Engine Misfire Code P0300 - P0308

The powertrain control module (PCM) uses information from the ignition control (IC) module and the camshaft position (CMP) sensor in order to determine when an engine misfire is occurring. By monitoring the variations in the crankshaft rotation speed for each cylinder the PCM is able to detect individual misfire events.

A misfire rate that is high enough can cause the three-way catalytic converter to overheat under certain conditions. The malfunction indicator lamp (MIL) will flash ON and OFF when the conditions for three-way catalytic converter overheating are present.

Misfire can be caused by a faulty spark plug, plug wire, ignition coil, fuel injector, or internal engine mechanical problem. Step by step diagnosis is required to determine what system is causing the misfire.

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  • Guest - joyce

    hhrchevrolet checking engine light on an off

  • Guest - Lacee

    I have an 84 gmc sierra classic 1500 350 v8 holly 600 4 barrel carburetor. When it's idiling it runs fine when shifted into gear it idles rough and I press the accelerater it starts bogging and spits and sputters and hesitates to go. I've already tried replacing the spark plugs and wires distributior cap and rotor. And rebuilt the carburetor.

  • Guest - MIKE


  • Guest - Bill

    Timing specs for 1991 Grand Prix GTP.


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