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 PCM monitors the crankshaft speed variation to determine if any misfiring generated. The PCM 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
The PCM measures reference event times and calculates the positive and negative acceleration of the crank wheel to detrmine whether a misfire has occurred.
When the rate of misfire exceeds a threshold where the catalyst reaches a temperature where permanent damage can ocur, to the point that tail pipe emissions reach 1.5 times the tailpipe standard or where a cylinder misfire cause a loss of torque produced from that cylinder. PCM sets this DTC. In case that misfire affects Catalyst damage, MIL(Malfunction Indicatin Lamp) will be illuminating and blinking at 1HZ frequency. However, In case of Indivisual and Emission damaging misfire, MIL will be turned on when the malfunction is detected.
Especially, if injector connector / Ignition coil is disconnected for more than 46 sec., PCM sets DTC relating to misfire and conducts the fuel-cut to protect the catalyst.
DTC Detecting Condition
Item | Detecting Condition | Possible Cause |
DTC Strategy | ? Determine if a multiple cylinder misfire or a cylinder specific misfire is occurring by monitoring crankshaft acceleration. | ? Faulty Spark plugs ? Faulty Spark plug cables ? Air Leakage ? Belt deflection and Air gap of CKPS ? Incorrect timing ? Faulty injector ? Improper fuel pressure ? Improper engine compression |
Enable Condition | No disabling faults present / no disabiling Active Faults ? P0340 / P0341 / P0118 / P0117 / P0115 / P0336 / P0335 / P1295/P0103 / P0102 / 0108 / P0107 / P0106 / P0501 ? Engine speed between 550 and 5800 RPM ? System voltage between 9 and 18 volts ? The ECT indicates an engine temperature between -6?(20?) and 120?(248?) |
Threshold Value | Case1 | ? Individual cylinder misfire detection |
Case2 | ? Emissions damaging - 18 times in 600 ignitions(In case that the misfire affects more than 1.5 times than FTP emissins) |
Case3 | ? 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 | ? Continuous |
MIL On Condition | ? 2 driving cycles |