How To Test A Misfire Condition and Misfire Codes on Honda 2.2L, 2.3L

Having worked on cars as a professional tech for about 20+ years now , I can tell you that I love working on Hondas! Why? For the simple fact that they are very easy to troubleshoot and repair (whenever something goes wrong that is) and troubleshooting a misfire condition is no exception.

Since so many different things can cause a misfire condition on your 2.2L or 2.3L Honda... in this tutorial, I'm gonna' share some of the hands-on experience and knowledge I've acquired over the years in the interest of helping you find the source of the misfire without a lot of time, effort and frustration.

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

What is a Misfire Condition?

Simply put, a misfire condition is a condition in which the engine in your Honda is not running on all cylinders. Since the 2.2L (and 2.3L) is a 4 cylinder, having just one cylinder misfire will cause a problem. Having two or more... and your Honda probably won't run

Here are the most common symptoms of a misfire:

  1. The Check Engine Light will be on.
  2. One or more Misfire Codes (P0300-P0308) will be stored in your Honda'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.

It's pretty cool that an OBD II equipped vehicle can give us a specific misfire code... what stinks, is that it doesn't tell you what specific component is bad. On a pre-OBD II vehicle, there is no misfire trouble code diagnostic help coming from the fuel injection computer.

What's gonna' help to get to the bottom of the misfire (or rough idle condition), whether you have a misfire code or not, is knowing what is the root cause of a misfire. Let's move on to the next subheading and we'll find out more...

What Causes A Misfire Condition?

To successfully diagnose a misfire code or condition, we need to know that each cylinder needs 3 very specific things to run/operate at their peak. If one of these 3 things is missing... then that specific engine cylinder will go ‘dead’. These 3 things are:

  1. Air
  2. Fuel
  3. Spark

With this important bit of knowledge under our belts, 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) are:

  1. BAD spark plugs.
  2. BAD spark plug wires.
  3. Carbon tracks on the spark plug and spark plug boot.
  4. BAD distributor cap.
  5. Oil dripping (from the valve cover) onto the spark plugs and spark plug boots.

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.

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.

Engine Mechanical Condition: The pistons and cylinder head valves are the ones that draw air into the engine, and these bad boys eventually wear out.

Generally, all 4 engine cylinders wear out evenly... but not always. In some vehicles, you'll have one or more cylinder (and its related components) wear out at an accelerated pace. When this happens, those cylinders (with accelerated wear and tear)tend to produce a less than average compression value that will cause a misfire condition.

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