System Inspection

P0300 Random/Multiple Cylinder Misfire Detected

Inspection/Repair - System Inspection

System Inspection

Spark plug check
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 a problem been found in any of the above areas?





Compression pressure check
1. Warm up the engine to normal operating temperature.
2. Disconnect the spark plug cables. And remove the spark plugs and fuel pump relay.
3. Crank the engine to remove any foreign material in the cylinders.
4. Put compression pressure gauge into spark plug hole.
5. Check compression pressure at each cylinder.

Specification : Approx. 15 kg/cm2

6. Is compression pressure for each cylinder displayed within specifications?





Ignition system check
1. IG KEY "OFF".
2. Disconnect Ignition coil connector.
3. Do visual inspection.
> Check contamination or damage on ignition coil.
4. IG KEY "ON" & ENG "OFF"
5. Measure the voltage between power terminal of ignition coil #1, #2, #3, #4 harness connector and chassis ground.

Specification : B+




6. Is the measured voltage within specifications?





Ignition coil check
1. Measure the resistance between power and control terminal of ignition coil connector #1, #2, #3, #4. (Component side / Primary coil)
Specification :









2. Is the measured resistance within specifications?





Timing mark check
1. IG KEY "OFF".
2. Check the timing mark.
3. Is the timing mark normal?





Air leakage check
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?





PCV (Positive Crankcase Ventilation) valve check
1. IG KEY "OFF".
2. Disconnect PCV valve.
3. Check the movement of plunger by putting in and out a thin stick.
4. Is the movement of plunger normal?





Injector check
1. IG KEY "OFF".
2. Remove injectors.
3. Check leakage or clog on injectors.
4. Measure the resistance between power and control terminal of the injector. (Component side)
Specification :









5. Is the measured resistance within specification?





Fuel line check
1. Check clog, contamination and damage on fuel line.
> Splits, kinks and improper connections of fuel line pipe.
> Interference, damage and improper connections of vacuum hose on fuel line.
> Improper connection of connectors on fuel line.
2. Is the fuel line normal?





Fuel pressure check
1. IG KEY "OFF".
2. Disconnect a fuel pump relay.
3. Engine start and wait until engine stop. and then key "OFF".
4. Install fuel pump relay.
5. Connect fuel pressure gauge using the correct adaptor.
6. Start the engine, and record fuel pressure.

Specification : Approx. 3.5 kg/cm2




7. Is the fuel pressure normal?