Stihl Ignition Coil Resistance Chart (5 Essential Testing Tips)

The user intent is to learn how to test a Stihl chainsaw ignition coil using a resistance chart and other essential testing tips. They likely want to diagnose ignition problems and determine if the coil needs replacement.

Understanding the Importance of a Healthy Ignition Coil

Before diving into the specifics of testing, let’s understand why the ignition coil is so crucial. The ignition coil is essentially a transformer that takes the low voltage from your chainsaw’s magneto and boosts it to thousands of volts. This high voltage is then sent to the spark plug, creating the spark that ignites the fuel-air mixture in the cylinder, powering your saw.

A weak or failing ignition coil can lead to several problems, including:

• Hard starting: The saw might take many pulls to start, or it might not start at all.
• Erratic running: The engine might run rough, misfire, or stall frequently.
• Loss of power: The saw might lack the power needed to cut through wood effectively.
• Complete failure: The saw simply won’t start.

Deciphering the Stihl Ignition Coil Resistance Chart

The resistance chart is your key to understanding whether your coil is within the acceptable range. Because Stihl produces a wide range of chainsaw models, specific resistance values can vary. Therefore, always consult the service manual for your specific Stihl chainsaw model for the correct resistance values.

Why Resistance Matters:

Resistance is the opposition to the flow of electrical current. A healthy ignition coil has a specific resistance range in both its primary and secondary windings. If the resistance is too high (open circuit) or too low (short circuit), the coil is likely faulty.

Typical Resistance Values (General Guide Only – Consult Your Manual):

• Primary Winding: The primary winding is the low-voltage side of the coil. Typical resistance values here are very low, often less than 1 ohm (Ω). Some coils might read 0.5 ohms, others 0.8 ohms. It is crucial to have a precise reading for your specific model.
• Secondary Winding: The secondary winding is the high-voltage side of the coil. Resistance values here are much higher, typically ranging from a few thousand ohms to tens of thousands of ohms (e.g., 2,000 – 10,000 Ω). Again, your service manual is the ultimate authority.

Using the Chart for Diagnosis:

1. Locate the Correct Chart: Find the resistance chart for your specific Stihl chainsaw model in the service manual. These manuals are often available online or through your local Stihl dealer.
2. Identify Primary and Secondary Windings: The chart will specify which terminals on the coil correspond to the primary and secondary windings.
3. Measure Resistance: Use a multimeter (explained in detail below) to measure the resistance between the specified terminals.
4. Compare to Chart Values: Compare your measured resistance values to the values listed in the chart.
5. Interpret Results:
   • Within Range: If the resistance values are within the specified range, the coil is likely good.
   • Too High (Open Circuit): This indicates a break in the winding, and the coil needs to be replaced.
   • Too Low (Short Circuit): This indicates a short circuit within the winding, and the coil needs to be replaced.
   • Zero Resistance: This can also indicate a short circuit or a complete failure of the winding.

My Personal Experience:

I once spent an entire afternoon wrestling with a Stihl MS 290 that refused to start. After checking the fuel, spark plug, and air filter, I finally decided to test the ignition coil. The resistance readings were way off – the secondary winding showed almost no resistance. Replacing the coil solved the problem instantly. This experience drilled home the importance of systematically checking the ignition coil when troubleshooting starting issues.

5 Essential Testing Tips for Stihl Ignition Coils

Here are five essential tips to ensure accurate and effective testing of your Stihl ignition coil:

Tip 1: Using a Multimeter – Your Diagnostic Tool

A multimeter is an essential tool for testing electrical components, including ignition coils. Here’s how to use it:

1. Set the Multimeter to Ohms (Ω): Select the ohms setting on your multimeter. You might need to select a specific range, such as 200 ohms for the primary winding and 20k ohms for the secondary winding. Refer to your multimeter’s manual for specific instructions.
2. Connect the Leads: Connect the multimeter leads to the appropriate terminals on the ignition coil. For the primary winding, connect the leads to the terminals specified in your service manual. For the secondary winding, connect one lead to the spark plug wire terminal and the other lead to the coil’s ground terminal.
3. Read the Resistance Value: Observe the resistance value displayed on the multimeter.
4. Compare to the Chart: Compare the measured value to the resistance chart for your specific Stihl model.

Tip 2: Visual Inspection – Don’t Overlook the Obvious

Before you even reach for your multimeter, give the ignition coil a thorough visual inspection. Look for:

• Cracks or Damage: Cracks in the coil body can allow moisture to enter and cause short circuits.
• Burn Marks: Burn marks indicate overheating, which can damage the coil.
• Corrosion: Corrosion on the terminals can interfere with electrical conductivity.
• Loose Connections: Ensure that all wires and connections are secure.

Tip 3: Air Gap Adjustment – The Critical Clearance

The air gap is the small space between the ignition coil and the flywheel. This gap is crucial for generating the spark. If the air gap is too wide or too narrow, the ignition system won’t function correctly.

• Locate the Air Gap: The air gap is typically located on the side of the flywheel, near the ignition coil.
• Use a Feeler Gauge: Use a feeler gauge to measure the air gap. The correct air gap for your Stihl chainsaw model is specified in the service manual. A common range is 0.010 to 0.014 inches (0.25 to 0.35 mm).
• Adjust the Air Gap: If the air gap is incorrect, loosen the mounting screws that hold the ignition coil in place and adjust the coil until the air gap is correct. Then, tighten the mounting screws.

