How To Test Ignition Coil 2 Stroke

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How To Test Ignition Coil 2 Stroke – The ignition system of a two-stroke engine consists of a coil, a switch, a module, a flywheel with magnets and a spark plug with its wires.

When the lever connected to the starter is pulled to start the engine, the flywheel with the magnet in the engine block begins to turn. When the magnets pass in front of the coil, it creates a spark at the spark plug, which allows the air-fuel mixture to ignite in the combustion chamber.

When the engine is switched on, the ignition system continues to rotate and brings the flywheel magnet with it. The scenario therefore repeats itself every time the magnets pass in front of the coil, and the spark plug continues to discharge electricity.

All this does not happen by chance; it actually respects a very precise rhythm where each element intervenes in a coordinated way. Therefore, combustion always takes place when the compression level of the engine reaches its maximum level.

How To Test Ignition Coil 2 Stroke

In this article, you will find information about the operating principle of the ignition coil, its role, as well as tips for learning how to test an ignition coil and replace it.

How Does The Ignition Coil Work?

Although there are different types of ignition coils depending on the make and power of the engine, their role is the same for all engines.

The ignition coil consists of an iron core around which there is a secondary winding and a primary winding.

The secondary winding is a coil of insulated copper wire composed of 50,000 windings with a thickness of approximately 0.05 to 1 mm. The primary winding is wound on the secondary winding and is made of a stronger lacquered copper wire with a thickness of approx. 0.6-0.9 mm.

The ignition coil is connected to the motor by means of three terminals located at the end of the coil: the power supply, the switch and the high voltage connection.

The switch is connected to the primary and secondary windings and can turn on or off the current flowing in the primary winding.

As the current passes through the switch, it accelerates, changing the magnetic field in the coil. This change in the magnetic field makes it possible to cause a voltage pulse which, when it passes through the secondary winding, is converted into a high voltage pulse.

The high voltage pulse continues its path via the ignition cable to the spark plug, where it makes it possible to cause the spark that will be able to allow combustion of the air-fuel mixture in a 2-stroke engine.

How To Test Ignition Coil 2 Stroke



Your safety and the safety of others is important. Before tampering, make sure the device is turned off and the plug is unplugged. It is also recommended to wear gloves to protect your hands as well as comfortable clothing close to the body and to remove jewelry and accessories that may be stuck.

Before we get to the heart of the matter, let’s start by looking at the symptoms and causes that can lead to ignition coil failure.

What are the symptoms of a defective ignition coil?

In the event of a malfunction of the ignition coil, here are the elements that need to be observed on your device to confirm your diagnosis:

  • Your machine’s engine does not start, or
  • When starting, the engine has difficulty starting, or
  • During operation, the engine experiences power loss, or
  • An engine light comes on.

A problem with starting or coughing in the engine when the mower is running does not necessarily come from a spool problem. For more information, see the following article: My Lawn Mower Does Not Start, What Should I Do?

How do you know if your ignition coil is bad

Now that you know the symptoms, let’s take a look at the causes. For as the old saying goes, “prevention is better than cure”, and what good is it to replace the coil if it fails again shortly after due to a fault in another part? On your device.

How do you check an ignition coil

How To Test Ignition Coil 2 Stroke? The contact

Poor contact is often due to the presence of moisture in the ignition coil. This can happen when the unit is cleaned or if the unit is stored incorrectly during the winter.

How To Test Ignition Coil 2 Stroke: The Cable

A fault in the power supply may be due to a defective cable or an unsuitable or excessively worn battery. This can cause premature wear on the ignition system.

How To Test Ignition Coil 2 Stroke: Short circuit

An internal short circuit may be due to normal wear of the unit or a malfunction of the ignition system. This will cause the coil to overheat. In this case, the coil has black-burning marks on the power terminal.

How To Test Ignition Coil 2 Stroke: A damaged mechanical part

Sometimes the spark plugs have been nibbled by mice, or the gaskets are too worn for the spark plug to leak. Either way, this will damage the spark plug and prevent the spark from appearing properly.

Test ignition coil with a multimeter

How to test the ignition coil with a multimeter It is possible to use a multimeter to check the condition of the ignition coil. It is also the most reliable method currently known and recommended by all professionals, which makes it possible to establish an accurate fault diagnosis.

