DTC P0301, P0302, P0303, P0304 [L8, LF]

id0102b1806600

DTC P0301 | Cylinder No.1 misfire detected
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DTC P0302 | Cylinder No.2 misfire detected
DTC P0303 | Cylinder No.3 misfire detected
DTC P0304 | Cylinder No.4 misfire detected
DETECTION CONDITION | • The PCM monitors the CKP sensor input signal interval time. The PCM calculates the change of interval time for each cylinder. If the change of interval time exceeds the preprogrammed criteria, the PCM detects a misfire in the corresponding cylinder. While the engine is running, the PCM counts number of misfires that occurred at 200 crankshaft revolutions and 1,000 crankshaft revolutions and calculates misfire ratio for each crankshaft revolution. If the ratio exceeds the preprogrammed criteria, the PCM determines that a misfire, which can damage catalytic converter or affect emission performance, has occurred. Diagnostic support note • This is a continuous monitor (Misfire). • The MIL illuminates if the PCM detects the misfire which affects emission performance in two consecutive drive cycles or in one drive cycle while the DTC for the same malfunction has been stored in the PCM. • The MIL flashes if the PCM detects the misfire which can damage the catalytic converter during the first drive cycle. • PENDING CODE is available if the PCM detects the misfire which affects emission performance during the first drive cycle. • FREEZE FRAME DATA (Mode 2/Mode 12) is available. • The DTC is stored in the PCM memory.
POSSIBLE CAUSE | • Erratic signal to PCM ― APP sensor signal malfunction ― ECT sensor signal malfunction ― IAT sensor signal malfunction ― MAF sensor signal malfunction ― CKP sensor signal malfunction ― TP sensor signal malfunction ― VSS signal malfunction • Ignition system malfunction ― Ignition coil related wiring harness malfunction ― Ignition coil malfunction ― Spark plug malfunction • Air suction in intake air system (between dynamic chamber and cylinder head) • Fuel injector related wiring harness malfunction • Engine malfunction ― Engine coolant leakage ― Insufficient compression • Improper operation of fuel injector • PCM malfunction

