P0304

P0304 Cylinder 4 - Misfire Detected

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 two or more cylinders are misfiring.

Detecting Condition & Limp Home:

DTC DETECTING CONDITION

1. DTC Description
The ECM must monitor the engine for misfiring possibly caused by ignition coil defects or injector fails. If misfiring is detected, the ECM identify the cylinder(s) that has(have) misfired and calculate misfiring rate for a given duration. The DTC for Misfire (P0301 to 0304) is set as soon as misfiring rate exceed the limit which result in damage to the catalyst or increase emissions.The ECM stores individual DTC for the cylinder which has more than 10% of total misfire rate With more than two cylinders misfire detection, the ECM sets P0300. If the misfire rate is not extremely high, the MIL will be illuminated in the next driving cycle that diagnostic runs and fails. With extremely high misfire rate which has a danger of burning up the catalyst, the MIL blinks immediately.

2. Conditions for Setting the DTC

Specification:

Schematic Diagram:

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Step 7 - 8:

Inspection Procedure