Misfire Troubleshooting Guide

Each cylinder needs air, fuel, and spark to produce power. So, when an engine cylinder is misfiring, it's missing one of these 3 key ingredients.

This also means that the 3 areas the misfire is most likely to occur are:

  1. Ignition system. Components that can cause a misfire are:
    1. BAD distributor cap.
    2. BAD spark plug.
    3. BAD spark plug wire.
    4. BAD oil leaking onto the spark plugs from the valve cover.
  2. Fuel system. Components that can cause a misfire are:
    1. BAD fuel injector.
    2. Fuel injector not getting activation pulses. Either because the PCM is bad or there's a short in the wiring between it and the PCM.
  3. Engine Mechanical. Problems that can cause a misfire:
    1. Low engine compression.

The above list may seem like troubleshooting a ‘dead’ (misfiring) cylinders is hard but with a good diagnostic strategy, you'll be able to find the root cause of the misfire.

Here are my suggestions (and the diagnostic strategy I use):

  1. Test the Ignition System first.
    1. The Ignition System is usually the culprit behind most of the misfire (‘dead’ cylinder) conditions.
    2. The following tutorial will help you test the ignition system on your 1.5L Honda Civic: How To Test The Igniter, Ignition Coil Accord, Civic, CRV, and Odyssey (at: easyautodiagnostics.com).
  2. Test the fuel injectors second.
    1. After eliminating the Ignition System as the cause of the misfire, the next step is to make sure that the fuel injector is not fried internally.
    2. The following tutorial will help you do a fuel injector resistance test: How To Test The Fuel Injectors (1992-1995 1.5L Honda Civic).
  3. Test the engine compression third.
    1. After making sure that the ignition system is providing Spark and the fuel injector is injecting fuel into the ‘dead’ cylinder, the next step would be to check that cylinder's compression.
    2. The following tutorial will help you do an engine compression on your 1.5L Honda Civic: How To Test Engine Compression (Honda 1.5L).

The above list of tests can be modified to suit your particular diagnostic, troubleshooting needs (since there really isn't a specific cookie cutter way of diagnosing a car).