DESCRIPTION

Random misfire detected

DETECTION CONDITION

Determination conditions

• Any one of the following conditions is met:

• The misfire rate for every 200 rotations of the crankshaft exceeds the specified value (misfire which may damage catalytic converter).

• The misfire rate for every 1,000 rotations of the crankshaft exceeds the specified value (misfire going against emission regulations).

Preconditions

• Battery voltage: 9—18 V^*1

• Engine speed: 500—6,700 rpm^*1

• Engine coolant temperature: 20 °C {68 °F} or more^*1

• Not cranking

• Not stalling

• Fuel-cut control not implemented

• Crankshaft installation tolerance learning completed

• Engine condition is stabilized (not directly after gear change)

• ^*1: Value can be verified by displaying PIDs using the M-MDS.

Malfunction determination period

• 200 rotations of crankshaft (misfire which may damage catalytic converter)

• 1,000 rotations of crankshaft (misfire going against emission regulations)

Drive cycle

• 2

Self test type

• CMDTC self test

Sensor used

• CKP sensor

• MAF sensor

• MAP sensor

FAIL-SAFE FUNCTION

• Limits intake air amount

• Implement fuel-cut control (if the catalytic converter may be damaged, perform fuel-cut on cylinder misfiring the most).

VEHICLE STATUS WHEN DTCs ARE OUTPUT

• Misfiring which may damage catalytic converter (number of drive cycles: 1):

• Check engine light flashes and pending code is recorded

• Drive cycle directly after above drive cycle (number of drive cycles: 2):

• Malfunction determined: check engine light is illuminated

• Normal is determined: Pending code cleared

• Rough idling, poor acceleration, stalling

POSSIBLE CAUSE

• Improper operation of ignition system

• Spark plug malfunction

• Ignition coil related wiring harness or connector malfunction

• Ignition coil malfunction

• Fuel injector malfunction

• Improper operation of fuel injector

• Fuel injector related wiring harness malfunction

• Erratic signal to PCM

• CKP sensor signal malfunction

• ECT sensor No.1 signal malfunction

• MAF sensor signal malfunction

• MAP sensor signal malfunction

• IAT sensor No.1 signal malfunction

• APP sensor signal malfunction

• TP sensor signal malfunction

• VSS signal malfunction

• Related connector or terminals malfunction

• Related wiring harness malfunction

• Poor drive belt assembly or adhesion of oil

• Drive belt auto tensioner malfunction

• Air leakage from intake air system (between intake manifold and cylinder head)

• Engine malfunction

• Insufficient engine compression

• Engine coolant leakage to combustion chamber

• PCM malfunction

Item

Definition

Unit

Condition/Specification

APP1

Accelerator pedal opening angle (absolute value) input from APP sensor No.1

%

• Accelerator pedal released: Approx. 15.29%

• Accelerator pedal fully depressed: Approx. 90.98%

APP sensor No.1 voltage

V

• Accelerator pedal released: Approx. 0.77 V

• Accelerator pedal fully depressed: Approx. 4.55 V

APP2

Accelerator pedal opening angle (absolute value) input from APP sensor No.2

%

• Accelerator pedal released: Approx. 7.84%

• Accelerator pedal fully depressed: Approx. 45.49%

APP sensor No.2 voltage

V

• Accelerator pedal released: Approx. 0.38 V

• Accelerator pedal fully depressed: Approx. 2.27 V

ECT

Engine coolant temperature input from ECT sensor No.1

°C, °F

• Displays ECT

ECT sensor No.1 voltage

V

Ignition switched ON (engine off)

• ECT is 92 °C {198 °F}: Approx. 0.65 V

Idle (after warm up)

• ECT is 93 °C {199 °F}: Approx. 0.64 V

Racing (Engine speed is 2,000 rpm)

• ECT is 92 °C {198 °F}: Approx. 0.66 V

Racing (Engine speed is 4,000 rpm)

• ECT is 93 °C {199 °F}: Approx. 0.64 V

IAT

Intake air temperature (No.1) input from IAT sensor No.1

°C, °F

• Displays IAT (No.1)

