How To Troubleshoot a Misfire (Suzuki 1.3L, 1.6L, 1.8L, 2.0L, 2.3L)

A misfire can be a challenge to diagnose, since a misfire can be caused by a number of different things.

That's right, anything from a fouled spark-plug to burned cylinder head valves can cause a misfire. Whatever the root cause of the misfire, the bottom line is that one or more cylinders are not contributing to total engine power output. This leads to power loss, rough idle, unstable RPM and bad gas mileage.

In this article, I'll talk about the most common causes of a misfire and I'll show you a specific diagnostic strategy that'll help you track down and solve the issue.

Symptoms Of A Misfire

One of the core symptoms of a misfire is a rough idle but this isn't the only symptom you'll experience. Here are some more that you might see:

1. Check engine light is on with the one or several of the following diagnostic trouble codes:
   • P0300: Random Cylinder Misfire.
   • P0301: Cylinder #1 Misfire.
   • P0302: Cylinder #2 Misfire.
   • P0303: Cylinder #3 Misfire.
   • P0304: Cylinder #4 Misfire.
2. Really bad gas mileage.
3. Lack of power.
4. Engine may start, run for a few minutes and stall.
5. Smell of raw gasoline coming out of the tail-pipe.

Basic Causes Of A Misfire Condition

There are three major areas that are prone to causing a misfire condition, and thus misfire codes, on your Suzuki with a 1.3L or 1.6L Engine. These are:

1. The fuel system.
2. The ignition system.
3. The engine (piston, cylinder, and cylinder head valves).

As you're already aware, the engine needs three very specific things to start and they are: air, fuel and spark.

When things are working like they should, each cylinder gets the same amount of air, fuel and spark. So, it's when one of these three components is missing, from one or two cylinders, that the engine experiences a misfire.

In the next couple of headings, I'll dissect each system and see what specific components (of each) are the ones that are usually responsible for a misfire condition and misfire codes.

With And Without Misfire Codes

A misfire that lights up the check engine light (CEL) with one of the following codes: P0301, P0302, P0303, P0304 is a misfire that is fairly easy to troubleshoot and diagnose, since the PCM (Powertrain Control Module = Fuel Injection Computer) has identified the engine cylinder with the problem.

What the diagnostic trouble code doesn't tell you is exactly what has failed (like a COP coil, or a fuel injector, or engine compression).

The hard-to-diagnose misfires are usually the ones that set a P0300 Random Misfire Code (since the misfire is affecting all of the four cylinders) or ones that don't set a diagnostic trouble code at all.

No matter if you have a specific cylinder misfire code or no codes at all, the underlying cause is still a lack of ignition, or fuel (lean fuel mixture) or an engine mechanical problem (think vacuum leaks, compression, etc).

Let's turn the page and we'll take a look at what you'll need to do to pinpoint and resolve the issue causing the misfire.

Ignition System: Misfire Troubleshooting

Since the ignition system is usually the culprit behind most misfire conditions, this is where you should start your basic tests.

Here are my suggestions:

1. Check for misfire codes with a scan tool.
   • The misfire code will let you know which cylinder is the one that's dead.
   • If no codes are present or you have a P0300, then you'll need to do a cylinder balance test.
     • The cylinder balance test should be done by unplugging the electrical connector of the fuel injector or the COP coil.
2. Physically inspect things.
   • Check the spark plugs for:
     • Cracks.
     • Engine oil (from a leaking valve cover gasket).
     • Fuel fouling.
     • Center electrode capped/blocked with carbon.
     • Check for carbon tracks on the ceramic insulator.
   • Check the COP coils or spark plug wires for:
     • Cracks or burns on the rubber boot that connects/surrounds the spark plug.
     • Engine oil (from a leaking valve cover gasket).
     • Carbon tracks on the inside of the rubber boot.
   • Check the distributor cap (on distributor type ignition systems) for:
     • Engine oil (from a leaking from the internal distributor shaft seal).
     • Cracks and/or carbon tracks on the inside the cap.

3. Test for spark.
   • Use a dedicated spark tester.
     • Doing a spark test with anything other than a spark tester (like pulling the COP coil or spark plug wire from the spark plug) can and will damage the ignition coil.
     • Using a timing light will only have you wasting your time and money since this is the MOST INACCURATE way to test for spark.

If no issues are found in the ignition system, the next step is to see if a fuel system issue is causing the cylinder misfire. Go to: Fuel System: Misfire Troubleshooting.