Tutorials To Help You Find The Cause Of The Misfire
If you've performed the manual cylinder balance test and have found a ‘dead’ cylinder, then you might be asking yourself: “What's next?”.
The next part is to find out what's causing the cylinder to misfire. This means finding out which of the 3 basic things (the cylinder needs to work) is missing. These 3 basic things are: 1.) Spark, 2.) Fuel, 3.) Air.
To further help you along, in your troubleshooting, here are some more specifics:
- Things that can prevent spark from reaching the cylinder:
- Bad ignition coil.
- Bad ignition coil cover (plastic part coils are housed in).
- Bad spark plug.
- Bad spark plug boot.
- Engine oil leaking onto the spark plugs from cylinder covers.
- Things that can prevent fuel from reaching the cylinder:
- Bad fuel injector.
- fuel injector not being activate by PCM or due to a short in the wiring.
- Things that can prevent air from reaching the cylinder:
- 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):
- Test the ignition system first.
- The ignition system is usually the culprit behind most of the misfire (‘dead’ cylinder) conditions.
- You can find an in-depth tutorial on how to test the ignition coil packs here: How To Test The Ignition Coils GM 2.4L Quad 4 (at: easyautodiagnostics.com).
- Test the fuel injectors second.
- 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.
- You can find an in-depth tutorial on how to do a fuel injector resistance test here: How To Test The Fuel Injectors (GM 2.4L Quad 4).
- Test the engine compression third.
- 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.
- You can find an in-depth tutorial on how to test your Quad-4's compression here: How To Test Engine Compression (GM 2.4L Quad 4).
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).
If this info saved the day, buy me a beer!
