Inspection Procedure

HINT:

If DTCs besides misfire DTCs are memorized simultaneously, troubleshoot the non-misfire DTCs first.
Read freeze frame data using the intelligent tester or the OBD II scan tool. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, it is useful for determining whether the vehicle was running or stopped, the engine was warmed up or not, the air-fuel ratio was lean or rich, etc. at the time of the malfunction.
If the misfire does not occur when the vehicle is brought to the workshop, the misfire can be confirmed by reproducing the condition of the freeze frame data. Also, after finishing the repair, confirm that there is no misfire (see CONFIRMATION DRIVING PATTERN ).
On 6 and 8 cylinder engines, cylinder specific misfire fault codes are disabled at high engine speeds. If the misfire starts in a high engine speed area or the misfire occurs only in a high engine speed area, only the general fault code P0300 will be stored.
When only a general misfire fault code like P0300 is stored:
1. Erase the general misfire fault code from the ECM using the intelligent tester or OBD II scan tool.
2. Start the engine and drive the confirmation pattern.
3. Read the value of the misfire ratio for each cylinder. Or read the DTC.
4. Perform repairs on the cylinder that has a high misfire ratio. Or repair the cylinder indicated by the DTC.
5. After finishing repairs, drive the confirmation pattern again and confirm that no misfire occurs.
When either of SHORT FT #1, LONG FT #1, SHORT FT #2 or LONG FT #2 in the freeze frame data is over the range of +-20 %, there is a possibility that the air-fuel ratio is becoming RICH (-20 % or less) or LEAN (+20 % or more).
When COOLANT TEMP in the freeze frame data is less than 80°C (176°F), there is a possibility of misfire only during engine warm-up.
If the misfire cannot be reproduced, the following reasons may apply: 1) the vehicle has low fuel, 2) improper fuel is being used, and 3) the ignition plug is contaminated.
Be sure to check the value on the misfire counter after the repair.

CHECK OTHER DTC OUTPUT (IN ADDITION TO MISFIRE DTCS)

Read the DTC using the intelligent tester or the OBD II scan tool.

Result

OTHER DTC OUTPUT (IN ADDITION TO MISFIRE DTCS)

Display (DTC Output)	Proceed to
Only "P0300, P0301, P0302, P0303, P0304, P0305 and/or P0306" are output A	"P0300, P0301, P0302, P0303, P0304, P0305 or P0306" and other DTCs are output B

HINT:

If any other codes besides "P0300, P0301, P0302, P0303, P0304, P0305 or P0306" are output, perform the troubleshooting for those DTCs first.

B : GO TO RELEVANT DIAGNOSTIC TROUBLE CODE CHART

A : Go to next step

CHECK WIRE HARNESS, CONNECTOR AND VACUUM HOSE IN ENGINE ROOM
1. Check the connection conditions of the wire harness and connector.
2. Check for the disconnection, piping and break of the vacuum hose.
NG : REPAIR OR REPLACE, THEN CONFIRM THAT THERE IS NO MISFIRE

OK : Go to next step
CHECK PCV HOSE
NG : REPAIR OR REPLACE PCV HOSE

OK : Go to next step

READ VALUE OF INTELLIGENT TESTER OR OBD II SCAN TOOL (NUMBER OF MISFIRE)

Connect the intelligent tester or the OBD II scan tool to the DLC3.
Turn the ignition switch ON and push the intelligent tester or the OBD II scan tool main switch ON.
Start the engine.
Select the item "DIAGNOSIS/ENHANCED OBD II/DATA LIST/ALL/CYL#1 - CYL#6".
Read the number of misfire on the intelligent tester or the OBD II scan tool.

HINT:

When a misfire is not reproduced, be sure to branch below based on the stored DTC.

Result

NUMBER OF MISFIRE

High Misfire Rate Cylinder	Proceed to
1 or 2 cylinders	A
More than 3 cylinders	B

B : GO TO STEP 15

A : Go to next step

CHECK SPARK PLUG AND SPARK OF MISFIRING CYLINDER

Remove the ignition coil assembly.
Remove the spark plug.

Check the spark plug type.

Recommended spark plug:

RECOMMENDED SPARK PLUG

DENSO made	SK20R11
NGK made	IFR6A11

Fig 1: Checking Spark Plug And Spark Of Misfiring Cylinder

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Check the spark plug electrode gap.
Electrode gap: 1.0 to 1.1 mm (0.039 to 0.043 in.)

Maximum electrode gap: 1.3 mm (0.051 in.)

NOTE: If adjusting the gap of a new spark plug, bend only the base the ground electrode. Do not touch the tip. Never attempt to adjust the gap on a used plug.
Check the electrode for carbon deposits.
Perform a spark test.
CAUTION: Absolutely disconnect the each injector connectors.

NOTE: Do not crank the engine for more than 2 seconds.
1. Install the spark plug to the ignition coil, and connect the ignition coil connector.
2. Disconnect the injector connector.
3. Ground the spark plug.
4. Check if spark occurs while the engine is being cranked.
Standard: Spark jumps across electrode gap.
Reinstall the spark plug.
Reinstall the ignition coil assembly.

