How To Test Misfire Codes (Chrysler 2.0L, 2.4L)

A misfire code or misfire condition can have one of several root causes... for example: bad spark plug wires, a bad fuel injector, low engine compression. Unfortunately, this list of ‘possible’ bad components can grow quite a bit, which makes it seem like it's almost impossible to find the cause of the misfire or rough idle condition on your Chrysler 2.0L or 2.4L equipped vehicle.

The good news is that testing a misfire code, or misfire codes, or a rough idle condition is not that hard and it's something you can do!

In this tutorial, I'm going to explain in some detail the most common causes of misfires and misfire codes (P0300, P0301, P0302, P0303, P0304) and more importantly, I'm also gonna' offer you a simple diagnostic strategy that I'm certain will help you ‘nail down’ the cause of the misfire condition, misfire code, or rough idle condition your Honda is experiencing.

Let's get started by jumping right into the next subheading...

What is a Misfire Condition?

In layman's terms, a misfiring cylinder is a cylinder that's ‘dead’, either because it's missing fuel, or spark, or air.

Since the 2.0L and 2.4L engines have only 4 cylinders, having just one of those cylinders misfire will have pretty obvious consequences due to the fact that the engine in your Chrysler is running on only 3 cylinders. If the engine in your car has one or two misfiring cylinders, you'll have one or more of the following symptoms:

  1. The Check Engine Light will be on.
  2. One or more Misfire Codes (P0300-P0308) will be stored in your Chrysler's PCM memory.
    1. P0300 Random Cylinder Misfire.
    2. P0301 Cylinder #1 Misfire.
    3. P0302 Cylinder #2 Misfire.
    4. P0303 Cylinder #3 Misfire.
    5. P0304 Cylinder #4 Misfire.
  3. Sometimes, even tho' the engine is suffering a bona-fide misfire, no misfire codes are registered and no Check Engine Light (CEL) comes on.
  4. Lack of power upon acceleration.
  5. Smell of unburned gas exiting the tail pipe.
  6. Rough idle and may stall.
  7. Cranks but does not start.
  8. Will not pass the emissions tests.
  9. Bad gas mileage.

Although the misfire codes don't tell you what exactly is the cause of the misfire or rough idle condition... there is a way to find out exactly what is causing it.

One of the most important things you need to know, to successfully diagnose a misfire or rough idle condition, is what causes a misfire. Let's go to the next subheading and find out.

What Causes A Misfire Condition?

Each engine cylinder needs 3 things to be able to produce power. In a nutshell, these 3 things are:

  1. Air
  2. Fuel
  3. Spark

It's when one of these three things is missing from the mix that the engine in your 2.0L or 2.4L Chrysler starts to misfire. Let's look into more specifics:

Ignition System: The ignition system is responsible for the production and delivery of spark. The Ignition System is usually the culprit behind most misfires.

The usual suspects (that cause a misfire) are:

  1. BAD spark plugs.
  2. Carbon tracks on the spark plug and spark plug boot.
  3. BAD Coil-on-Plug (COP) ignition coil.
  4. Oil dripping (from the valve cover) onto the spark plugs and COP ignition coil boots.

Testing all of the ignition system components is not hard and it doesn't require expensive tools or expensive diagnostic equipment. The following tutorial should help you with detailed testing info to see if you have bad spark plug wires or a bad ignition coil pack:

  1. How To Test The Coil Pack (Chrysler 2.0L, 2.4L) (at: easyautodiagnotics.com).
  2. Carbon Tracks Are A Common Cause Of Ignition Misfires (at: easyautodiagnotics.com).

Fuel System: The fuel system is responsible for the delivery of Fuel. If fuel is missing from any one specific engine cylinder, it will misfire.

fuel system problems could include some of the following:

  1. BAD fuel injectors.
  2. Broken fuel injector connector (this is a very, very common problem).
  3. Electrical short in the fuel injector wires that are keeping the fuel injector pulse signal from reaching the fuel injector.
    1. This is usually the result of human error and after a major mechanical repair where the wiring harness was damaged.
  4. BAD Fuel Injection Computer not pulsing the fuel injector (this is a very rare condition, but it happens).
  5. BAD fuel pump.

The following tutorial should be of help:

  1. How To Test A Fuel Injector (Chrysler 2.0L, 2.4L).

Engine Mechanical Condition: The Pistons and Valves are the ones that draw air into the engine. Usually all cylinders wear out evenly... but every now and then, either thru' lack of maintenance or some mechanical problem, you'll have one or more wear out at an accelerated pace.

To make the long story short, those cylinders (with accelerated wear and tear) to produce a less than average compression value that will cause a misfire condition.

Other issues, that can not be overlooked are vacuum leaks.

Check out this tutorial:

  1. How To Test The Engine Compression (Chrysler 2.0L, 2.4L).