EC-24
ENGINE CONTROL SYSTEM
Revision: 2006 November2007 350Z
ENGINE CONTROL SYSTEMPFP:23710
System DiagramNBS0002H
PBIB3466E
1. ECM 2. Data link connector 3. MIL
4. Ignition switch 5. Cooling fan 6. PNP switch
7. A/F sensor 1 8. Heated oxygen sensor 2 9.Exhaust valve timing control magnet
retarder
10.Exhaust valve timing control position
sensor11. PCV valve 12. Spark plug
13. Camshaft position sensor (PHASE) 14.Intake valve timing control solenoid
valve15. Fuel injector
16. Engine coolant temperature sensor 17. Fuel injector 18.Intake valve timing control solenoid
valve
19. Camshaft position sensor (PHASE) 20. Spark plug 21.Exhaust valve timing control position
sensor
TROUBLE DIAGNOSIS
EC-81
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TROUBLE DIAGNOSISPFP:00004
Trouble Diagnosis IntroductionNBS0003D
INTRODUCTION
The engine has an ECM to control major systems such as fuel con-
trol, ignition control, idle air control system, etc. The ECM accepts
input signals from sensors and instantly drives actuators. It is essen-
tial that both input and output signals are proper and stable. At the
same time, it is important that there are no malfunctions such as vac-
uum leaks, fouled spark plugs, or other malfunctions with the engine.
It is much more difficult to diagnose an incident that occurs intermit-
tently rather than continuously. Most intermittent incidents are
caused by poor electric connections or improper wiring. In this case,
careful checking of suspected circuits may help prevent the replace-
ment of good parts.
A visual check only may not find the cause of the incidents. A road
test with CONSULT-III (or GST) or a circuit tester connected should
be performed. Follow the WORK FLOW on EC-82
.
Before undertaking actual checks, take a few minutes to talk with a
customer who approaches with a driveability complaint. The cus-
tomer can supply good information about such incidents, especially
intermittent ones. Find out what symptoms are present and under
what conditions they occur. A DIAGNOSTIC WORKSHEET like the
example on EC-86
should be used.
Start your diagnosis by looking for conventional malfunctions first.
This will help troubleshoot driveability malfunctions on an electroni-
cally controlled engine vehicle.
MEF036D
SEF233G
SEF234G
EC-94
TROUBLE DIAGNOSIS
Revision: 2006 November2007 350Z
Engine Control Component Parts LocationNBS0003I
1. IPDM E/R 2. Mass air flow sensor (with intake air
temperature sensor) (bank 1)3. Refrigerant pressure sensor
4. Cooling fan motor-2 5. Intake valve timing control solenoid
valve6. Exhaust valve timing control magnet
retarder
7. Cooling fan motor-1 8. Mass air flow sensor (with intake air
temperature sensor) (bank 2)9. Ignition coil (with power transistor)
and spark plug (bank 2)
10. Electric throttle control actuator
(bank 2)11. A/F sensor 1 (bank 2) 12. Exhaust valve timing control position
sensor
13. Camshaft position sensor (PHASE) 14. Fuel injector (bank 2) 15. Engine coolant temperature sensor
16. Knock sensor 17. EVAP canister purge volume con-
trol solenoid valve18. Fuel injector (bank 1)
19. Ignition coil (with power transistor)
and spark plug (bank 1)20. EVAP service port 21. A/F sensor 1 (bank 1)
22. Crankshaft position sensor (POS) 23. Electric throttle control actuator
(bank 1)
PBIB3474E
EC-124
TROUBLE DIAGNOSIS
Revision: 2006 November2007 350Z
ACTIVE TEST MODE
Test Item
*: Leaving cooling fan “OFF” with CONSULT-III while engine is running may cause the engine to overheat.TEST ITEM CONDITION JUDGEMENT CHECK ITEM (REMEDY)
FUEL INJEC-
TION
Engine: Return to the original
trouble condition
Change the amount of fuel injec-
tion using CONSULT-III.If trouble symptom disappears, see
CHECK ITEM.
