Even a small number of misfires may result in excessive exhaust emissions due to the unburned fuel mixture. Increased misfire rates will cause damage to the catalytic converter. The PCM monitors variations in the crankshaft rotation speed to determine if misfires occur. The PCM identifies the specific cylinder in which the misfire has occurred and counts individual misfire events by monitoring changes in the crankshaft rotation speed for each cylinder. A random misfire indicates two or more cylinders are misfiring.
Item | Detecting Condition | Possible Cause | |
DTC Strategy |
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Determine if a multiple cylinder misfire or a cylinder specific misfire is occurring by monitoring crankshaft rotation speed. | 1. Faulty Spark plugs 2. Faulty Spark plug cables 3. Air Leakage 4. Belt deflection and Air gap of CKPS 5. Incorrect timing 6. Faulty injector 7. Improper fuel pressure 8. Improper engine compression | |
Enable Conditions | No disabling faults present / no disabling Active Faults
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P0340 / P0341 / P0118 / P0117 / P0115 / P0336 / P0335 / P1295 P0103 / P0102 / 0108 / P0107 / P0106 / P0501
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Engine speed between 550 and 5800 RPM
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System voltage between 9V and 18V
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The ECT indicates an engine temperature between -6℃(20℉) and 120℃(248℉) | ||
Threshold value | Case 1 |
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Individual cylinder misfire detection | |
Case 2 |
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Emissions damaging - 18 times in 600 ignitions(In case that the misfire affects more than 1.5 times than the Federal Test Procedure (FTP) tailpipe standard) | ||
Case 3 |
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Catalyst damaging - 95 times in 600 ignitions at idle (It is going to be changeable according to the load or the temperature which is not in the range where it does not melt catalyst) | ||
Diagnosis Time |
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Continuous | ||
MIL On Condition |
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3 Driving Cycles | ||
