Testing a misfire code (P0300, P0301, P0302, P0303, P0304) isn't hard and I'll explain some of the testing tips and techniques that are performed to get the bottom of the misfire code and misfire condition.
The info in this article applies to the GM 2.2L 4 cylinder equipped Chevrolet Cavalier, or Pontiac Sunfire, or Chevrolet Sonoma, or GMC Sonoma.
Here are the contents of this article at a quick glance:
A misfire condition, in plain English, describes an engine that is not operating on all cylinders. Now, in the case of the GM 2.2L 4 cylinder engine, if one cylinder cuts out, the engine will only output 75% of it's power... and this will cause some issues. If two or more engine cylinders are misfiring, your vehicle will not start. Here are some of the most common symptoms of a misfire condition on your GM 2.2L:
As you may already know, each cylinder needs air, fuel, and spark to produce power. If any one of these components are missing, that engine cylinder will misfire. Therefore, the fault could lie in the ignition system (which is responsible for creating spark), or in the fuel system. Now, in most cases... it's usually a lack of spark that's to blame for the misfire, but not always. Let's take a brief look at the different things that can cause your 2.2L to misfire...
Ignition System: As you're already aware, the ignition system on the GM 2.2L is composed of an ignition module, two ignition coils (that feed two cylinders with spark simultaneously), 4 spark plug wires, and 4 spark plugs. If any one of these goes BAD (and they do), then you'll end up with a misfire condition. Now, all of these can be tested to see if they are the culprits behind the misfire.
Here are the most common ignition system problems causing a misfire:
Fuel System: Here are the most common fuel system component failures:
Engine Mechanical Condition: An engine cylinder that is not producing enough compression, even it has the spark and fuel, will cause a misfire condition that will set a misfire code. Another thing that will cause a misfire (normally at idle) is vacuum leaks coming from a large vacuum hose or the Intake Manifold Gasket.
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