Harness and connectors
Fuel injector
Air fuel ratio (A/F) sensor 1
IGNITION TIM-
ING
Engine: Return to the original
trouble condition
Timing light: Set
Retard the ignition timing using
CONSULT-III.If trouble symptom disappears, see
CHECK ITEM.
Perform Idle Air Volume Learning.
POWER BAL-
ANCE
Engine: After warming up, idle
the engine.
A/C switch OFF
Shift lever: P or N (A/T), Neutral
(M/T)
Cut off each fuel injector signal
one at a time using CONSULT-III.Engine runs rough or dies.
Harness and connectors
Compression
Fuel injector
Power transistor
Spark plug
Ignition coil
COOLING FAN
*
Ignition switch: ON
Turn the cooling fan “HI”, “LOW”
and “OFF” using CONSULT-III.Cooling fan moves and stops.
Harness and connectors
Cooling fan motor
IPDM E/R
ENG COOLANT
TEMP
Engine: Return to the original
trouble condition
Change the engine coolant tem-
perature using CONSULT-III.If trouble symptom disappears, see
CHECK ITEM.
Harness and connectors
Engine coolant temperature sen-
sor
Fuel injector
FUEL PUMP
RELAY
Ignition switch: ON
(Engine stopped)
Turn the fuel pump relay “ON”
and “OFF” using CONSULT-III
and listen to operating sound.Fuel pump relay makes the operat-
ing sound.Harness and connectors
Fuel pump relay
PURG VOL
CONT/V
Engine: After warming up, run
engine at 1,500 rpm.
Change the EVAP canister purge
volume control solenoid valve
opening percent using CON-
SULT-III.Engine speed changes according to
the opening percent.Harness and connectors
Solenoid valve
FUEL/T TEMP
SEN
Change the fuel tank temperature using CONSULT-III.
VENT CON-
TROL/V
Ignition switch: ON
(Engine stopped)
Turn solenoid valve “ON” and
“OFF” with the CONSULT-III and
listen to operating sound.Solenoid valve makes an operating
sound.Harness and connectors
Solenoid valve
INT V/T ASSIGN
ANGLE
Engine: Return to the original
trouble condition
Change intake valve timing using
CONSULT-III.If trouble symptom disappears, see
CHECK ITEM.
Harness and connectors
Intake valve timing control sole-
noid valve
EXH V/T ASSIGN
ANGLE
Engine: Return to the original
trouble condition
Change exhaust valve timing
using CONSULT-III.If trouble symptom disappears, see
CHECK ITEM.
Harness and connectors
Exhaust valve timing control mag-
net retarder
DTC P0300 - P0306 MULTIPLE CYLINDER MISFIRE, NO. 1 - 6 CYLINDER MIS-
FIRE
EC-371
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DTC P0300 - P0306 MULTIPLE CYLINDER MISFIRE, NO. 1 - 6 CYLINDER MIS-
FIRE
PFP:00000
On Board Diagnosis LogicNBS0007U
When a misfire occurs, engine speed will fluctuate. If the engine speed fluctuates enough to cause the crank-
shaft position (CKP) sensor (POS) signal to vary, ECM can determine that a misfire is occurring.
The misfire detection logic consists of the following two conditions.
1. One Trip Detection Logic (Three Way Catalyst Damage)
On the 1st trip that a misfire condition occurs that can damage the three way catalyst (TWC) due to over-
heating, the MIL will blink.
When a misfire condition occurs, the ECM monitors the CKP sensor signal every 200 engine revolutions
for a change.
When the misfire condition decreases to a level that will not damage the TWC, the MIL will turn off.
If another misfire condition occurs that can damage the TWC on a 2nd trip, the MIL will blink.
When the misfire condition decreases to a level that will not damage the TWC, the MIL will remain on.
If another misfire condition occurs that can damage the TWC, the MIL will begin to blink again.
2. Two Trip Detection Logic (Exhaust quality deterioration)
For misfire conditions that will not damage the TWC (but will affect vehicle emissions), the MIL will only
light when the misfire is detected on a 2nd trip. During this condition, the ECM monitors the CKP sensor
signal every 1,000 engine revolutions.
A misfire malfunction can be detected on any one cylinder or on multiple cylinders.
