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EC-242Revision: August 2007
DTC P0222, P0223 TP SENSOR
2004 QX56
Component InspectionUBS00H3O
THROTTLE POSITION SENSOR
1. Reconnect all harness connectors disconnected.
2. Perform EC-44, "
Throttle Valve Closed Position Learning" .
3. Turn ignition switch ON.
4. Set selector lever to D position.
5. Check voltage between ECM terminals 50 (TP sensor 1signal),
69 (TP sensor 2signal) and ground under the following condi-
tions.
6. If NG, replace electric throttle control actuator and go to the next
step.
7. Perform EC-44, "
Throttle Valve Closed Position Learning" .
8. Perform EC-44, "
Idle Air Volume Learning" .
Removal and InstallationUBS00H3P
ELECTRIC THROTTLE CONTROL ACTUATOR
Refer to EM-15, "INTAKE MANIFOLD" .
Terminal Accelerator pedal Voltage
50
(Throttle position sensor 1)Fully released More than 0.36V
Fully depressed Less than 4.75V
69
(Throttle position sensor 2)Fully released Less than 4.75V
Fully depressed More than 0.36V
PBIB1530E
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DTC P0300 - P0308 MULTIPLE CYLINDER MISFIRE, NO. 1 - 8 CYLINDER MIS-
FIRE
EC-243
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DTC P0300 - P0308 MULTIPLE CYLINDER MISFIRE, NO. 1 - 8 CYLINDER MIS-
FIRE
PFP:00000
On Board Diagnosis LogicUBS00H3Q
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 first 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 second 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 second trip. During this condition, the ECM monitors the CKP sen-
sor signal every 1,000 engine revolutions.
A misfire malfunction can be detected on any one cylinder or on multiple cylinders.
DTC Confirmation ProcedureUBS00H3R
CAUTION:
Always drive vehicle in safe manner according to traffic conditions and obey all traffic laws when driv-
ing.
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.
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 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
detected No. 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.
P0307
0307No. 7 cylinder misfire
detectedNo. 7 cylinder misfires.
P0308
0308No. 8 cylinder misfire
detectedNo. 8 cylinder misfires.
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EC-244Revision: August 2007
DTC P0300 - P0308 MULTIPLE CYLINDER MISFIRE, NO. 1 - 8 CYLINDER MIS-
FIRE
2004 QX56
WITH CONSULT-II
1. Turn ignition switch ON, and select “DATA MONITOR” mode
with CONSULT-II.
2. Start engine and warm it up to normal operating temperature.
3. Turn ignition switch OFF and wait at least 10 seconds.
4. Restart engine and let it idle for about 15 minutes.
5. If 1st trip DTC is detected, go to EC-244, "
Diagnostic Procedure"
.
NOTE:
If 1st trip DTC is not detected during above procedure, performing
the following procedure is advised.
1. Turn ignition switch OFF and wait at least 10 seconds.
2. Start engine and drive the vehicle under the similar conditions to (1st trip) Freeze Frame Data for a certain
time. Refer to the table below.
Hold the accelerator pedal as steady as possible.
The similar conditions to (1st trip) Freeze Frame Data means the vehicle operation that the following con-
ditions should be satisfied at the same time.
The time to driving varies according to the engine speed in the freeze frame data.
WITH GST
Follow the procedure “WITH CONSULT-II” above.
Diagnostic ProcedureUBS00H3S
1. CHECK FOR INTAKE AIR LEAK AND PCV HOSE
1. Start engine and run it at idle speed.
2. Listen for the sound of the intake air leak.
3. Check PCV hose connection.
OK or NG
OK >> GO TO 2.
NG >> Discover air leak location and repair.
2. CHECK FOR EXHAUST SYSTEM CLOGGING
Stop engine and visually check exhaust tube, three way catalyst and muffler for dents.
OK or NG
OK >> GO TO 3.
NG >> Repair or replace it.
PBIB0164E
Engine speed Engine speed in the freeze frame data ± 400 rpm
Vehicle speed Vehicle speed in the freeze frame data ± 10 km/h (6 MPH)
Engine coolant temperature
(T) conditionWhen the freeze frame data shows lower than 70 °C (158 °F),
T should be lower than 70 °C (158 °F).
When the freeze frame data shows higher than or equal to 70 °C (158 °F),
T should be higher than or equal to 70 °C (158 °F).
Engine speed Time
Around 1,000 rpm Approximately 10 minutes
Around 2,000 rpm Approximately 5 minutes
More than 3,000 rpm Approximately 3.5 minutes
Page 1436 of 3371
DTC P0300 - P0308 MULTIPLE CYLINDER MISFIRE, NO. 1 - 8 CYLINDER MIS-
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EC-245
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3. PERFORM POWER BALANCE TEST
With CONSULT-II
1. Perform “POWER BALANCE” in “ACTIVE TEST” mode.
2. Is there any cylinder which does not produce a momentary
engine speed drop?
Without CONSULT-II
When disconnecting each injector harness connector one at a time, is there any cylinder which does not pro-
duce a momentary engine speed drop?
Ye s o r N o
Yes >> GO TO 4.
No >> GO TO 7.
4. CHECK INJECTOR
Does each injector make an operating sound at idle?
Ye s o r N o
Yes >> GO TO 5.
No >> Check injector(s) and circuit(s). Refer to EC-595,
"INJECTOR CIRCUIT" .
