The ignition coil is a critical component in small engines, such as those found in Echo power equipment like chainsaws, trimmers, and blowers. It transforms low-voltage power from the engine's stator into the high voltage necessary to create a spark at the spark plug, thus igniting the air-fuel mixture in the cylinder. Understanding the resistance of an ignition coil is crucial for diagnosing starting and running problems in these engines. When an engine fails to start or runs poorly, testing the ignition coil resistance is a standard troubleshooting step. An Echo ignition coil resistance chart provides a reference for the expected resistance values, allowing technicians and DIYers to quickly assess whether the coil is within acceptable specifications.
What is Ignition Coil Resistance?
Ignition coil resistance refers to the opposition to the flow of electrical current within the coil's windings. It's measured in ohms (Ω) using a multimeter. There are typically two resistance measurements taken on an ignition coil:
Primary Resistance
The primary resistance is the resistance of the primary winding, which is the lower-voltage winding connected to the engine's ignition module or points. This winding consists of relatively few turns of thicker wire. The primary resistance is typically very low, usually less than a few ohms. A typical range might be 0.5 to 3 ohms, but this varies greatly depending on the specific Echo model and ignition system.
The secondary resistance is the resistance of the secondary winding, which is the high-voltage winding connected to the spark plug. This winding consists of many turns of very thin wire. Consequently, the secondary resistance is significantly higher than the primary resistance, often ranging from several thousand to tens of thousands of ohms (kΩ). A common range is 3,000 to 15,000 ohms, but again, this depends on the Echo model and coil design.
An incorrect resistance reading – either too high or too low – indicates a potential problem with the coil, such as shorted windings, open circuits, or insulation breakdown.
Why Use an Echo Ignition Coil Resistance Chart?
An Echo ignition coil resistance chart is a valuable diagnostic tool because it provides the specific, model-dependent resistance values that the ignition coil should exhibit when functioning correctly. Without this chart, it's difficult to know if a measured resistance value is within the acceptable range. Using the wrong coil for a specific application, or using a coil outside of its specified resistance will damage your engine. The chart eliminates guesswork and allows for accurate diagnosis.
Accuracy: Provides precise resistance values for specific Echo models, ensuring accurate diagnosis.
Efficiency: Speeds up the troubleshooting process by providing a known good reference.
Cost Savings: Helps identify a faulty coil before replacing other potentially good components.
Prevents Further Damage: Using a faulty coil can damage other components, such as the ignition module (CDI) or the engine itself.
Where to Find Echo Ignition Coil Resistance Charts
Finding an accurate and reliable Echo ignition coil resistance chart is essential. Here are several resources:
Echo Service Manuals: The official Echo service manual for your specific model is the most reliable source. These manuals contain detailed specifications, including ignition coil resistance values. They are typically available for purchase from Echo dealers or online retailers.
Online Forums and Communities: Online forums dedicated to small engine repair and Echo equipment can be valuable resources. Experienced users often share information and resistance values they have measured. However, always verify information from online forums with other sources, as accuracy can vary.
Repair Websites: Some websites specializing in small engine repair provide troubleshooting guides and specifications, including ignition coil resistance values. Again, cross-reference the information with other sources to ensure accuracy.
Local Echo Dealers: Your local Echo dealer can often provide resistance specifications for your particular model. They have access to official Echo documentation and technical information.
Important Note: Always make sure the chart you are using is specifically for your Echo model. Using the wrong values can lead to misdiagnosis and unnecessary parts replacement.
How to Test Ignition Coil Resistance
Testing ignition coil resistance requires a digital multimeter (DMM). Here's a step-by-step guide:
Safety First: Disconnect the spark plug wire from the spark plug. Ensure the engine is off and cool.
Prepare the Multimeter: Set the multimeter to the ohms (Ω) setting. For the primary resistance test, use the lowest ohms range (e.g., 200 Ω). For the secondary resistance test, use a higher ohms range (e.g., 20 kΩ or 200 kΩ).
