DTC P0300 [AJ] (VIN: JM0 LW10J300 301406-, JMZ LW69J7*# 307683-, JM8 LW28J**# 301514-, JM8 LW28A**# 301514- (Assumed))

BME010200100W08

DTC P0300

Random misfire detection

DETECTION CONDITION

• PCM monitors CKP sensor input signal interval time. PCM calculates the change of the interval time for each cylinder. If the change of interval time exceeds the preprogrammed criteria, PCM detects a misfire in the corresponding cylinder. While the engine is running, PCM counts the 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, PCM determines that a misfire, which can damage the 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 misfire which can damage the catalytic converter during first drive cycle.
• PENDING CODE is available if the PCM detects the above malfunction condition during the first drive cycle.
• FREEZE FRAME DATA is available.
• DTC is stored in the PCM memory.

POSSIBLE CAUSE

• CKP sensor malfunction
• CMP sensor malfunction
• Ignition coil malfunction
• Ignition system malfunction
• Mass airflow sensor contamination
• Excess air suction in intake air system (between mass air flow sensor and dynamic chamber)
• Fuel pump malfunction
• Fuel pressure regulator malfunction
• Fuel line clogged
• Fuel filter clogged
• Fuel leakage in fuel line
• Fuel runout
• Poor quality fuel
• Purge control solenoid valve malfunction
• PCV valve malfunction
• EGR valve malfunction
• Vacuum hoses damages or improper connection
• Related connector and terminal malfunction
• Related wiring harness malfunction