IAT sensor No.1 voltage

V

• IAT is 60 °C {140 °F}: Approx. 1.13 V

• IAT is 63 °C {145 °F}: Approx. 1.07 V

• IAT is 65 °C {149 °F}: Approx. 1.01 V

MAF

Mass air flow input from MAF sensor

g/Sec

• Displays MAF

MAF sensor voltage

V

• Ignition switched ON (engine off) (MAF: 0.39 g/s {0.052 lb/min}): Approx. 0.72 V (ECT is 89 °C {192 °F})

• Idle (after warm up) (MAF: 4.29 g/s {0.567 lb/min}): Approx. 1.15 V (ECT is 88 °C {190 °F})

• Racing (engine speed is 2,000 rpm) (MAF: 4.32 g/s {0.571 lb/min}): Approx. 1.15 V (ECT is 89 °C {192 °F})

• Racing (engine speed is 4,000 rpm) (MAF: 12.71 g/s {1.681 lb/min}): Approx. 1.66 V (ECT is 89 °C {192 °F})

MAP

Manifold absolute pressure input from MAP sensor

KPa , mBar , psi, in H20

• Displays MAP

MAP_V

MAP sensor voltage

V

• Ignition switched ON (engine off) (MAP:101 kPa {1.03 kgf/cm², 14.6 psi}): Approx. 4.08 V (ECT is 89 °C {192 °F})

• Idle (after warm up) (MAP: 31 kPa {0.32 kgf/cm², 4.5 psi}): Approx. 1.25 V (ECT is 88 °C {190 °F})

• Racing (engine speed is 2,000 rpm) (MAP: 32 kPa {0.33 kgf/cm², 4.6 psi}): Approx. 1.31 V (ECT is 89 °C {192 °F})

• Racing (engine speed is 4,000 rpm) (MAP: 49 kPa {0.50 kgf/cm², 7.1 psi}): Approx. 2.03 V (ECT is 89 °C {192 °F})

MF_CAT1

Number of misfires in No.1 cylinder leading to catalytic converter temperature increase (catalytic converter temperature increases due to fuel combustion around catalytic converter after misfire)

—

• Displays number of misfires corresponding to possible catalytic converter damage (No.1 cylinder)

MF_CAT_2

Number of misfires in No.2 cylinder leading to catalytic converter temperature increase (catalytic converter temperature increases due to fuel combustion around catalytic converter after misfire)

—

• Displays number of misfires corresponding to possible catalytic converter damage (No.2 cylinder)

MF_CAT_3

Number of misfires in No.3 cylinder leading to catalytic converter temperature increase (catalytic converter temperature increases due to fuel combustion around catalytic converter after misfire)

—

• Displays number of misfires corresponding to possible catalytic converter damage (No.3 cylinder)

MF_CAT_4

Number of misfires in No.4 cylinder leading to catalytic converter temperature increase (catalytic converter temperature increases due to fuel combustion around catalytic converter after misfire)

—

• Displays number of misfires corresponding to possible catalytic converter damage (No.4 cylinder)

MF_EMI1

Number of misfires in No.1 cylinder under conditions required by emission regulations

—

• Displays number of misfires possibly affecting emission (No.1 cylinder)

MF_EMI_2

Number of misfires in No.2 cylinder under conditions required by emission regulations

—

• Displays number of misfires possibly affecting emission (No.2 cylinder)

MF_EMI_3

Number of misfires in No.3 cylinder under conditions required by emission regulations

—

• Displays number of misfires possibly affecting emission (No.3 cylinder)

MF_EMI_4

Number of misfires in No.4 cylinder under conditions required by emission regulations

—

• Displays number of misfires possibly affecting emission (No.4 cylinder)

RPM

Engine speed

RPM

• Displays engine speed

TP_REL

Throttle valve opening angle (relative value) with value at throttle valve fully close timing as the start point

%

• Accelerator pedal released: Approx. 12.15%

• Accelerator pedal fully depressed: Approx. 81.96%

VSS

Vehicle speed

KPH, MPH

• Displays vehicle speed

STEP

INSPECTION

RESULTS

ACTION

1

• Verify related Service Bulletins and/or on-line repair information availability.

• Is any related repair information available?

Yes

Perform repair or diagnosis according to the available repair information.

• If the vehicle is not repaired, go to the next step.

