P0301
DTC P0301 CYLINDER 1-MISFIRE DETECTEDComponent Location:
COMPONENT LOCATION
GENERAL DESCRIPTION
Misfires can be caused by lack of combustion in a cylinder due to absence of spark, poor fuel metering, poor compression, or many other causes. Even a small number of misfires may result in excessive exhaust emissions due to the unburned mixture. Increased misfire rates cause damage to the catalytic converter. The PCM monitors the crankshaft speed variation to determine if any misfiring generated. The PCM identifies the specific cylinder in which the misfire has occurred and counts individual misfire events by monitoring changes in the crankshaft rotation for each cylinder. A random misfire indicates two or more cylinders are misfiring.
DTC DESCRIPTION
If misfire occurs in cylinder #1, the PCM determines that a fault exists and a DTC is stored.
DTC Detecting Condition:
Schematic Diagram:
MONITOR SCANTOOL DATA
1. Ignition "OFF"
2. Connect Scantool and Engine "ON"
Specifications:
3. Monitor HO2S parameter and parameters related to Fuel System Too Lean on CURRENT DATA.
Specification:
Engine RPM at idle: 700 ± 100 rpm
Ignition Timing: BTDC 7° ± 5°
4. Are the parameters related to Fuel System Too Lean displayed within specifications?
YES: Fault is intermittent caused by poor contact in the sensor's and/or PCM's connector or was repaired and PCM memory was not cleared. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure.
NO: Go to "System Inspection" procedure.
SYSTEM INSPECTION
1. Check Spark Plug Cable
1. Visually/physically inspect the following items:
- Damage, cracks and flashover
2. Measure the resistance of the spark plug cable
Specification: 4.48 - 6.72 kOhms/m(3.28 ft) at 20 °C (68 °F)
3. Is the measured resistance within specifications?
YES: Go to "Check Spark Plug" as below.
NO: Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure.
2. Check Spark Plug
1. Remove cylinder's spark plugs
2. Visually/physically inspect the following items:
- Damaged insulation, Worn electrodes, Oil or fuel fouled, Loose terminals and cracks
- Check for plug gap: 1.0 - 1.1 mm (0.039 - 0.043 in.)
- Check if the spark plug for the relevant cylinder is lighter in color than the other plugs.
3. Has found a problem in any of the above areas?
YES: Repair or replace as necessary and g9 to "Verification of Vehicle Repair" procedure.
NO: Go to " Check Air Leakage " as below.
3. Check Air Leakage
1. Visually/physically inspect the air leakage in intake/exhaust system as following items,
- Vacuum hoses for splits, kinks and improper connections.
- Throttle body gasket.
- Gasket between intake manifold and cylinder head.
- Seals between intake manifold and fuel injectors.
- Exhaust system between HO2S and Three way catalyst for air leakage.
2. Has a problem been found in any of the above areas?
YES: Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure.
NO: Go to "Check for air leakage in Positive Crankcase Ventilation Valve(PCV).
4. Check for air leakage in Positive Crankcase Ventilation Valve(PCV)
1. Remove PCV valve from cylinder head cover by puling ventilation hose.
2. With engine idling block PCV valve opening.
3. Verify that vacuum is felt.
4. Remove PCV valve.
5. Blow through valve from port "A" and verify that air comes out of port "B"
6. Blow through valve from port "B" and verify that no air comes out of port "A"
7. Has a problem been found?
YES: Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure.
NO: Go to "Check Compression pressure" as below.
5. Check Compression pressure
1. Warm up the engine to normal operating temperature.
2. Disconnect the spark plug cables and remove the spark plugs.
3. Crank the engine to remove any foreign material in the cylinders.
4. Put compression pressure gauge into spark plug hole.
5. Crank the engine with widely opened throttle valve and check compression pressure at each cylinder.
Specification: 1,200 kPa (12.2 kg/sq.cm,170 psi)
6. Is compression pressure for each cylinder displayed within specifications?
YES: Go to "Check Timing belt deflection and Air Gap for CKPS" as below.
NO:
- Add a small amount of oil through the spark plug hole, and repeat above steps.
If the addition of oil causes the compression to rise, the cause is a worn or damaged piston ring or cylinder inner surface
- If the compression remains the same, the cause is a burnt or defective valve seat, or pressure is leaking from the gasket.
Repair as necessary and go to "Verification vehicle Repair" procedure.
6. Check Timing belt deflection
1. Check timing belt deflection and deflection pressure.
Specification: Deflection: 0.2 - 0.27 in (5.0 - 7.0mm)
2. Is the timing belt deflection within the specifications?
YES: Go to "Check Timing" as below.
NO: Repair or replace as necessary and then, go to "Verification of Vehicle Repair" procedure.
7. Check Timing
1. Ignition "OFF"
2. Check that Cam, Crank and Oil pump sprocket timing marks are correctly in alignment.
3. Monitor signal waveform from CAM and Crank shaft position Sensor are correctly in alignment.
4. Are all timing marks aligned correctly?
YES: Go to "Check Fuel Pressure Test" as below.
NO: Repair or readjust as necessary and go to "Verification of Vehicle Repair" procedure.
8. Fuel Pressure Test
NOTE:
1. Be cautious that Fuel is explosive and an empty fuel tank can still contain explosive gases.
When working on fuel system make sure to supply adequate ventilation to the work area. Do not smoke, and keep sparks and open flames away
2. The fuel system remains under pressure when the engine is not running. Release fuel system pressure before disconnecting any fuel line to reduce the chance of personal injury or fire damage to vehicle components.
1. Check the fuel for excessive water, alcohol, or other contaminants. Replace contaminated fuel as necessary.
2. Install the fuel pressure gauge to the fuel pressure gauge adaptor.
3. Apply battery voltage to the terminal for the pump drive and activate the fuel pump: then, with fuel pressure applied, check that there is no fuel leakage from the pressure gauge or connection part.
4. Disconnect the vacuum hose from the pressure regulator, and plug the hose end.Measure the fuel pressure at idle.
Specification: 320 - 340 kPa (3.26 - 3.47 kg/sq.cm, 46 - 49 psi)
5. Measure the fuel presure when the vacuum hose is connected to the pressure regulator.
Specification: Approx. 255 kPa (2.57 kg/sq.cm, 37 psi)
6. Are the measured fuel pressure within specifications?
YES: Go to "Check injector leakage" as below.
NO: Repair or replace according to the below table. And then, go to "Verification of Vehicle Repair"procedure.
9. Check Injector Leakage
1. Ignition "OFF" after checking the Fuel Pressure Test.
2. Stop the engine and check for a change in the fuel pressure gauge reading for 5 minutes.
3. Does fuel pressure retain after engine is stopped?
YES:
- Substitute with a known - good PCM and check for proper operation.
- If the problem is corrected, replace PCM and go to "Verification of Vehicle Repair" procedure.
NO: Repair or replace according to the below table. And then, go to "Verification of Vehicle Repair" procedure.
VERIFICATION OF VEHICLE REPAIR
After a repair, it is essential to verify that the fault has been corrected.
1. Monitor and record the Freeze Frame Data for the Diagnostic Trouble Code(DTC) which has been diagnosed.
2. Using a Scantool, Clear the DTCs.
3. Operate the vehicle within conditions noted in the freeze frame data or enable conditions.
4. Monitor that all readiness tests have been verified as "Complete"
5. Are any DTCs present?
YES: Go to the applicable troubleshooting procedure.
NO: System is performing to specification at this time.