How To Test Ignition Coil 2 Stroke
  1. Remove the protective cover from the mower.
  2. Remove the cord from the spark plug.
  3. Remove the spark plug using a spark plug wrench.
  4. Using a multimeter in the Ohmmeter position and set to 20 k, place the multimeter’s needles as follows: The positive wire must be in the usual location of the spark plug in contact with the plug, the negative wire must be in contact with the metal part of the ignition coil. This makes it possible to measure the value of the coil.
  5. Read and interpret the result on the multimeter. A work coil must produce a result of between 2.5 and 5 K Ohms. If the multimeter shows no value, it means that the coil has failed and needs to be replaced.

Following the classic multimeter method, it is possible to use a more artisanal technique to check the condition of the ignition coil.

Although this second method does not make it possible to give an exact value, it makes it possible to indicate on the coil whether it is functional or not. However, the implementation of this test may pose a risk. It is therefore important to protect your hands well before proceeding with this check.

  1. Remove the protective cover from the mower.
  2. Remove the cord from the spark plug.
  3. Remove the spark plug using a spark plug wrench.
  4. Connect the spark plug to the cable and place the other end of the spark plug (thread) against a metal part of the engine.
  5. Start the mower and observe the reaction of the spark plug. If it produces sparks of blue color, it indicates that the coil is working. Otherwise, check the condition of the spark plug and replace it as well as replace the ignition coil.

Test ignition coil with a Battery

There is a final test to check the condition of the ignition coil. This is done with a battery. This may not be the most reliable technique, but it does give you an idea of ​​the condition of the coil. In general and whenever possible, it is advisable to confirm these results with a multimeter.

  1. When the bulb is out of place, connect the positive lead of the battery to the positive terminal of the coil. Then connect the negative lead of the battery to the spark plug and then the coil.
  2. Observe the spark plug if a spark occurs, it means that the ignition coil is working. On the contrary, if nothing happens, it may be due to a malfunction in the spark plug or coil that needs to be replaced.

On any petrol vehicle, the spool plays a crucial role. In addition to starting the vehicle properly, it guarantees an optimal air-fuel mixture in the combustion chamber, which prevents over-consumption of fuel, which also makes it possible to take advantage of a less polluting vehicle.

In addition, a defective coil can cause premature wear on the car’s catalytic converter or lambda sensor. It is therefore recommended to perform a regular auto-diagnosis of your vehicle.

  1. Remove the engine protection cover from the car, motorcycle or moped to be tested.
  2. Remove a connector from the ignition coil with a coil puller.
  3. Unplug the spool by gently pulling the plug.
  4. Disconnect the plug to separate the coil from the rest of the motor.
  5. Observe the general condition of the coil for cracks or signs of burns. If the coil does not look damaged, continue the test, otherwise replace it.
  6. Connect the coil to the plug and place a grounded test spark plug (attached to a metal part of the engine) on the coil.
  7. Switch on the ignition of the car, motorcycle or moped.
    If the coil is in good condition, the test spark plug will produce blue sparks, otherwise replace it.
How To Test Ignition Coil 2 Stroke

How to test your spark plugs

The coil cannot work if the machine spark plug does not work. When checking the ignition coil, it is therefore very important to also check the condition of the spark plug.

  1. Remove the spark plug using a spark plug wrench.
  2. Observe its condition and color. A light in good condition will be light brown. If the spark plug is black, it indicates that the carburetor setting is too rich. If the light is greasy, it is from the mixture that contains too much oil.
  3. Sometimes it is possible to clean the spark plug with a cloth to restore it to working condition. So start by cleaning it to restore it to its original color, if this does not work, replace it.
  1. Separate the starter from the mower.
  2. Observe the engine to locate the ignition coil, it can be recognized because it is connected to the spark plug. See the service manual that came with the device for the exact location of the spool.
  3. Disconnect the spark plug cable.
  4. Tighten the screws that secure the bobbin fixing system.
  5. Lift the part thus unscrewed to remove the spool from its position.
  6. Use pliers to disconnect the plug connected to the spool to disconnect the spool from the motor.
  7. To assemble the new coil, first reconnect the coil connector and then put it back in place with the screws. Finally connect the cable connected to the spark plug.

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