PBIB0133E
BBIA0374E
PBIB1986E
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EC-246Revision: August 2007
DTC P0300 - P0308 MULTIPLE CYLINDER MISFIRE, NO. 1 - 8 CYLINDER MIS-
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2004 QX56
5. CHECK IGNITION SPARK
1. Turn ignition switch OFF.
2. Remove ignition coil assembly from rocker cover.
3. Remove spark plug from ignition coil assembly.
4. Connect a known-good spark plug to the ignition coil.
5. Disconnect all injector harness connectors.
6. Place end of spark plug against a suitable ground and crank engine.
7. Check for spark.
OK or NG
OK >> GO TO 6.
NG >> Check ignition coil, power transistor and their circuits.
Refer to EC-583, "
IGNITION SIGNAL" .
6. CHECK SPARK PLUGS
Remove the spark plugs and check for fouling, etc.
OK or NG
OK >> GO TO 7.
NG >> Repair or replace spark plug(s) with standard type
one(s). For spark plug type, refer to MA-17, "
Changing
Spark Plugs" .
7. CHECK COMPRESSION PRESSURE
Check compression pressure. Refer to EM-59, "
CHECKING COMPRESSION PRESSURE" .
OK or NG
OK >> GO TO 8.
NG >> Check pistons, piston rings, valves, valve seats and cylinder head gaskets.
SEF 5 75 Q
SEF 1 56 I
Standard:
1,520 kPa (15.5 kg/cm2 , 220 psi)/200 rpm
Minimum:
1,324 kPa (13.5 kg/cm
2 , 192 psi)/200 rpm
Difference between each
cylinder:98 kPa (1.0 kg/cm
2 , 14 psi)/200 rpm
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EC-247
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8. CHECK FUEL PRESSURE
1. Install all removed parts.
2. Release fuel pressure to zero. Refer to EC-46, "
FUEL PRESSURE RELEASE" .
3. Install fuel pressure gauge and check fuel pressure. Refer to EC-47, "
FUEL PRESSURE CHECK" .
OK or NG
OK >> GO TO 10.
NG >> GO TO 9.
9. DETECT MALFUNCTIONING PART
Check the following.
Fuel pump and circuit (Refer to EC-601, "FUEL PUMP CIRCUIT" .)
Fuel pressure regulator (Refer to EC-47, "FUEL PRESSURE CHECK" .)
Fuel lines
Fuel filter for clogging
>> Repair or replace.
10. CHECK IGNITION TIMING
Check the following items. Refer to EC-79, "
Basic Inspection" .
OK or NG
OK >> GO TO 11.
NG >> Follow the EC-79, "
Basic Inspection" . At idle: Approx. 350 kPa (3.57 kg/cm
2 , 51
psi)
Items Specifications
Target idle speed 650 ± 50 rpm (in P or N position)
Ignition timing 15 ± 5° BTDC (in P or N position)
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EC-248Revision: August 2007
DTC P0300 - P0308 MULTIPLE CYLINDER MISFIRE, NO. 1 - 8 CYLINDER MIS-
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2004 QX56
11 . CHECK A/F SENSOR 1 INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
1. Turn ignition switch OFF.
2. Disconnect A/F sensor 1 harness connector.
3. Disconnect ECM harness connector.
4. Check harness continuity between the following terminals.
Refer to Wiring Diagram, EC-431, "
Wiring Diagram" .
5. Check harness continuity between the following terminals and ground.
Refer to Wiring Diagram.
6. Also check harness for short to power.
OK or NG
OK >> GO TO 12.
NG >> Repair open circuit or short to ground or short to power in harness or connectors between ECM
and A/F sensor 1.
12. CHECK A/F SENSOR 1 HEATER (BANK 1)/(BANK 2)
Refer to EC-360, "
Component Inspection" .
OK or NG
OK >> GO TO 13.
NG >> Replace (malfunctioning) A/F sensor 1.
A/F sensor 1 terminal ECM terminal
Bank1116
275
535
656
Bank 2176
277
557
658
Continuity should exist.
Bank 1 Bank 2
A/F sensor 1 terminal ECM terminal A/F sensor 1 terminal ECM terminal
116176
275277
535557
656658
Continuity should not exist.
BBIA0376E
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13. CHECK MASS AIR FLOW SENSOR
With CONSULT-II
Check mass air flow sensor signal in “DATA MONITOR” mode with CONSULT-II.
With GST
Check mass air flow sensor signal in MODE 1 with GST.
OK or NG
OK >> GO TO 14.
NG >> Check connectors for rusted terminals or loose connections in the mass air flow sensor circuit or
engine grounds. Refer to EC-146, "
DTC P0101 MAF SENSOR" .
14. CHECK SYMPTOM MATRIX CHART
Check items on the rough idle symptom in EC-84, "
Symptom Matrix Chart" .
OK or NG
OK >> GO TO 15.
NG >> Repair or replace.
15. ERASE THE 1ST TRIP DTC
Some tests may cause a 1st trip DTC to be set.
Erase the 1st trip DTC from the ECM memory after performing the tests. Refer to EC-62, "
HOW TO ERASE
EMISSION-RELATED DIAGNOSTIC INFORMATION" .
>> GO TO 16.
16. CHECK INTERMITTENT INCIDENT
Refer to EC-127, "
TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT" .
>>INSPECTION END 3.0 - 9.0 g·m/sec: at idling
9.0 - 28.0 g·m/sec: at 2,500 rpm
3.0 - 9.0 g·m/sec: at idling
9.0 - 28.0 g·m/sec: at 2,500 rpm