28

SPARK PLUG CONDITION

DESCRIPTION

• Incorrect spark plug condition.

POSSIBLE CAUSE

NOTE:

• Inspecting the spark plug conditions can determine whether a problem is related to a specific cylinder or possibly all cylinders.

Wet/carbon stuck on specific plug:

• Spark—Weak, not visible

• Air/fuel mixture—Excessive fuel injection volume

• Compression—No compression, low compression

• Malfunction spark plug

Grayish white with specific plug:

• Air/fuel mixture—Insufficient fuel injection volume

• Malfunction spark plug

Wet/carbon is stuck on all plugs:

• Spark—Spark weak

• Air/fuel mixture—Too rich, excessive fuel line pressure

• Erratic signal to PCM

• ECT sensor No.1 or related circuit malfunction

• MAF sensor or related circuit malfunction

• A/F sensor or related circuit malfunction

• HO2S or related circuit malfunction

• Compression—Low compression

• Restriction in intake/exhaust system

Grayish white with all plugs:

• Erratic signal to PCM

• ECT sensor No.1 or related circuit malfunction

• MAF sensor or related circuit malfunction

• A/F sensor or related circuit malfunction

• HO2S or related circuit malfunction

• Air/fuel mixture—Too lean, insufficient fuel line pressure

WARNING:

• The following troubleshooting flow chart contains the fuel system diagnosis and repair procedures. Read the following warnings before servicing the fuel system:

• Fuel vapor is hazardous. It can easily ignite, causing serious injury and damage. Always keep sparks and flames away from fuel.

• Fuel line spills and leakage are dangerous. Fuel can ignite and cause serious injuries or death and damage. Fuel can also irritate skin and eyes. To prevent this, always complete “BEFORE SERVICE PRECAUTION” and “AFTER SERVICE PRECAUTION” described in this manual. (See BEFORE SERVICE PRECAUTION [SKYACTIV-G 2.5].) (See AFTER SERVICE PRECAUTION [SKYACTIV-G 2.5].)

CAUTION:

• Disconnecting/connecting the quick release connector without cleaning it may cause damage to the fuel pipe and the quick release connector. Always clean the quick release connector joint area before disconnecting/connecting, and make sure that it is free of foreign matter.

Item (definition)

Unit/Condition

Definition

Condition/Specification (Reference)

ECT

°C, °F

Engine coolant temperature (No.1)

• Displays ECT

V

• ECT is 20 °C {68 °F}: Approx. 3.10 V

• ECT is 40 °C {104 °F}: Approx. 2.16 V

• ECT is 60 °C {140 °F}: Approx. 1.40 V

• ECT is 80 °C {176 °F}: Approx. 0.87 V

• ECT is 100 °C {212 °F}: Approx. 0.54 V

MAF

g/Sec

Mass air flow

• Displays MAF

V

• Switch ignition ON (engine off) (MAF: 0.59 g/s {0.078 lb/min}): Approx. 0.72 V

• Idle (after warm up) (MAF: 2.17 g/s {0.287 lb/min}): Approx. 0.86 V

• Racing (engine speed is 2,000 rpm) (MAF: 4.73 g/s {0.626 lb/min}): Approx. 1.07 V

O2S11

µA

A/F sensor

• Idle (after warm up): Approx. -39 µA

• Deceleration fuel cut (accelerator pedal released from engine speed of 4,000 rpm or more): Approx. 3.84 mA

O2S12

V

HO2S

• Idle (after warm up): 0—1.0 V

• Deceleration fuel cut (accelerator pedal released from engine speed of 4,000 rpm or more): Approx. 0 V

RPM

RPM

Engine speed

• Displays engine speed

VSS

KPH, MPH

Vehicle speed

• Displays vehicle speed

STEP

INSPECTION

RESULTS

ACTION

1

• Remove all spark plugs.

  (See SPARK PLUG REMOVAL/INSTALLATION [SKYACTIV-G 2.5].)

• Inspect the spark plug.

  (See SPARK PLUG INSPECTION [SKYACTIV-G 2.5].)

• Is there any malfunction?

Yes

Specific plug is wet or covered with carbon:

• Go to the next step.

Specific plug looks grayish white:

• Go to Step 7.

All plugs are wet or covered with carbon:

• Go to Step 9.

All plugs look grayish white:

• Go to Step 15.

No

Symptom troubleshooting completed.

2

• Are the spark plugs wet/covered with carbon from the engine oil?

Yes

Inspect all areas related to oil, working up and down.

Repair or replace the malfunctioning part according to the inspection results.

No

Go to the next step.

3

• Inspect the spark plugs for the following:

• Air gap

• Cracked insulator

• Heat range

• Worn electrode

• Is there any malfunction?

Yes

Replace the spark plug.

(See SPARK PLUG REMOVAL/INSTALLATION [SKYACTIV-G 2.5].)