Sensor Input Signal to ECM ECM function
Crankshaft position sensor (POS) Engine speed On board diagnosis of misfire
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P0300
0300Multiple cylinder misfire
detectedMultiple cylinder misfire.
Improper spark plug
Insufficient compression
Incorrect fuel pressure
The fuel injector circuit is open or
shorted
Fuel injector
Intake air leak
The ignition signal circuit is open or
shorted
Lack of fuel
Signal plate
Air fuel ratio (A/F) sensor 1
Incorrect PCV hose connection P0301
0301No.1 cylinder misfire
detectedNo. 1 cylinder misfires.
P0302
0302No. 2 cylinder misfire
detectedNo. 2 cylinder misfires.
P0303
0303No. 3 cylinder misfire
detectedNo. 3 cylinder misfires.
P0304
0304No. 4 cylinder misfire
detectedNo. 4 cylinder misfires.
P0305
0305No. 5 cylinder misfire
detectedNo. 5 cylinder misfires.
P0306
0306No. 6 cylinder misfire
detectedNo. 6 cylinder misfires.
EC-374
DTC P0300 - P0306 MULTIPLE CYLINDER MISFIRE, NO. 1 - 6 CYLINDER MIS-
FIRE
Revision: 2006 November2007 350Z
5. CHECK FUNCTION OF IGNITION COIL-I
CAUTION:
Do the following procedure in the place where ventilation is good without the combustible.
1. Turn ignition switch OFF.
2. Reconnect all harness connectors disconnected.
3. Remove fuel pump fuse in IPDM E/R to release fuel pressure.
NOTE:
Do not use CONSULT-III to release fuel pressure, or fuel pres-
sure applies again during the following procedure.
4. Start engine.
5. After engine stalls, crank it two or three times to release all fuel
pressure.
6. Turn ignition switch OFF.
7. Remove all ignition coil harness connectors to avoid the electri-
cal discharge from the ignition coils.
8. Remove ignition coil and spark plug of the cylinder to be
checked.
9. Crank engine for 5 seconds or more to remove combustion gas in the cylinder.
10. Connect spark plug and harness connector to ignition coil.
11. Fix ignition coil using a rope etc. with gap of 13 - 17 mm
between the edge of the spark plug and grounded metal portion
as shown in the figure.
12. Crank engine for about 3 seconds, and check whether spark is
generated between the spark plug and the grounded metal por-
tion.
CAUTION:
Do not approach to the spark plug and the ignition coil
within 50cm. Be careful not to get an electrical shock
while checking, because the electrical discharge voltage
becomes 20kV or more.
It might cause to damage the ignition coil if the gap of more than 17 mm is taken.
NOTE:
When the gap is less than 13 mm, the spark might be generated even if the coil is malfunctioning.
OK or NG
OK >> GO TO 9.
NG >> GO TO 6.
6. CHECK FUNCTION OF IGNITION COIL-II
1. Turn ignition switch OFF.
2. Disconnect spark plug and connect a known-good spark plug.
3. Crank engine for about 3 seconds, and recheck whether spark is generated between the spark plug and
the grounded metal portion.
OK or NG
OK >> GO TO 7.
NG >> Check ignition coil, power transistor and their circuits. Refer to EC-698, "
IGNITION SIGNAL" . Spark should be generated.
PBIB2206E
PBIB2325E
Spark should be generated.
DTC P0300 - P0306 MULTIPLE CYLINDER MISFIRE, NO. 1 - 6 CYLINDER MIS-
FIRE
EC-375
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Revision: 2006 November2007 350Z
7. CHECK SPARK PLUG
Check the initial spark plug for fouling, etc.
OK or NG
OK >> Replace spark plug(s) with standard type one(s). For
spark plug type, refer to MA-18, "
Changing Spark Plugs
(Iridium-Tipped Type)" .
NG >> 1. Repair or clean spark plug.
2. GO TO 8.
8. CHECK FUNCTION OF IGNITION COIL-III
1. Reconnect the initial spark plugs.
2. Crank engine for about 3 seconds, and recheck whether spark is generated between the spark plug and
the grounded portion.