Test the Primary Resistance: Connect the multimeter probes to the two terminals on the primary side of the ignition coil (typically the terminals where the wires from the ignition module connect). Record the reading.
Test the Secondary Resistance: Connect one multimeter probe to the spark plug terminal on the ignition coil and the other probe to ground (typically the metal mounting bracket of the coil). Record the reading. Some coils have a dedicated ground terminal; connect the probe to that terminal instead.
Compare to Chart: Compare the measured resistance values to the specifications in the Echo ignition coil resistance chart for your model.
Interpret the Results:
Within Range: If the measured resistance values are within the specified range, the ignition coil is likely good.
Too Low: A resistance value that is significantly lower than specified may indicate a short circuit within the windings.
Too High or Open Circuit: A resistance value that is significantly higher than specified or an "OL" (overload) reading on the multimeter indicates an open circuit within the windings.
Caution: Always consult your multimeter's manual for specific instructions on measuring resistance. Ensure your multimeter is properly calibrated for accurate readings.
How To Test Ignition Coil Ohms - YouTube
Troubleshooting Based on Resistance Readings
Here's how to interpret resistance readings and possible causes:
Low Primary Resistance (Significantly Lower Than Specified)
Possible Causes: Shorted windings in the primary coil, internal coil failure.
Action: Replace the ignition coil.
High Primary Resistance or Open Circuit
Possible Causes: Broken wire in the primary winding, corroded terminals, internal coil failure.
Action: Inspect terminals and wiring for corrosion or damage. If wiring is intact, replace the ignition coil.
Echo ignition coil - YouTube
Low Secondary Resistance (Significantly Lower Than Specified)
Possible Causes: Shorted windings in the secondary coil, carbon tracking inside the coil, insulation breakdown.
Action: Replace the ignition coil.
High Secondary Resistance or Open Circuit
Possible Causes: Broken wire in the secondary winding, carbon tracking inside the coil, faulty spark plug connector, internal coil failure.
Action: Inspect the spark plug connector and wire for damage. If intact, replace the ignition coil.
Kohler Ignition Coil / Module Testing - YouTube
Resistance Within Specified Range, but Still No Spark
Possible Causes: Even if the resistance is within range, the coil can still be faulty under load. Other possible causes include a faulty ignition module (CDI), a problem with the air gap between the coil and the flywheel, a damaged flywheel key, or a faulty kill switch.
Action: Check the ignition module, air gap, flywheel key, and kill switch. Consider replacing the ignition coil as a process of elimination, even if the resistance is within range.
Important Note: Resistance testing is just one aspect of diagnosing ignition system problems. Always consider other potential causes, such as fuel delivery issues or mechanical problems.
Beyond Resistance: Other Ignition Coil Tests
While resistance testing is a primary method for evaluating ignition coils, other tests can provide further insights:
Spark Test: Visually check for a strong, blue spark at the spark plug when the engine is cranked. A weak or non-existent spark indicates a potential ignition problem. (Caution: Avoid touching the spark plug wire while cranking, as it carries high voltage).
Air Gap Measurement: Ensure the correct air gap between the ignition coil and the flywheel. The specification is typically very small (e.g., 0.010 - 0.020 inches). Use a feeler gauge to verify the gap.
Voltage Test (If Applicable): On some ignition systems, you can test the voltage output of the ignition module. Refer to the service manual for instructions.
Conclusion
Understanding and utilizing an Echo ignition coil resistance chart is a fundamental aspect of diagnosing and repairing small engine problems in Echo power equipment. By accurately measuring the primary and secondary resistance of the ignition coil and comparing the values to the chart, technicians and DIYers can quickly determine if the coil is functioning correctly, saving time, money, and preventing further damage to the engine. While resistance testing is a valuable diagnostic tool, it should be used in conjunction with other troubleshooting methods to ensure a comprehensive assessment of the ignition system.