No

Go to the next step.

4

• Inspect the compression pressure at the suspected cylinder.

  (See COMPRESSION INSPECTION [SKYACTIV-G 2.5].)

• Are compression pressures within specification?

Specification:

• Compression

• Standard: 954 kPa {9.73 kgf/cm², 138 psi} (300 rpm)

• Minimum: 763 kPa {7.78 kgf/cm², 111 psi} (300 rpm)

• Maximum difference between cylinders: 161 kPa {1.64 kgf/cm², 23.4 psi} (300 rpm)

NOTE:

• Because the SKYACTIV-G 2.5 retards the intake valve closing timing, compression pressure is low.

Yes

Go to the next step.

No

Repair or replace the malfunctioning part according to the inspection results.

5

• Reinstall all spark plugs.

  (See SPARK PLUG REMOVAL/INSTALLATION [SKYACTIV-G 2.5].)

• Perform the Spark Test at the suspected cylinder.

  (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [SKYACTIV-G 2.5].)

• Is a strong blue spark visible (compare with normal cylinder)?

Yes

Go to the next step.

No

Repair or replace the malfunctioning part according to the inspection results.

6

• Inspect the fuel line pressure.

  (See FUEL LINE PRESSURE INSPECTION [SKYACTIV-G 2.5].)

• Is the low side fuel pressure within specification?

Specification:

• 405—485 kPa {4.13—4.94 kgf/cm², 58.8—70.3 psi}

Yes

Inspect the fuel injector for the following:

• Injection volume

• Leakage

• Open or short circuit in injector

Repair or replace the malfunctioning part according to the inspection results.

No

Zero or low:

• Inspect the fuel pump relay and the fuel pump circuit.

  (See RELAY INSPECTION.)

• Inspect the fuel line for restriction.

• If there is any malfunction:

• Repair or replace the malfunctioning part according to the inspection results.

• If there is no malfunction:

• Replace the fuel pump unit. (Pressure regulator or fuel pump malfunction)

  (See FUEL PUMP UNIT REMOVAL/INSTALLATION [SKYACTIV-G 2.5].)

High:

• Replace the fuel pump unit. (Pressure regulator malfunction)

  (See FUEL PUMP UNIT REMOVAL/INSTALLATION [SKYACTIV-G 2.5].)

7

• Inspect the spark plug for the following:

• Air gap

• Heat range

• Is there any malfunction?

Yes

Replace the spark plug.

(See SPARK PLUG REMOVAL/INSTALLATION [SKYACTIV-G 2.5].)

No

Go to the next step.

8

• Perform the Fuel Injector Operation Inspection.

  (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [SKYACTIV-G 2.5].)

• Do the fuel injectors operate properly?

Yes

Go to the next step.

No

Repair or replace the malfunctioning part according to the inspection results.

9

• Is the air cleaner element clean?

Yes

Go to the next step.

No

Replace the air cleaner element.

10

• Access the following PIDs using the M-MDS:

  (See ON-BOARD DIAGNOSTIC TEST [SKYACTIV-G 2.5].)

• ECT

• MAF

• O2S11 (When engine can be started)

• O2S12 (When engine can be started)

• Are the PIDs normal?

  (See PCM INSPECTION [SKYACTIV-G 2.5].)

Yes

Go to the next step.

No

ECT PID is not as specified:

• Inspect for an intermittent open circuit of the ECT sensor No.1 and the related wiring harness.

  (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR INSPECTION [SKYACTIV-G 2.5].)

MAF PID is not as specified:

• Inspect for an intermittent open circuit of the MAF sensor and the related wiring harness.

  (See MASS AIR FLOW (MAF) SENSOR INSPECTION [SKYACTIV-G 2.5].)

O2S11 PID is not as specified:

• Inspect for an intermittent open circuit of the A/F sensor and the related wiring harness.

  (See AIR FUEL RATIO (A/F) SENSOR INSPECTION [SKYACTIV-G 2.5].)

O2S12 PID is not as specified:

• Inspect for an intermittent open circuit of the HO2S and the related wiring harness.

  (See HEATED OXYGEN SENSOR (HO2S) INSPECTION [SKYACTIV-G 2.5].)

Repair or replace the malfunctioning part according to the inspection results.

11

• Perform the Purge Control System Inspection when the engine can be started.

  (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [SKYACTIV-G 2.5].)

• Is there any malfunction?

Yes

Repair or replace the malfunctioning part according to the inspection results.

No

Go to the next step.

12

• Perform the Spark Test.

  (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [SKYACTIV-G 2.5].)

• Is a strong blue spark visible at each cylinder?

Yes

Go to the next step.

No

Repair or replace the malfunctioning part according to the inspection results.

13

• Measure the compression pressure for each cylinder.

  (See COMPRESSION INSPECTION [SKYACTIV-G 2.5].)

• Are compression pressures within specification?

