating “INCMP”, use
the information in this Service Manual to set the SRT to “CMPLT”.
In most cases the ECM will automatically complete its self-diagnosis cycle during normal usage, and the SRT
status will indicate “CMPLT” for each application system. Once set as “CMPLT”, the SRT status remains
“CMPLT” until the self-diagnosis memory is erased.
PBIB0911E
Priority Items
1Freeze frame data Misfire — DTC: P0300 - P0304
Fuel Injection System Function — DTC: P0171, P0172
2 Except the above items (Includes A/T related items)
3 1st trip freeze frame data

ON BOARD DIAGNOSTIC (OBD) SYSTEM
EC-65
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When there is an open circuit on MI circuit, the ECM can not warn the driver by lighting up MI when there is
trouble on engine control system.
Therefore, when electrical controlled throttle and part of ECM related diagnoses are continuously detected as
NG for 5 trips, ECM warns the driver that engine control system has trouble and MI circuit is open by means of
operating fail-safe function.
The fail-safe function also operates when above diagnoses except MI circuit are detected and demands the
driver to repair the trouble.
MI Flashing without DTC
If the ECM is in Diagnostic Test Mode II, MI may flash when engine is running. In this case, check ECM diag-
nostic test mode. EC-66, "
HOW TO SWITCH DIAGNOSTIC TEST MODE" .
How to switch the diagnostic test (function) modes, and details of the above functions are described later, EC-
66 .
The following emission-related diagnostic information is cleared when the ECM memory is erased.

Diagnostic trouble codes

1st trip diagnostic trouble codes

Freeze frame data

1st trip freeze frame data

System readiness test (SRT) codes

Test values
Diagnostic Test
ModeKEY and ENG.
StatusFunction Explanation of Function
Mode I Ignition switch in
ON position
Engine stoppedBULB CHECK This function checks the MI bulb for damage (blown, open
circuit, etc.).
If the MI does not come on, check MI circuit.
Engine running MALFUNCTION
WARNINGThis is a usual driving condition. When a malfunction is
detected twice in two consecutive driving cycles (two trip
detection logic), the MI will light up to inform the driver that
a malfunction has been detected.
The following malfunctions will light up or blink the MI in
the 1st trip.

Misfire (Possible three way catalyst damage)

One trip detection diagnoses
Mode II Ignition switch in
ON position
Engine stoppedSELF-DIAGNOSTIC
RESULTSThis function allows DTCs and 1st trip DTCs to be read.
Engine running HEATED OXYGEN SENSOR 1
MONITORThis function allows the fuel mixture condition (lean or
rich), monitored by heated oxygen sensor 1, to be read.
Engine operating condition in fail-safe mode Engine speed will not rise more than 2,500 rpm due to the fuel cut