OK : GO TO STEP 8

NG : Go to next step

CHANGE NORMAL SPARK PLUG AND CHECK SPARK OF MISFIRING CYLINDER
1. Change to the normal spark plug.
2. Perform a spark test.
CAUTION: Absolutely disconnect each injector connector.

NOTE: Do not crank the engine for more than 2 seconds.
1. Install the spark plug to the ignition coil, and connect the ignition coil connector.
2. Disconnect the injector connector.
3. Ground the spark plug.
4. Check if spark occurs while the engine is being cranked.
Standard: Spark jumps across electrode gap.

OK : REPLACE SPARK PLUG

NG : Go to next step
CHECK HARNESS AND CONNECTOR OF MISFIRING CYLINDER (IGNITION COIL - ECM)
OK : REPLACE IGNITION COIL ASSEMBLY (THEN CONFIRM THAT THERE IS NO MISFIRE)

NG : REPAIR OR REPLACE HARNESS OR CONNECTOR

INSPECT ECM TERMINAL OF MISFIRING CYLINDER (#10, #20, #30, #40, #50 OR #60 VOLTAGE)

Turn the ignition switch ON.
Measure the voltage between the applicable terminals of the E8 and E9 ECM connectors.

Standard voltage

ECM TERMINAL OF MISFIRING CYLINDER (#10, #20, #30, #40, #50 OR #60 VOLTAGE)

Tester Connection	Specified Condition
#10 (E8-1) - E01 (E8-7)	9 to 14 V
#20 (E8-2) - E01 (E8-7)	9 to 14 V
#30 (E8-3) - E01 (E8-7)	9 to 14 V
#40 (E8-4) - E01 (E8-7)	9 to 14 V
#50 (E8-5) - E01 (E8-7)	9 to 14 V
#60 (E9-31) - E01 (E8-7)	9 to 14 V

Fig 2: Inspecting ECM Terminal Of Misfiring Cylinder (#10, #20, #30, #40, #50 Or #60 Voltage)

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

OK : GO TO STEP 11

NG : Go to next step

INSPECT FUEL INJECTOR RESISTANCE OF MISFIRING CYLINDER
1. Inspect the fuel injector. (See INSPECTION )
NG : REPLACE FUEL INJECTOR ASSEMBLY

OK : Go to next step

CHECK HARNESS AND CONNECTOR OF MISFIRING CYLINDER (INJECTOR - ECM, INJECTOR - IGNITION SWITCH)

Check the harness and the connector between the injector connector and the ECM connector.

Disconnect the I8, I9, I10, I11, I12 or I13 injector connector.
Disconnect the E8 or E9 ECM connector.

Check the resistance between the wire harness side connectors.

Standard resistance

INJECTOR - ECM

Tester Connection	Specified Condition
Injector (I8-1) - #10 (E8-1)	Below 1 Ω
Injector (I9-1) - #20 (E8-2)	Below 1 Ω
Injector (I10-1) - #30 (E8-3)	Below 1 Ω
Injector (I11-1) - #40 (E8-4)	Below 1 Ω
Injector (I12-1) - #50 (E8-5)	Below 1 Ω
Injector (I13-1) - #60 (E9-3)	Below 1 Ω
Injector (I8-1) or #10 (E8-1) - Body ground	10 kΩ or higher
Injector (I9-1) or #20 (E8-2) - Body ground	10 kΩ or higher
Injector (I10-1) or #30 (E8-3) - Body ground	10 kΩ or higher
Injector (I11-1) or #40 (E8-4) - Body ground	10 kΩ or higher
Injector (I12-1) or #50 (E8-5) - Body ground	10 kΩ or higher
Injector (I13-1) or #60 (E9-3) - Body ground	10 kΩ or higher

Reconnect the injector connector.
Reconnect the ECM connector.

Check the harness and the connector between the injector connector and the ignition switch connector.

Check the INJ fuse.
- Remove the INJ fuse from the instrument panel J/B.
- Measure the resistance of the INJ fuse.
  Standard resistance: Below 1 Ω
- Reinstall the INJ fuse.
Disconnect the I8, I9, I10, I11, I12 or I13 injector connector.
Disconnect the I14 ignition switch connector.

Check the resistance between the wire harness side connectors.

Standard resistance

INJECTOR - IGNITION SWITCH

Tester Connection	Specified Condition
Injector (I8-2) - IG2 (I14-6)	Below 1 Ω
Injector (I9-2) - IG2 (I14-6)	Below 1 Ω
Injector (I10-2) - IG2 (I14-6)	Below 1 Ω
Injector (I11-2) - IG2 (I14-6)	Below 1 Ω
Injector (I12-2) - IG2 (I14-6)	Below 1 Ω
Injector (I13-2) - IG2 (I14-6)	Below 1 Ω
Injector (I8-2) or IG2 (I14-6) - Body ground	10 kΩ or higher
Injector (I9-2) or IG2 (I14-6) - Body ground	10 kΩ or higher
Injector (I10-2) or IG2 (I14-6) - Body ground	10 kΩ or higher
Injector (I11-2) or IG2 (I14-6) - Body ground	10 kΩ or higher
Injector (I12-2) or IG2 (I14-6) - Body ground	10 kΩ or higher
Injector (I13-2) or IG2 (I14-6) - Body ground	10 kΩ or higher

Fig 3: Checking Harness And Connector Of Misfiring Cylinder (Injector - ECM, Injector - Ignition Switch)

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Reconnect the injector connector.
Reconnect the ignition switch connector.