Specification:

• Compression

• Standard: 954 kPa {9.73 kgf/cm², 138 psi} (300 rpm)

• Minimum: 763 kPa {7.78 kgf/cm², 111 psi} (300 rpm)

• Maximum difference between cylinders: 161 kPa {1.64 kgf/cm², 23.4 psi} (300 rpm)

NOTE:

• Because the SKYACTIV-G 2.5 retards the intake valve closing timing, compression pressure is low.

Yes

Go to the next step.

No

Repair or replace the malfunctioning part according to the inspection results.

14

• Inspect the fuel line pressure.

  (See FUEL LINE PRESSURE INSPECTION [SKYACTIV-G 2.5].)

• Is the low side fuel pressure within specification?

Specification:

• 405—485 kPa {4.13—4.94 kgf/cm², 58.8—70.3 psi}

Yes

Visually inspect for deformed exhaust system parts.

Repair or replace the malfunctioning part according to the inspection results.

No

Zero or low:

• Inspect the fuel pump relay and the fuel pump circuit.

  (See RELAY INSPECTION.)

• Inspect the fuel line for restriction.

• If there is any malfunction:

• Repair or replace the malfunctioning part according to the inspection results.

• If there is no malfunction:

• Replace the fuel pump unit. (Pressure regulator or fuel pump malfunction)

  (See FUEL PUMP UNIT REMOVAL/INSTALLATION [SKYACTIV-G 2.5].)

High:

• Replace the fuel pump unit. (Pressure regulator malfunction)

  (See FUEL PUMP UNIT REMOVAL/INSTALLATION [SKYACTIV-G 2.5].)

15

• Access the following PIDs using the M-MDS:

  (See ON-BOARD DIAGNOSTIC TEST [SKYACTIV-G 2.5].)

• ECT

• MAF

• O2S11 (When engine can be started)

• O2S12 (When engine can be started)

• Are the PIDs normal?

  (See PCM INSPECTION [SKYACTIV-G 2.5].)

Yes

Go to the next step.

No

ECT PID is not as specified:

• Inspect for an intermittent open circuit of the ECT sensor No.1 and the related wiring harness.

  (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR INSPECTION [SKYACTIV-G 2.5].)

MAF PID is not as specified:

• Inspect for an intermittent open circuit of the MAF sensor and the related wiring harness.

  (See MASS AIR FLOW (MAF) SENSOR INSPECTION [SKYACTIV-G 2.5].)

O2S11 PID is not as specified:

• Inspect for an intermittent open circuit of the A/F sensor and the related wiring harness.

  (See AIR FUEL RATIO (A/F) SENSOR INSPECTION [SKYACTIV-G 2.5].)

O2S12 PID is not as specified:

• Inspect for an intermittent open circuit of the HO2S and the related wiring harness.

  (See HEATED OXYGEN SENSOR (HO2S) INSPECTION [SKYACTIV-G 2.5].)

Repair or replace the malfunctioning part according to the inspection results.

16

• If the engine cannot be started:

• Inspect the intake air system for air leakage.

• If the engine can be started:

• Perform the Intake Manifold Vacuum Inspection.

  (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [SKYACTIV-G 2.5].)

• Is air being sucked in from intake air system?

Yes

Repair or replace the malfunctioning part according to the inspection results.

No

Go to the next step.

17

• Inspect the fuel line pressure.

  (See FUEL LINE PRESSURE INSPECTION [SKYACTIV-G 2.5].)

• Is the low side fuel pressure within specification?

Specification:

• 405—485 kPa {4.13—4.94 kgf/cm², 58.8—70.3 psi}

Yes

Inspect the PCM ground condition.

Repair or replace the malfunctioning part according to the inspection results.

No

Zero or low:

• Inspect the fuel pump relay and the fuel pump circuit.

  (See RELAY INSPECTION.)

• Inspect the fuel line for restriction.

• If there is any malfunction:

• Repair or replace the malfunctioning part according to the inspection results.

• If there is no malfunction:

• Replace the fuel pump unit. (Pressure regulator or fuel pump malfunction)

  (See FUEL PUMP UNIT REMOVAL/INSTALLATION [SKYACTIV-G 2.5].)

High:

• Replace the fuel pump unit. (Pressure regulator malfunction)

  (See FUEL PUMP UNIT REMOVAL/INSTALLATION [SKYACTIV-G 2.5].)

18

Verify the test results.

• If normal, return to the diagnostic index to service any additional symptoms.

  (See SYMPTOM DIAGNOSTIC INDEX [SKYACTIV-G 2.5].)

• If the malfunction remains, inspect the related Service Bulletins and/or On-line Repair Information and perform repair or diagnosis.

• If the vehicle is repaired, troubleshooting is completed.

• If the vehicle is not repaired or additional diagnostic information is not available, reprogram the PCM if a later calibration is available. Retest.