This will article will help you to understand some of the most common causes of Misfires and Misfire Codes (P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0307, P0308) on the GM 4.3L, 5.0L and 5.7L equipped pick ups and SUVs.
I'm also gonna' offer you a simple diagnostic strategy (one I've used with a lot of success) and guide you to the test articles you'll need to get to the bottom of your misfire or rough idle issue.
Here are the main points of this article. You can start at the beginning or click on each heading (below) and go directly to it:
A Misfire Condition, in non technical terms simply describes an engine that is not running on all cylinders.
This condition is also best described by other common terms: ‘Engine has a dead cylinder’ or ‘Engine has a miss’ or ‘Engine has a rough idle’.
Whether your GM vehicle has a V6 or a V8, if one cylinder or two cut out, it won't run on 100% Engine power and this will cause some of the following consequences (symptoms):
What complicates things a little further, is that your specific vehicle may come equipped with a TBI (Throttle Body Injection) or a CPI (Central Port Injection) or a CSFI (Central Sequential Fuel Injection) fuel system... but in reality, all of the misfires, irrespective of the type of fuel or ignition system, have common root causes. Let's turn the page and learn more...
Since quite a few things can cause and Engine to Misfire, we need to understand the basics of what each Engine Cylinder needs to create power. Now, don't worry, I won't go into minute technical detail... just the basics (and in plain English) that you need to troubleshoot your Misfire issue.
The most important thing you need to know is that each cylinder needs air, fuel, and spark to produce power. So, let's take a look at how each one is delivered to the the Engine:
Ignition System: The Ignition System is responsible for the production and delivery of Spark. The Ignition System is usually the culprit behind a Misfire.
The usual suspects (that cause a misfire, rought engine idle, engine miss, ‘dead’ cylinder, etc.) are:
The good news is that all of the components that make up the Ignition System can be tested, and at the end of the article I'll show you where to find the How To Test articles.
Continued in the next page...