DTC P0300 [L8, LF]

id0102b1806500

DTC P0300

Random misfire detected
DETECTION CONDITION
•  The PCM monitors the CKP sensor input signal interval time. The PCM calculates change of interval time for each cylinder. If change of interval time exceeds preprogrammed criteria, the PCM detects 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
•  CMP sensor malfunction
•  CKP sensor looseness
•  Ignition system malfunction
―  Ignition coil related wiring harness malfunction
―  Ignition coil malfunction
―  Spark plug malfunction
•  MAF sensor contamination
•  Excess air suction in intake air system (between MAF sensor and intake manifold)
―  Vacuum hose damaged
―  Pipe malfunction
•  Fuel supply system malfunction or improper fuel line pressure
―  Fuel pressure regulator (built-in fuel pump unit) malfunction
―  Fuel leakage in fuel line
―  Fuel line clogged
―  Fuel filter clogged
―  Fuel pump unit malfunction
―  Fuel runout
•  Insufficient compression
•  Improper operation of variable valve timing control system
•  Improper operation of purge solenoid valve
•  Improper operation of EGR valve
•  Engine coolant leakage
•  Improper operation of PCV valve
•  Poor quality fuel
•  PCM malfunction

Diagnostic procedure

STEP

INSPECTION

ACTION
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.
•  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.
―  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?
Yes
Repair or replace the malfunctioning part according to the inspection results, then go to Step 20.
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.
•  Is there any signal which causes drastic changes?
Yes
Repair or replace the malfunctioning part according to the inspection results, then go to Step 20.
No
Go to the next step.
6
INSPECT CMP SENSOR
•  Inspect the CMP sensor.
•  Is there any malfunction?
Yes
Inspect the installation condition and damages on timing chain and gears.
If there is a malfunction:
•  Repair or replace the malfunctioning part according to the inspection results.
If it is normal:
•  Replace the CMP sensor.
Go to Step 20.
No
Go to the next step.
7
INSPECT INSTALLATION OF CKP SENSOR
•  Inspect if the CKP sensor is loosely installed.
•  Is the sensor installed securely?
Yes
Go to the next step.
No
Retighten the CKP sensor, then go to Step 20.
8
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 20.
No
Go to the next step.
9
INSPECT IGNITION SYSTEM OPERATION
•  Perform the Spark Test.
•  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 20.
10
INSPECT MAF PID
•  Start the engine.
•  Perform the PID/DATA Monitor and Record Procedure and access the MAF PID.
•  Race the engine and verify that the MAF PID changes quickly according to change in the engine speed.
•  Is the MAF PID response normal?
Yes
Go to Step 12.
No
Go to the next step.
11
INSPECT EXCESSIVE AIR SUCTION IN INTAKE AIR SYSTEM
•  Inspect for air leakage between the following:
―  MAF sensor and throttle body
―  Throttle body and intake manifold
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 20.
No
Replace the MAF sensor, then go to Step 20.
(See INTAKE-AIR SYSTEM REMOVAL/INSTALLATION [L8, LF].)
12
INSPECT FUEL LINE PRESSURE
•  Inspect the fuel line pressure.
•  Is the fuel line pressure normal?
Yes
Go to Step 14.
No
If the fuel line pressure is too low:
•  Go to the next step.
If the fuel line pressure is excess high:
•  Replace the fuel pump unit, then go to Step 20.
13
INSPECT FUEL LINE FROM FUEL PUMP TO FUEL DISTRIBUTOR
•  Visually inspect the fuel line for fuel leakage.
•  Is there fuel leakage?
Yes
Repair or replace the malfunctioning part according to the inspection results, then go to Step 20.
No
Inspect fuel filters for the foreign materials or stain inside fuel filter (low-pressure side).
Perform the following actions according to the inspection results:
•  If the foreign materials or stain is found inside fuel filter (low-pressure side):
―  Clean the fuel tank and filter (low-pressure side).
•  If normal:
―  Replace the fuel pump unit.
Go to Step 20.
14
INSPECT ENGINE COMPRESSION
•  Inspect the engine compression.
•  Is there any malfunction?
Yes
Perform the engine overhaul for repairs, then go to Step 20.
No
Go to the next step.
15
INSPECT VARIABLE VALVE TIMING CONTROL SYSTEM OPERATION
•  Perform the Variable Valve Timing Control System Operation Inspection.
•  Does the variable valve timing control system work properly?
Yes
Go to the next step.
No
Repair or replace the malfunctioning part according to the inspection results, then go to Step 20.
16
INSPECT PURGE SOLENOID VALVE OPERATION
•  Turn the ignition switch off.
•  Connect the vacuum pump to purge solenoid valve and apply vacuum to solenoid.
•  Verify that the solenoid holds vacuum.
•  Turn the ignition switch to the ON position (engine off).
•  Perform the Simulation Function Procedure and access the EVAPCP PID.
•  Set the duty value to 100% for EVAPCP PID.
•  Apply vacuum while turning solenoid from OFF to ON and simulating the EVAPCP PID with 100% duty value.
•  Verify that solenoid releases vacuum while solenoid is turned ON.
•  Is the purge solenoid valve operation normal?
Yes
Go to the next step.
No
Replace the purge solenoid valve, then go to Step 20.
(See PURGE SOLENOID VALVE REMOVAL/INSTALLATION [L8, LF].)
17
INSPECT EGR VALVE OPERATION
•  Remove the EGR valve.
•  Visually inspect the EGR valve for stuck to open.
•  Is the EGR valve stuck to open?
Yes
Repair or replace the EGR valve, then go to Step 20.
(See EGR VALVE REMOVAL/INSTALLATION [L8, LF].)
No
Go to the next step.
18
INSPECT SEALING OF ENGINE COOLANT PASSAGE
•  Perform the “ENGINE COOLANT LEAKAGE INSPECTION.”
•  Is there any malfunction?
Yes
Repair or replace the malfunctioning part according to the inspection results, then go to Step 20.
No
Go to the next step.
19
INSPECT PCV VALVE OPERATION
•  Turn the ignition switch off.
•  Inspect the PCV valve.
•  Is the PCV valve operation normal?
Yes
Go to the next step.
No
Replace the PCV valve, then go to the next step.
20
VERIFY DTC TROUBLESHOOTING COMPLETED
•  Make sure to reconnect all disconnected connectors.
•  Turn the ignition switch to the ON position (engine off).
•  Clear the DTC from the PCM memory using the M-MDS.
•  Perform the KOER self test.
•  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.
21
VERIFY AFTER REPAIR PROCEDURE
•  Perform the “AFTER REPAIR PROCEDURE”.
•  Are any DTCs present?
Yes
Go to the applicable DTC troubleshooting.
(See DTC TABLE [L8, LF].)
No
DTC troubleshooting completed.