Diagnostic procedure

STEP

INSPECTION

ACTION

1
VERIFY FREEZE FRAME DATA AND DIAGNOSTIC MONITORING TEST RESULTS HAVE BEEN RECORDED
• Have FREEZE FRAME DATA and DIAGNOSTIC MONITORING TEST RESULTS (Misfire related) been recorded?
Yes
Go to the next step.
No
Record FREEZE FRAME DATA and DIAGNOSTIC MONITORING TEST RESULTS on repair order, then go to the next step.
2
VERIFY RELATED SERVICE INFORMATION AVAILABILITY
• Check for related Service Information availability.
• Is any related Service Information available?
Yes
Perform repair or diagnosis according to available Service Information.
• If vehicle is not repaired, go to next step.
No
Go to next step.
3
VERIFY RELATED PENDING CODE OR STORED DTCs
• Turn the ignition switch off then ON (Engine OFF).
• Verify related pending code or stored DTCs.
• Is other DTCs present?
Yes
Go to appropriate DTC troubleshooting.
No
Go to next step.
4
VERIFY CURRENT INPUT SIGNAL STATUS (IGNITION SWITCH TO ON/IDLE)
• Access ECT, IAT, MAF, RPM, TP, and VSS PIDs using WDS or equivalent.
• Is there any signal that is far out of specification when ignition switch is ON and engine runs at idle?
Yes
Inspect suspected circuit and/or part according to inspection results.
Then go to Step 21.
No
Go to next step.
5
VERIFY CURRENT INPUT SIGNAL STATUS UNDER TROUBLE CONDITION
• Inspect PID while simulating FREEZE FRAME DATA condition.
• Is there any signal which causes drastic changes?
Yes
Inspect suspected circuit and/or part according to inspection results.
Then go to Step 21.
No
Go to next step.
6
INSPECT CMP SENSOR
• Inspect CMP sensor.
• Is CMP sensor normal?
Yes
Go to next step.
No
Inspect installation condition and damages on timing belt and gears, repair faulty parts.
• If it is normal, replace CMP sensor.
Then go to Step 21.
7
VERIFY CKP SENSOR INSTALLATION CONDITION
• Check for CKP sensor looseness.
• Is CKP sensor loosen?
Yes
Retighten CKP sensor, then go to Step 21.
No
Go to next step.
8
CHECK IGNITION COIL OPERATION
• Perform spark test.
(See Spark Test)
• Do all cylinders show blinking condition?
Yes
Go to step 11.
No
Go to next step.
9
INSPECT POWER SUPPLY TERMINAL AT IGNITION COIL CONNECTOR
• Disconnect ignition coil connector.
• Turn the ignition switch to ON (Engine OFF).
• Measure voltage between ignition coil terminal D (harness-side) and body ground.
• Is there voltage reading B+?
Yes
Go to next step.
No
Check for open circuit between ignition coil connector and ignition switch. Repair or replace wiring harness, then go to Step 21.
10
INSPECT IGNITION COIL RESISTANCE
• Check ignition coil resistance.
• Is coil resistance normal?
Yes
Go to step 21.
No
Replace ignition coil, then go to Step 21.
11
INSPECT MAF PID
• Start engine.
• Access MAF PID using WDS or equivalent.
• Verify that MAF PID changes quickly according to race engine RPM.
• Is MAF PID response normal?
Yes
Go to next step.
No
Replace mass airflow sensor, then go to Step 21.
12
INSPECT EXCESSIVE AIR SUCTION IN INTAKE AIR SYSTEM
• Inspect for air leakage at following:
- Between mass air flow sensor and throttle body
- Between throttle body and dynamic chamber
• Is there any malfunction?
Yes
Repair or replace suspected part, then go to Step 21.
No
Go to next step.
13
INSPECT FUEL LINE PRESSURE
• Inspect fuel line pressure.
• Is fuel line pressure normal?
Yes
Go to step 17.
No
If fuel line pressure is too low, go to next step.
If fuel line pressure is excess high, check as follows:
• Fuel pump maximum pressure
• Fuel return line for clogged
- If all above are normal, replace pressure regulator.
Then go to Step 21.
14
INSPECT FUEL PUMP MAXIMUM PRESSURE
• Inspect fuel pump maximum pressure.
• Is fuel pump maximum pressure normal?
Yes
Go to next step.
No
Inspect fuel pump circuit for open or poor connection. Repair or replace suspected circuit, then go to Step 21.
• If normal, replace fuel pump, then go to Step 21.
15
INSPECT FUEL LINE FROM FUEL PUMP TO FUEL DELIVERY PIPE
• Visually inspect for fuel leakage in fuel line for any leakage.
• Is any fuel leakage found?
Yes
Replace suspected fuel line, then go to Step 21.
No
Inspect fuel filters for following:
• Restriction or clogging at fuel filter (high-pressure side).
• Foreign materials or stain inside fuel filter (low-pressure side)
Perform following actions as result.
• If restriction or clogging is found at fuel filter (high-pressure side), replace fuel filter.
• If foreign materials or stain is found inside fuel filter (low-pressure side), clean of fuel tank and filter.
• If all items above are normal, replace pressure regulator.
Then, go to Step 21.
16
INSPECT ENGINE COMPRESSION
• Inspect engine compression.
• Is it normal?
Yes
Go to next step.
No
Implement engine overhaul for repairs, then go to Step 21.
17
INSPECT OPERATION OF PURGE CONTROL SOLENOID VALVE
• Perform purge solenoid valve inspection.
• Is purge control solenoid valve normal?
Yes
Go to next step.
No
Replace purge control solenoid valve, then go to Step 21.
18
INSPECT PCV VALVE OPERATION
• Turn the ignition switch off.
• Remove PCV valve and check valve operation.
• Is PCV valve operation normal?
Yes
Replace PCV valve, then go to Step 21.
No
Go to next step.
19
INSPECT OPERATION OF EGR VALVE
• Remove EGR valve.
• Visually check for stuck to open.
• Does EGR valve stuck to open?
Yes
Go to next step.
No
Repair or replace EGR valve, then go to Step 21.
20
INSPECT SEALING OF ENGINE COOLANT PASSAGE
Warning
• Removing radiator cap when radiator is hot is dangerous. Scalding coolant and steam may shoot out and cause serious injury.
• When removing radiator cap, wrap thick cloth around and turn it slowly.
• Remove radiator cap.
• Implement procedure to bleed air from engine coolant, then run engine at idle.
• Is there any small bubble which makes engine coolant white at filling opening?
Note
• Large bubbles are normal since they are remaining air coming out from engine coolant passage.
Yes
Air gets in from poor sealing on head gasket or other areas between combustion chamber and engine coolant passage. Repair or replace faulty parts, then go to next step.
No
Go to next step.
21
VERIFY TROUBLESHOOTING OF MISFIRE DTC COMPLETED
• Make sure to reconnect all disconnected connectors.
• Turn the ignition switch to ON (Engine OFF).
• Clear DTC from memory using WDS or equivalent.
• Run PCM adaptive memory procedure drive mode.
• Is PENDING CODE of same DTC present?
Yes
Replace PCM, then go to next step.
No
Go to next step.
22
VERIFY AFTER REPAIR PROCEDURE
• Perform "After Repair Procedure".
• Is there any DTC present?
Yes
Go to applicable DTC inspection.
No
Troubleshooting completed.