In this article, I'm gonna' shed some light on how to troubleshoot Misfire Codes (P0300, P0301, P0302, P0303, P0304) on your Nissan Altima (or Frontier, Xterra) with the 2.4L 4 cylinder engine.
You'll learn some of the most common causes of a misfire condition and more importantly, where to find the test articles to solve the misfire issue.
Contents of this tutorial:
What Is A Misfire Condition?
In lay man's terms, a misfire condition, simply describes an engine that isn't running on all cylinders. On the 2.4L Nissan 4 cylinder engine, if just one cylinder goes dead (for whatever reason), you are gonna' feel it since your engine is now running on 75% power.
If two engine cylinders are misfiring... your car will have a very hard time staying running, not to mentioning you'll have no power to drive it down the road. Here are some of the most common symptoms of a misfire condition:
- The check engine light will be on.
- One or more misfire codes (P0300, P0301, P0302, P0303, P0304) will be stored in the car or pick up's computer's memory.
- P0300 Random Cylinder Misfire.
- P0301 Cylinder #1 Misfire.
- P0302 Cylinder #2 Misfire.
- P0303 Cylinder #3 Misfire.
- P0304 Cylinder #4 Misfire.
- Misfire is present, but no misfire codes are registered in the computer's memory and/or no check engine light (CEL) on.
- Lack of power upon acceleration.
- Smell of unburned gas exiting the tail pipe.
- Rough idle and may stall.
- Cranks but does not start.
- Will not pass the emissions tests (smog check).
- Bad gas mileage.
What Causes A Misfire Condition?
There are three very important components that each cylinder, in your engine, needs to be able to produce power and they are: air, fuel and spark. If any one of these is missing, the specific cylinder that is being affected will go dead (not produce power).
This means that the misfire could be caused by a fault in the fuel system, or in the ignition system, or an engine mechanical condition. 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 Nissan 2.4L engine to misfire...
Ignition System: If any one engine cylinder is not getting spark because a BAD spark plug, BAD spark plug wire, BAD Distributor Cap, etc... you'll have a bona-fide misfire on your hands. At the end of this article you'll find the links to the test articles that'll show you how to test these parts.
Fuel System: If fuel is missing from any one specific engine cylinder, it will misfire. The most common cause of this missing fuel, is a BAD fuel injector (and fuel injectors can easily be tested).
Engine Mechanical Condition: One of the most overlooked causes of a misfire is a worn out engine cylinder. This extreme wear and tear will cause a lower than normal compression condition that no matter what gets replaced.. your Nissan will continue to misfire. The best way to check for this, is by doing an engine compression test and comparing the compression readings of all 4 cylinders to each other.
Another thing that will cause a misfire (normally at idle) is vacuum leaks coming from a large vacuum hose or the intake manifold gasket. Another common cause, is oil leaking onto the spark plug tubes and coating the spark plug wire boot and spark plug with engine oil.