No

Go to the next step.

2

• Is the DTC P0300:00 on FREEZE FRAME DATA?

Yes

Go to the next step.

No

Go to the troubleshooting procedure for DTC on FREEZE FRAME DATA.

(See DTC TABLE [PCM (SKYACTIV-G 2.0)].)

3

NOTE:

• Recording can be facilitated using the screen capture function of the PC.

• Record the FREEZE FRAME DATA/snapshot data and DIAGNOSTIC MONITORING TEST RESULTS (misfire related) on the repair order.

—

Go to the next step.

4

• Switch the ignition off, then ON (engine off).

• Perform the Pending Trouble Code Access Procedure and DTC Reading Procedure.

  (See ON-BOARD DIAGNOSTIC TEST [PCM (SKYACTIV-G 2.0)].)

• Are any other PENDING CODEs and/or DTCs present?

Yes

Go to the applicable PENDING CODE or DTC inspection.

(See DTC TABLE [PCM (SKYACTIV-G 2.0)].)

No

Go to the next step.

5

• Start the engine.

• Access the following PIDs using the M-MDS:

  (See ON-BOARD DIAGNOSTIC TEST [PCM (SKYACTIV-G 2.0)].)

• APP1

• APP2

• ECT

• IAT

• MAF

• MAP

• MAP_V

• RPM

• TP_REL

• VSS

• Is there a PID item affected by acceleration fluctuation?

Yes

Inspect the suspected sensor and related wiring harness.

• If there is any malfunction:

• Repair or replace the malfunctioning part.

• Go to the troubleshooting procedure to perform the procedure from Step 10.

• If there is no malfunction:

• Go to the next step.

No

Go to the next step.

6

• Display the misfire rate and record the number of misfires.

• Access the following PIDs using the M-MDS

  (See ON-BOARD DIAGNOSTIC TEST [PCM (SKYACTIV-G 2.0)].)

  (See PCM INSPECTION [SKYACTIV-G 2.0].)

• MF_CAT1

• MF_CAT_2

• MF_CAT_3

• MF_CAT_4

• MF_EMI1

• MF_EMI_2

• MF_EMI_3

• MF_EMI_4

—

Go to the next step.

7

• Switch the spark plugs on a cylinder that is misfiring and a cylinder that is not misfiring.

  (See SPARK PLUG REMOVAL/INSTALLATION [SKYACTIV-G 2.0].)

• Start the engine.

• Verify all accessory loads (A/C, headlights, blower fan, rear window defogger) are off.

• Under no-load conditions (P or N position (AT)/neutral (MT)), increase the engine speed to 3,000 rpm.

• Display the misfire rate and record the number of misfires.

• Access the following PIDs using the M-MDS

  (See ON-BOARD DIAGNOSTIC TEST [PCM (SKYACTIV-G 2.0)].)

  (See PCM INSPECTION [SKYACTIV-G 2.0].)

• MF_CAT1

• MF_CAT_2

• MF_CAT_3

• MF_CAT_4

• MF_EMI1

• MF_EMI_2

• MF_EMI_3

• MF_EMI_4

• Is there a change from the recorded number of misfires?

Yes

Go to the troubleshooting procedure to perform the procedure from Step 1.

No

Go to the next step.

8

• Switch the ignition coils on a cylinder that is misfiring and a cylinder that is not misfiring.

  (See IGNITION COIL/ION SENSOR REMOVAL/INSTALLATION [SKYACTIV-G 2.0].)

• Start the engine.

• Verify all accessory loads (A/C, headlights, blower fan, rear window defogger) are off.

• Under no-load conditions (P or N position (AT)/neutral (MT)), increase the engine speed to 3,000 rpm.

• Display the misfire rate and record the number of misfires.

• Access the following PIDs using the M-MDS

  (See ON-BOARD DIAGNOSTIC TEST [PCM (SKYACTIV-G 2.0)].)

  (See PCM INSPECTION [SKYACTIV-G 2.0].)

• MF_CAT1

• MF_CAT_2

• MF_CAT_3

• MF_CAT_4

• MF_EMI1

• MF_EMI_2

• MF_EMI_3

• MF_EMI_4

• Is there a change from the recorded number of misfires?

