What Tests Can I Perform To Find The Cause Of The Misfire Condition?
It's been my experience that the key to success, in finding the exact cause of a misfire condition is to first identify the cylinder that's ‘dead’.
After identifying the ‘dead’ cylinder, the next steps are to do specific tests. The following diagnostic/troubleshooting strategy has helped me a lot and I think it'll help you too:
STEP 1: Identify the ‘dead’ cylinder. If your vehicle is OBD II equipped, this usually means retrieving the misfire diagnostic trouble codes. Then by matching the misfire code to its engine cylinder using an illustration of the engine cylinders.
This of course, doesn't apply to every situation, especially if you have a pre-OBD II equipped vehicle or an OBD II equipped Honda that refuses to register a misfire code or codes. In this case, you'll need to do a manual cylinder balance test and this is how it's done:
- Removed the metal locking clips from all four injectors.
- Started the engine.
- Unplugged one fuel injector at a time to see if it had any effect on the engine idle. You'll have one of 2 results:
- CASE 1: If the cylinder is ‘dead’ to begin with, unplugging its fuel injector will not cause any drop in the engine's RPMs.
- CASE 2: If the cylinder is NOT ‘dead’, unplugging its fuel injector will definitely cause a drop in the engine's RPMs causing the engine to idle rougher (shake more).
Once you've identified the ‘dead’ cylinder, the next steps are:
STEP 2: Test the ignition system first. Since the majority of misfires are caused by a failed component in the ignition system, you should:
- Perform a spark test (using a dedicated spark tester) on the spark plug wire of the cylinder that the misfire code is accusing of being dead.
- Testing for spark with a spark tester is the most important first test since you'll know right away if the misfire is due to a lack of spark.
- Check to see if the spark plug boots and spark plugs are swimming in engine oil from a leaking valve cover gasket.
- If you got spark from your spark tester (from the cylinder the misfire code is accusing of misfiring), the next step is to remove the spark plug or spark plugs (of the affected cylinders) and check them for wear and tear, carbon tracks, anti-freeze, etc.
- The following tutorials will help you test the ignition system:
- How To Test The Igniter, Ignition Coil Accord, Civic, CRV, and Odyssey For Hondas with the ignition coil inside the distributor (at: easyautodiagnostics.com).
- How To Test The Igniter, Ignition Coil Accord, Prelude (1992-2001) For Hondas with the ignition coil outside the distributor (at: easyautodiagnostics.com).
STEP 3: Test the fuel injectors. If testing the ignition system tells you that the problem is somewhere else, then the next step is to check the fuel injectors.
You'll need to:
- Resistance test each of the 4 fuel injectors.
- Do a Noid light test of each one to make sure the PCM is pulsing them (activating them).
- You can find the fuel injector tests here:
STEP 4: Test the compression of each engine cylinder. Other tests that should be done, if the ignition system and fuel injectors check out OK are:
- Engine compression test.
- Checking for vacuum leaks.
- You can find the engine compression test here:
The above list of steps may seem/sound like troubleshooting a misfire is a complicated thing but it really isn't. Depending on your level of ‘wrenching’ experience, this is something that you can accomplish without taking it to the shop.
What Tools Do I Need To Test The Misfire Code(s)?
Finding the exact cause of the misfire codes or misfire condition is possible with the proper tools. Without them, you won't be able to diagnose/troubleshoot those issues on your 2.2L or 2.3L Honda car or mini-van.
Depending on what the root cause of the misfire is, you may need several tools. Most of these you can buy online, none of these will break the bank and I'll make some recommendations on them. Here's a guide to some of the basic tools that can be and are used:
- Ignition System Tests:
- Spark tester.
- 12 Volt test light.
- Fuel System Tests:
- Noid light.
- Fuel pressure gauge.
- Engine Mechanical Tests:
- Compression tester.
Now of course, you'll also need basic hand tools like: screw-drivers, ratchet wrenches, sockets, etc. You'll also need a generic scan tool to retrieve the diagnostic trouble codes (DTCs) from the computer's memory.
Keep in mind that using the right tool for the job will save you time, frustration, and /or keep you from damaging the component that you're testing.
Whether or not your Honda vehicle is OBD II equipped or not, you can find the exact cause of the misfire with the right troubleshooting strategy.
The most important thing to remember is that you need to identify the ‘dead’ cylinder first. Once you've done this, the rest is easy.
Take advantage of the other tutorials I've written since I've written all of them from practical every day experience and tailored for the home mechanic (the typical DIY'er - Do It Yourself'er). You can find them here:
If this info saved the day, buy me a beer!