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DTC P0304 CYLINDER 4 MISFIRE DETECTED

DTC P0304 CYLINDER 4 MISFIRE DETECTED

DTC DETECTING CONDITION:


• Two consecutive driving cycles with fault

• Immediately at fault recognition (A misfire which could damage catalyst occurs.)

• GENERAL DESCRIPTION


TROUBLE SYMPTOM:


• Engine stalls.

• Erroneous idling

• Rough driving


Important

After repair or replacement of faulty parts, conduct Clear Memory Mode and Inspection Mode .


WIRING DIAGRAM:


CHECK ANY OTHER DTC ON DISPLAY.

Is any other DTC displayed?

Yes

Inspect the relevant DTC using “List of Diagnostic Trouble Code (DTC)”.


No


CHECK OUTPUT SIGNAL FROM ECM.

Turn the ignition switch to ON.

Measure the voltage between ECM connector and chassis ground on faulty cylinders.

Connector & terminal

#1 (B84) No. 1 (+) — Chassis ground (−):

#2 (B137) No. 6 (+) — Chassis ground (−):

#3 (B137) No. 5 (+) — Chassis ground (−):

#4 (B137) No. 4 (+) — Chassis ground (−):

Is the voltage more than 10 V?

Yes


No


CHECK HARNESS BETWEEN FUEL INJECTOR AND ECM CONNECTOR.

Turn the ignition switch to OFF.

Disconnect the connector from fuel injector on faulty cylinders.

Disconnect the connector from ECM.

Measure the resistance between ECM connector and engine ground on faulty cylinders.

Connector & terminal

#1 (E5) No. 1 — Engine ground:

#2 (E16) No. 1 — Engine ground:

#3 (E6) No. 1 — Engine ground:

#4 (E17) No. 1 — Engine ground:

Is the resistance more than 1 MΩ?

Yes


No

Repair the ground short circuit in harness between fuel injector and ECM connector.


CHECK HARNESS BETWEEN FUEL INJECTOR AND ECM CONNECTOR.

Measure the resistance of harness connector between ECM connector and fuel injector on faulty cylinders.

Connector & terminal

#1 (B84) No. 1 — (E5) No. 1:

#2 (B137) No. 6 — (E16) No. 1:

#3 (B137) No. 5 — (E6) No. 1:

#4 (B137) No. 4 — (E17) No. 1:

Is the resistance less than 1 Ω?

Yes


No

• Repair the harness and connector.

•
Note

In this case, repair the following:

• Open circuit in harness between ECM and fuel injector connector

• Poor contact in coupling connector



CHECK FUEL INJECTOR.

Measure the resistance between fuel injector terminals on faulty cylinder.

Terminals

No. 1 — No. 2:

Is the resistance 5 — 20 Ω?

Yes


No

Replace the faulty fuel injector.


CHECK POWER SUPPLY LINE.

Turn the ignition switch to ON.

Measure the voltage between fuel injector and engine ground on faulty cylinders.

Connector & terminal

#1 (E5) No. 2 (+) — Engine ground (−):

#2 (E16) No. 2 (+) — Engine ground (−):

#3 (E6) No. 2 (+) — Engine ground (−):

#4 (E17) No. 2 (+) — Engine ground (−):

Is the voltage more than 10 V?

Yes

Repair the poor contact in all connectors in fuel injector circuit.


No

• Repair the harness and connector.

•
Note

In this case, repair the following:

• Open circuit in harness between main relay and fuel injector connector on faulty cylinders

• Poor contact in coupling connector

• Poor contact in main relay connector

• Poor contact in fuel injector connector on faulty cylinders



CHECK HARNESS BETWEEN FUEL INJECTOR AND ECM CONNECTOR.

Turn the ignition switch to OFF.

Disconnect the connector from fuel injector on faulty cylinder.

Turn the ignition switch to ON.

Measure the voltage between ECM connector and chassis ground on faulty cylinders.

Connector & terminal

#1 (B84) No. 1 (+) — Chassis ground (−):

#2 (B137) No. 6 (+) — Chassis ground (−):

#3 (B137) No. 5 (+) — Chassis ground (−):

#4 (B137) No. 4 (+) — Chassis ground (−):

Is the voltage more than 10 V?

Yes

Repair the battery short circuit in harness between ECM and fuel injector. After repair, replace the ECM.


No


CHECK FUEL INJECTOR.

Turn the ignition switch to OFF.

Measure the resistance between fuel injector terminals on faulty cylinder.

Terminals

No. 1 — No. 2:

Is the resistance less than 1 Ω?

Yes

Replace the faulty fuel injector and ECM


No


CHECK INSTALLATION OF CAMSHAFT POSITION SENSOR/CRANKSHAFT POSITION SENSOR.

Is the camshaft position sensor or crankshaft position sensor loosely installed?

Yes

Tighten the camshaft position sensor or crankshaft position sensor.


No


CHECK CRANK SPROCKET.

Remove the timing belt cover.

Is the crank sprocket rusted or does it have broken teeth?

Yes

Replace the crank sprocket.


No


CHECK INSTALLATION CONDITION OF TIMING BELT.

Turn the crankshaft, and align alignment mark on crank sprocket with alignment mark on cylinder block.

Is the timing belt dislocated from its proper position?

Yes

Repair the installation condition of timing belt.


No


CHECK FUEL LEVEL.

Is the fuel meter indication higher than the “Lower” level?

Yes


No

Replenish the fuel so fuel meter indication is higher than the “Lower” level. After replenishing fuel;


CHECK STATUS OF MALFUNCTION INDICATOR LIGHT.

Clear the memory using Vehicle Diagnostic Interface.



Start the engine, and drive the vehicle more than 10 minutes.

Is the malfunction indicator light coming on or blinking?

Yes


No


CHECK CAUSE OF MISFIRE DIAGNOSED.

Was the cause of misfire diagnosed when the engine is running?

Yes

Finish the diagnostics operation, if the engine has no abnormality.


No

• Repair the poor contact.

•
Note

In this case, repair the following:

• Poor contact in ignition coil connector

• Poor contact in fuel injector connector on faulty cylinders

• Poor contact in ECM connector

• Poor contact in coupling connector



CHECK AIR INTAKE SYSTEM.

Is there a fault in air intake system?

Yes

• Repair the air intake system.

•
Note

Check the following items:

• Are there air leaks or air suction caused by loose or dislocated nuts and bolts?

• Are there cracks or any disconnection of hoses?



No


CHECK CYLINDER.

Is there a fault in that cylinder?

Yes

• Repair or replace the faulty parts.

•
Note

Check the following items.

• Spark plug

• Fuel injector

• Compression pressure



No

Go to DTC P0171 and P0172.