OK or NG
OK >>INSPECTION END
NG >> Replace spark plug(s) with standard type one(s). For spark plug type, refer to MA-18, "
Changing
Spark Plugs (Iridium-Tipped Type)" .
9. CHECK COMPRESSION PRESSURE
Check compression pressure. Refer to EM-89, "
CHECKING COMPRESSION PRESSURE" .
OK or NG
OK >> GO TO 10.
NG >> Check pistons, piston rings, valves, valve seats and cylinder head gaskets.
10. CHECK FUEL PRESSURE
1. Install all removed parts.
2. Release fuel pressure to zero. Refer to EC-79, "
FUEL PRESSURE RELEASE" .
3. Install fuel pressure gauge and check fuel pressure. Refer to EC-80, "
FUEL PRESSURE CHECK" .
OK or NG
OK >> GO TO 12.
NG >> GO TO 11.
11 . DETECT MALFUNCTIONING PART
Check the following.
Fuel pump and circuit (Refer to EC-691, "FUEL PUMP" .)
Fuel pressure regulator (Refer to EC-80, "FUEL PRESSURE CHECK" .)
Fuel lines (Refer tor FL-3, "Checking Fuel Lines" .)
Fuel filter for clogging
>> Repair or replace.
SEF156I
Spark should be generated.
At idle: Approximately 350 kPa (3.57 kg/cm
2 , 51 psi)
EC-406
DTC P0420, P0430 THREE WAY CATALYST FUNCTION
Revision: 2006 November2007 350Z
DTC P0420, P0430 THREE WAY CATALYST FUNCTIONPFP:20905
On Board Diagnosis LogicNBS0008K
The ECM monitors the switching frequency ratio of air fuel ratio (A/F) sensor 1 and heated oxygen sensor 2.
A three way catalyst 1 with high oxygen storage capacity will indicate a low switching frequency of heated oxy-
gen sensor 2. As oxygen storage capacity decreases, the heated oxygen sensor 2 switching frequency will
increase.
When the frequency ratio of air fuel ratio (A/F) sensor 1 and heated oxygen sensor 2 approaches a specified
limit value, the three way catalyst 1 malfunction is diagnosed.
DTC Confirmation ProcedureNBS0008L
NOTE:
If DTC Confirmation Procedure has been previously conducted, always turn ignition switch OFF and wait at
least 10 seconds before conducting the next test.
WITH CONSULT-III
TESTING CONDITION:
Do not hold engine speed for more than the specified minutes below.
1. Turn ignition switch ON and select “DATA MONITOR” mode with CONSULT-III.
2. Start engine and warm it up to the normal operating temperature.
3. Turn ignition switch OFF and wait at least 10 seconds.
4. Start engine and keep the engine speed between 3,500 and 4,000 rpm for at least 1 minute under no load.
5. Let engine idle for 1 minute.
6. Make sure that “COOLAN TEMP/S” indicates more than 70°C (158°F).
If not, warm up engine and go to next step when “COOLAN TEMP/S” indication reaches to 70°C (158°F).
7. Open engine hood.
8. Select “DTC & SRT CONFIRMATION” then “SRT WORK SUPPORT” mode with CONSULT-III.
9. Rev engine up to 2,000 to 3,000 rpm and hold it for 3 consecutive minutes then release the accelerator
pedal completely.
If “INCMP” of “CATALYST” changed to “CMPLT”, go to step 12.
10. Wait 5 seconds at idle.
11. Rev engine up to 2,000 to 3,000 rpm and maintain it until “INCMP” of “CATALYST” changes to “CMPLT” (It
will take approximately 5 minutes).
If not “CMPLT”, stop engine and cool it down to less than 70°C (158°F) and then retest from step 1.
12. Select “SELF-DIAG RESULTS” mode with CONSULT-III.
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P0420
0420
(Bank 1)
Catalyst system effi-
ciency below threshold
Three way catalyst 1 does not operate prop-
erly.
Three way catalyst 1 does not have enough
oxygen storage capacity.
Three way catalyst 1
Exhaust tube
Intake air leaks
Fuel injector
Fuel injector leaks
Spark plug
Improper ignition timing P0430
0430
(Bank 2)
PBIB1923E