Diagnostic procedure

STEP | INSPECTION | ACTION
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1 | VERIFY FREEZE FRAME DATA (MODE 12) AND DIAGNOSTIC MONITORING TEST RESULTS HAVE BEEN RECORDED • Have the FREEZE FRAME DATA (Mode 12) and DIAGNOSTIC MONITORING TEST RESULTS (misfire related) been recorded? | Yes | Go to the next step.
No | Record the FREEZE FRAME DATA (Mode 12) and DIAGNOSTIC MONITORING TEST RESULTS on repair order, then go to the next step.
2 | VERIFY RELATED SERVICE INFORMATION AVAILABILITY • Verify related Service Information availability. • Is any related Service Information available? | Yes | Perform repair or diagnosis according to the available Service Information. • If the vehicle is not repaired, go to the next step.
No | Go to the next step.
3 | VERIFY RELATED PENDING CODE AND STORED DTC • Turn the ignition switch off then to the ON position (engine off). • Perform the Pending Trouble Code Access Procedure and DTC Reading Procedure. (See ON-BOARD DIAGNOSTIC TEST [L8, LF].) • Are any DTCs present? | Yes | Go to the applicable DTC troubleshooting. (See DTC TABLE [L8, LF].)
No | Go to the next step.
4 | VERIFY CURRENT INPUT SIGNAL STATUS • Perform the PID/DATA Monitor and Record Procedure and access the following PIDs. (See ON-BOARD DIAGNOSTIC TEST [L8, LF].) ― APP1 ― APP2 ― ECT ― IAT ― MAF ― RPM ― TP REL ― VSS • Is there any signal that is far out of specification when the ignition switch is turned to the ON position and the engine idles? (See PCM INSPECTION [L8, LF].) | Yes | Repair or replace the malfunctioning part according to the inspection results, then go to Step 14.
No | Go to the next step.
5 | VERIFY CURRENT INPUT SIGNAL STATUS UNDER FREEZE FRAME DATA (MODE 2) CONDITION • Perform the PID/DATA Monitor and Record Procedure and access the same PIDs as in Step 4 under the FREEZE FRAME DATA (Mode 2) condition. (See ON-BOARD DIAGNOSTIC TEST [L8, LF].) • Is there any signal which causes drastic changes? | Yes | Repair or replace the malfunctioning part according to the inspection results, then go to Step 14.
No | Go to the next step.
6 | INSPECT SPARK PLUG CONDITION • Turn the ignition switch off. • Remove the spark plug from suspected cylinder. (See SPARK PLUG REMOVAL/INSTALLATION [L8, LF].) • Inspect the spark plug for the following condition: ― Cracks ― Excess wear ― Gap ― Wet • Is there any malfunction? | Yes | If the spark plug is wet: • Fuel flooding is suspected. If the spark plug has a cracks excessive wear or improper gap: • Replace the suspected spark plug. (See SPARK PLUG REMOVAL/INSTALLATION [L8, LF].) Go to Step 14.
No | Go to the next step.
7 | INSPECT IGNITION COIL AND RELATED WIRING HARNESS • Inspect the ignition coil and related wiring harness condition (intermittent open or short) for all cylinders. • Is there any malfunction? | Yes | Repair or replace the malfunctioning part according to the inspection results, then go to Step 14.
No | Go to the next step.
8 | INSPECT IGNITION SYSTEM OPERATION • Perform the Spark Test. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [L8, LF].) • Is 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, then go to Step 14.
9 | INSPECT AIR SUCTION IN INTAKE AIR SYSTEM • Inspect for air leakage at the following: ― Around connection of dynamic chamber and intake manifold ― Around connection of intake manifold and cylinder head Note • Engine speed may change when rust penetrating agent is stayed on the air suction area. • Is there air leakage? | Yes | Repair or replace the malfunctioning part according to the inspection results, then go to Step 14.
No | Go to the next step.
10 | INSPECT FUEL INJECTOR RELATED WIRING HARNESS • Remove the intake air system parts. (See INTAKE-AIR SYSTEM REMOVAL/INSTALLATION [L8, LF].) • Disconnect the fuel injector connector on suspected cylinder. • Connect the NOID LIGHT to fuel injector terminals. • Inspect the dim of light during cranking. • Does the light illuminate? | Yes | Go to the next step.
No | Inspect the fuel injector related wiring harness. Repair or replace the suspected wiring harness, if necessary. Go to Step 14.
11 | INSPECT SEALING OF ENGINE COOLANT PASSAGE • Perform the “ENGINE COOLANT LEAKAGE INSPECTION.” (See ENGINE COOLANT LEAKAGE INSPECTION [L8, LF].) • Is there any malfunction? | Yes | Repair or replace the malfunctioning part according to the inspection results, then go to Step 14.
No | Go to the next step.
12 | INSPECT ENGINE COMPRESSION • Inspect the engine compression. (See COMPRESSION INSPECTION [L8, LF].) • Is there any malfunction? | Yes | Perform the engine overhaul for repairs, then go to Step 14.
No | Go to the next step.
13 | INSPECT FUEL INJECTOR OPERATION • Remove the fuel injector from suspected cylinder. (See FUEL INJECTOR REMOVAL/INSTALLATION [L8, LF].) • Switch the fuel injector with the fuel injector on other cylinder. • Start the engine and idle it. • Is the misfire DTC for cylinder which has a suspected fuel injector? | Yes | Replace the injector, then go to the next step. (See FUEL INJECTOR REMOVAL/INSTALLATION [L8, LF].)
No | Go to the next step.
14 | VERIFY DTC TROUBLESHOOTING COMPLETED • Make sure to reconnect all disconnected connectors. • Start the engine. • Clear the DTC from the PCM memory using the M-MDS. (See AFTER REPAIR PROCEDURE [L8, LF].) • Perform the KOER self test. (See KOEO/KOER SELF TEST [L8, LF].) • Is the PENDING CODE for this DTC present? | Yes | Replace the PCM, then go to the next step. (See PCM REMOVAL/INSTALLATION [L8, LF].)
No | Go to the next step.
15 | VERIFY AFTER REPAIR PROCEDURE • Perform the “AFTER REPAIR PROCEDURE”. (See AFTER REPAIR PROCEDURE [L8, LF].) • Are any DTCs present? | Yes | Go to the applicable DTC troubleshooting. (See DTC TABLE [L8, LF].)
No | DTC troubleshooting completed.