Yes

Go to the troubleshooting procedure to perform the procedure from Step 2.

No

Go to the troubleshooting procedure to perform the procedure from Step 3.

STEP

INSPECTION

RESULTS

ACTION

1

• Inspect the spark plug.

  (See SPARK PLUG INSPECTION [SKYACTIV-G 2.0].)

• Is there any malfunction?

Yes

Replace the spark plug, then go to Step 10.

(See SPARK PLUG REMOVAL/INSTALLATION [SKYACTIV-G 2.0].)

No

Go to the next step.

2

• Inspect the ignition coil.

  (See IGNITION COIL INSPECTION [SKYACTIV-G 2.0].)

• Is there any malfunction?

Yes

Replace the ignition coil/ion sensor, then go to Step 10.

(See IGNITION COIL/ION SENSOR REMOVAL/INSTALLATION [SKYACTIV-G 2.0].)

No

Go to the next step.

3

• Inspect the fuel injector.

  (See FUEL INJECTOR INSPECTION [SKYACTIV-G 2.0].)

• Is there any malfunction?

Yes

Replace the fuel injector, then go to Step 10.

(See FUEL INJECTOR REMOVAL/INSTALLATION [SKYACTIV-G 2.0].)

No

Go to the next step.

4

• Visually inspect for loose, cracked or damaged hoses on intake air system.

• Is there any malfunction?

Yes

Repair or replace the malfunctioning part according to the inspection results, then go to Step 10.

No

Go to the next step.

5

• Verify the condition of the drive belt assembly.

  (See DRIVE BELT INSPECTION [SKYACTIV-G 2.0].)

• Is there any malfunction?

Yes

Assemble drive belt correctly, then go to Step 10.

(See DRIVE BELT REMOVAL/INSTALLATION [SKYACTIV-G 2.0].)

No

Go to the next step.

6

• Verify if oil is on the drive belt.

• Is there foreign matter on the drive belt?

Yes

Remove the foreign matter on the drive belt, then go to Step 10.

No

Go to the next step.

7

• Inspect the drive belt auto tensioner.

  (See DRIVE BELT AUTO TENSIONER INSPECTION [SKYACTIV-G 2.0].)

• Is there any malfunction?

Yes

Replace the drive belt auto tensioner, then go to Step 10.

(See DRIVE BELT AUTO TENSIONER REMOVAL/INSTALLATION [SKYACTIV-G 2.0].)

No

Go to the next step.

8

• Inspect the engine compression.

  (See COMPRESSION INSPECTION [SKYACTIV-G 2.0].)

• Are compression pressures within specification?

Yes

Go to the next step.

No

Replace or overhaul the engine, then go to Step 10.

9

• Perform the “ENGINE COOLANT LEAKAGE INSPECTION”.

  (See ENGINE COOLANT LEAKAGE INSPECTION [SKYACTIV-G 2.0].)

• Does the radiator cap tester needle drop even though there is no engine coolant leakage from the radiator or the hoses?

Yes

Engine coolant leakage from the engine (between the combustion chamber and the engine coolant passage) may have occurred.

• Verify the conditions of the gasket and the cylinder head.

• If there is any malfunction:

• Repair or replace the malfunctioning part according to the inspection results, then go to the next step.

No

Go to the next step.

10

• Always reconnect all disconnected connectors.

• Clear the DTC from the PCM memory using the M-MDS.

  (See CLEARING DTC [PCM (SKYACTIV-G 2.0)].)

• Implement the repeatability verification procedure.

  (See Repeatability Verification Procedure.)

• Perform the Pending Trouble Code Access Procedure.

  (See ON-BOARD DIAGNOSTIC TEST [PCM (SKYACTIV-G 2.0)].)

• Is the PENDING CODE for this DTC present?

Yes

Repeat the inspection from Step 1.

• If the malfunction recurs, replace the PCM.

  (See PCM REMOVAL/INSTALLATION [SKYACTIV-G 2.0].)

Go to the next step.

No

Go to the next step.

11

• Is any other DTC or pending code stored?

Yes

Go to the applicable DTC inspection.

(See DTC TABLE [PCM (SKYACTIV-G 2.0)].)

No

DTC troubleshooting completed.