Part 1
2UR-GSE ENGINE CONTROL: SFI SYSTEM: P0300: Random / Multiple Cylinder Misfire Detected
DTC P0300 - Random / Multiple Cylinder Misfire Detected
DTC P0301 - Cylinder 1 Misfire Detected
DTC P0302 - Cylinder 2 Misfire Detected
DTC P0303 - Cylinder 3 Misfire Detected
DTC P0304 - Cylinder 4 Misfire Detected
DTC P0305 - Cylinder 5 Misfire Detected
DTC P0306 - Cylinder 6 Misfire Detected
DTC P0307 - Cylinder 7 Misfire Detected
DTC P0308 - Cylinder 8 Misfire Detected
DESCRIPTION
When the engine misfires, high concentrations of hydrocarbons (HC) enter the exhaust gas. Extremely high hydrocarbons concentration levels can cause an increase in exhaust emission levels. High concentrations of hydrocarbons can also cause increases in the three-way catalytic converter temperature, which may cause damage to the three-way catalytic converter. To prevent this increase in emissions and to limit the possibility of thermal damage, the ECM monitors the misfire count. When the temperature of the three-way catalytic converter reaches the point of thermal degradation, the ECM blinks the MIL. To monitor misfires, the ECM uses both the camshaft position sensor and the crankshaft position sensor. The camshaft position sensor is used to identify any misfiring cylinders and the crankshaft position sensor is used to measure variations in the crankshaft rotation speed. Misfires are counted when the crankshaft rotation speed variations exceed predetermined thresholds.
If the misfire exceeds the threshold levels and may cause emission deterioration, the ECM illuminates the MIL and sets a DTC.
If DTCs that indicate misfires are set for different cylinders, but DTC P0300 is not set, it indicates that misfires have been detected in different cylinders at different times. DTC P0300 is only set when several misfiring cylinders are detected at the same time.
MONITOR DESCRIPTION
The ECM illuminates the MIL and sets a DTC when either one of the following conditions, which could cause emission deterioration, is detected (2 trip detection logic):
- Within the first 1000 crankshaft revolutions of the engine starting, an excessive misfire count (approximately 20 to 50 misfires per 1000 crankshaft revolutions) occurs once.
- After the first 1000 crankshaft revolutions, an excessive misfire count (approximately 20 to 60 misfires per 1000 crankshaft revolutions) occurs 4 times in sequential crankshaft revolutions.
The ECM flashes the MIL and sets a DTC when either one of the following conditions, which could cause the three-way catalytic converter damage, is detected (2 trip detection logic):
- In every 200 crankshaft revolutions at a high engine rpm, the threshold misfire percentage is recorded once.
- In every 200 crankshaft revolutions at a normal engine rpm, the threshold misfire percentage is recorded 3 times.
MONITOR STRATEGY
TYPICAL ENABLING CONDITIONS
Misfire
Monitor Period of Emission-Related Misfire
Monitor Period of Catalyst-Damaging Misfire (MIL Blinks)
TYPICAL MALFUNCTION THRESHOLDS
Monitor Period of Emission-Related Misfire
Monitor Period of Catalyst-Damaging Misfire (MIL Blinks)
MONITOR RESULT
Refer to Checking Monitor Status Mode 6 Data.
CONFIRMATION DRIVING PATTERN
1 Connect the Techstream to the DLC3.
2 Turn the engine switch on (IG).
3 Turn the Techstream ON.
4 Record the DTC(s) and freeze frame data.
5 Using the Techstream, switch the ECM from normal mode to check mode Check Mode Procedure.
6 Read the misfire counts of each cylinder (Cylinder #1 Misfire Count to Cylinder #8 Misfire Count) with the engine in an idling condition. If any misfire count is displayed, skip the following confirmation driving pattern.
7 Drive the vehicle several times with the conditions, such as engine rpm and engine load, shown in Misfire RPM and Misfire Load in the Data List.
HINT:
- In order to store misfire DTCs, it is necessary to operate the vehicle for the period of time shown in the table below, using the Misfire RPM and Misfire Load in the Data List.
8 Check whether misfires have occurred by checking DTCs and freeze frame data.
HINT: Do not turn the engine switch off until the stored DTC(s) and freeze frame data have been recorded. When the ECM returns to normal mode (default), the stored DTC(s), freeze frame data and other data will be erased.
9 Record the DTC(s), freeze frame data and misfire counts.
10 Turn the engine switch off and wait for at least 5 seconds.