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 ECM monitors the crankshaft speed variation to determine if any misfiring generated. The ECM 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 one or more cylinders are misfiring.
DTC Description
If there happen misfires over the threshold value at #1 cylinder, ECM sets DTC P0301.
DTC Detecting Condition
Item | Detecting Condition | Possible Cause |
DTC Strategy | Engine roughness through crankshaft speed fluctuation
| Poor connection Ignition system Fuel system Intake/exhaust air system Ignition timing Injector |
Enable Conditions | Time after engine start > 25sec.
No error on CKPS
No rough road driving condition
No fuel-cut condition
|
Threshold Value | Misfire rate / cylinder > 10% of total misfire rate(emission threshold) or > 25% of total misfire rate(catalyst damage threshold)
|
Diagnostic Time | Continuous
|
MIL ON Condition | 3 driving cycle
|