If the PCM detects that engine speed variation indicates a misfire sufficient to cause three-way catalyst converter damage or emissions level to exceed standard value, the PCM 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 PCM sets P0300.
Item | Detecting Condition | Possible Cause |
DTC Strategy |
•
Calculation of engine roughness | 1. Faulty spark plugs or Ignition coil 2. Incorrect valve timing 3. Uneven compression 4. Air leakage 5. Improper Fuel pressure or dirty fuel. 6. Blocked/Leaking injectors 7. Leakage between cooling system and cylinder |
Enable Conditions |
•
Engine load ratio :14~64%
•
500< Engine speed(rpm) <6700
•
Mass air flow gradient/sec. :12~60%
•
Throttle gradient/sec. : 0.5~10.5%
•
Coolant temperature >20℃(68℉) if start temp. <-7℃(19℉)
•
No relevant failure
•
Fuel cut-off not active
•
11V< Battery voltage <16V | |
Threshold Value |
•
Misfire detected on 2 or more cylinders | |
Diagnostic Time |
•
Continuous | |
Mil On Condition |
•
Immediate (Misfire enough to damage the catalyst)
•
2 Driving Cycles (Misfire breaking the emission regulation) |
