If the ECM detects that engine speed variation indicates a misfire sufficient to cause three-way catalyst converter damage or emissions level to exceed standard value, the ECM sets misfire DTC. If the misfire rate is high enough to damage the catalyst, the MIL will flash to alert the vehicle operator. With a more than two cylinder misfire detection, the ECM sets P0300.
Item | Detecting Condition | Possible Cause | |
DTC Strategy |
•
Signal monitoring | 1. Poor connector connection 2. Incorrect valve timing 3. Uneven compression 4. Air leakage 5. Improper fuel pressure or dirty fuel 6. Blocked/leaking injectors 7. Faulty injectors | |
Enable Condition | Case 1 |
•
Engine speed is at between 400rpm and 4520rpm
•
Engine load is higher than zero torque line | |
Case 2 |
•
Negative torque change is less than 0% per sec.
•
Intake air temperature is higher than -8.3℃(17)℉
•
Engine coolant temperature is higher than -8.3℃(17)℉ | ||
Threshold Value | Case 1 |
•
Multi-cylinder misfire rate per revolution is greater than 5.0% (Related in emission threshold) | |
Case 2 |
•
Multi-cylinder misfire rate per 200 revolutions is greater than 6.0% ~ 25% depends on operating region (Related in catalyst damage) | ||
Diagnostic Time | Case 1 |
•
1000 revolution | |
Case 2 |
•
200 revolution | ||
MIL ON Condition | Case 1 |
•
3 driving cycles | |
Case 2 |
•
Immediately (Blink) | ||