NG : REPAIR OR REPLACE HARNESS OR CONNECTOR

OK : Go to next step

INSPECT FUEL INJECTOR INJECTION AND VOLUME OF MISFIRING CYLINDER
1. Inspect the fuel injector. (See INSPECTION )
NG : REPLACE FUEL INJECTOR ASSEMBLY

OK : Go to next step
CHECK CYLINDER COMPRESSION PRESSURE OF MISFIRING CYLINDER
1. Inspect cylinder compression pressure. (See ON-VEHICLE INSPECTION )
NG : REPAIR OR REPLACE CYLINDER HEAD ASSEMBLY

OK : Go to next step
CHECK VALVE CLEARANCE OF MISFIRING CYLINDER
1. Inspect the valve clearance. (See VALVE CLEARANCE )
NG : ADJUST VALVE CLEARANCE

OK : Go to next step
SWITCH STEP BY NUMBER OF MISFIRE CYLINDER (REFER RESULT OF STEP 4 )
HINT:
- If the result of step 4 is "1 or 2 cylinders", proceed to A.
- If the result of step 4 is "more than 3 cylinders", proceed to B.
B : CHECK FOR INTERMITTENT PROBLEMS

A : Go to next step
CHECK VALVE TIMING
1. Check for looseness or jumping teeth of the timing belt (See TIMING BELT ).
NG : ADJUST VALVE TIMING (REPAIR OR REPLACE TIMING BELT)

OK : Go to next step
CHECK FUEL PRESSURE
1. Check the fuel pressure (See ON-VEHICLE INSPECTION ).
Standard: 304 to 343 kPa (3.1 to 3.5 kgf/cm ² , 44.1 to 49.7 psi)

NG : CHECK AND REPLACE FUEL PUMP, PRESSURE REGULATOR, FUEL PIPE LINE AND FILTER

OK : Go to next step

READ VALUE OF INTELLIGENT TESTER OR OBD II SCAN TOOL (INTAKE AIR TEMPERATURE AND MASS AIR FLOW RATE)

Connect the intelligent tester or the OBD II scan tool to the DLC3.
Turn the ignition switch ON.
Check the intake air temperature.
1. Select the item "DIAGNOSIS/ENHANCED OBD II/DATA LIST/ALL/INTAKE AIR" and read its value displayed on the intelligent tester or the OBD II scan tool.
Temperature: Equivalent to ambient temperature
Check the air flow rate.

Select the item "DIAGNOSIS/ENHANCED OBD II/DATA LIST/ALL/MAF" and read its value displayed on the intelligent tester or the OBD II scan tool.

Standard

INTAKE AIR TEMPERATURE AND MASS AIR FLOW RATE

Condition	Air Flow Rate (gm/s)
Ignition switch ON (do not start engine)	0
Idling	4 to 6
Running without load (2,500 rpm)	13 to 20
Idling to quickly accelerating	Air flow rate fluctuates

NG : REPLACE MASS AIR FLOW SENSOR

OK : Go to next step

INSPECT ENGINE COOLANT TEMPERATURE SENSOR (RESISTANCE)

Remove the engine coolant temperature sensor.

Measure the resistance between the terminals.

Standard resistance

ENGINE COOLANT TEMPERATURE SENSOR (RESISTANCE)

Tester Connection	Specified Condition
1-2	2.32 to 2.59 kΩ (20°C (68°F))
1-2	0.310 to 0.326 kΩ (80°C (176°F))

NOTE: In case of checking the engine coolant temperature sensor in the water, be careful not to allow water to go into the terminals. After checking, dry the sensor.

HINT:

Alternate procedure: Connect an ohmmeter to the installed engine coolant temperature sensor and read the resistance. Use an infrared thermometer to measure the engine temperature in the immediate vicinity of the sensor. Compare these values to the resistance/temperature graph. Change the engine temperature (warm up or allow to cool down) and repeat the test.

Reinstall the engine coolant temperature sensor.

Fig 4: Resistance To Temperature Graph

NG : REPLACE ENGINE COOLANT TEMPERATURE SENSOR

OK : Go to next step

SWITCH STEP BY NUMBER OF MISFIRING CYLINDER (REFER RESULT OF STEP 4)

HINT:

If the result of step 4 is "1 or 2 cylinders", proceed to A.
If the result of step 4 is "more than 3 cylinders", proceed to B.

B : GO TO STEP 5

A : CHECK FOR INTERMITTENT PROBLEMS