Tip 4: Spark Plug Wire Integrity – A Common Culprit

The spark plug wire connects the ignition coil to the spark plug. A damaged or corroded spark plug wire can prevent the spark from reaching the spark plug.

• Inspect the Wire: Look for cracks, cuts, or damage to the insulation.
• Check the Connections: Ensure that the spark plug wire is securely connected to both the ignition coil and the spark plug.
• Test for Continuity: Use a multimeter to test the spark plug wire for continuity. Set the multimeter to the continuity setting (often indicated by a beep symbol). Connect one lead to each end of the spark plug wire. If the multimeter beeps, the wire has continuity. If it doesn’t beep, the wire is broken and needs to be replaced.

Tip 5: Consider the Module – Not Just the Coil

Some Stihl chainsaws use an ignition module that combines the coil and other electronic components into a single unit. If you suspect a problem with the ignition system, consider testing the entire module, not just the coil. The testing procedure for the module will be outlined in your service manual.

The Cost of Ignition Coil Replacement: A Realistic Budget

Replacing an ignition coil isn’t usually a budget-breaker, but understanding the costs involved is essential for planning your repairs.

Component Costs:

• Aftermarket Ignition Coils: These can range from $15 to $30. Quality can be variable, so read reviews carefully.
• OEM Stihl Ignition Coils: These are generally more expensive, ranging from $30 to $75 or more, depending on the model. While pricier, OEM parts are often more reliable and come with a warranty.

Labor Costs (If Not DIY):

• Professional Repair Shop: Labor rates vary widely depending on your location and the repair shop. Expect to pay anywhere from $50 to $150 per hour. Since replacing an ignition coil is a relatively quick job, labor costs might range from $50 to $100.

Other Potential Costs:

• Spark Plug: It’s always a good idea to replace the spark plug when replacing the ignition coil. Spark plugs typically cost between $5 and $15.
• Service Manual: If you don’t already have one, purchasing a service manual for your specific Stihl model is a worthwhile investment. Service manuals typically cost between $15 and $30.

My Cost-Saving Strategies:

I’ve found that purchasing parts online can often save you money, but be sure to buy from reputable sources to avoid counterfeit or low-quality parts. Additionally, learning to perform basic repairs yourself can save you a significant amount of money in labor costs. There are countless online resources, including videos and forums, that can guide you through the process.

Case Study: Firewood Preparation Budget

Let’s say I’m planning to process 10 cords of firewood this winter. Here’s how I’d factor in potential ignition coil issues into my budget:

• Chainsaw Maintenance: I allocate $50 per year for general chainsaw maintenance, including spark plugs, air filters, and bar oil.
• Potential Ignition Coil Replacement: I set aside an additional $50 as a contingency for a potential ignition coil replacement. This covers the cost of a high-quality aftermarket coil or an OEM coil if necessary.
• Total Chainsaw Budget: $100

This proactive approach allows me to handle unexpected repairs without derailing my firewood preparation budget.

Understanding Timber Prices and Their Impact on Your Project

The cost of timber directly impacts the overall cost of any wood processing or firewood preparation project. Timber prices vary widely depending on several factors, including:

• Wood Species: Hardwoods like oak, maple, and hickory are typically more expensive than softwoods like pine and fir.
• Quality: Clear, knot-free timber is more expensive than timber with defects.
• Location: Timber prices vary depending on the region. Areas with abundant timber resources tend to have lower prices.
• Accessibility: Timber that is easily accessible is less expensive to harvest than timber that is located in remote or difficult-to-reach areas.
• Market Demand: Timber prices fluctuate with market demand.

Global Timber Price Data:

According to recent reports from organizations like the Food and Agriculture Organization of the United Nations (FAO), global timber prices have been volatile in recent years due to factors such as supply chain disruptions, increased demand for wood products, and environmental regulations.

• Softwood Lumber: Prices for softwood lumber have seen significant fluctuations, with prices soaring during the pandemic due to increased demand for home building and renovation projects.
• Hardwood Lumber: Prices for hardwood lumber have been more stable but have also seen increases due to strong demand from furniture manufacturers and other industries.

Regional Timber Price Variations:

Timber prices vary significantly from region to region. For example, timber prices in the Pacific Northwest of the United States, a region with abundant timber resources, are typically lower than timber prices in the Northeast.

• United States: According to the U.S. Forest Service, the average stumpage price (the price paid for standing timber) for sawtimber in the United States in 2022 was around $200 per thousand board feet. However, prices varied widely depending on the species and location.
• Europe: Timber prices in Europe have been increasing due to factors such as increased demand for wood products and stricter environmental regulations. According to the European Commission, the average price for softwood sawlogs in Europe in 2022 was around €80 per cubic meter.
• Asia: Timber prices in Asia have also been increasing due to strong demand from China and other rapidly growing economies. According to the International Tropical Timber Organization (ITTO), the average price for tropical logs in Asia in 2022 was around $300 per cubic meter.

Impact on Firewood Preparation:

Timber prices directly impact the cost of firewood. If you are purchasing logs to process into firewood, the cost of the logs will be a significant factor in your overall budget. If you are harvesting your own timber, you will need to factor in the cost of harvesting, transporting, and processing the timber.

Cost Optimization Strategies:

• Source Timber Locally: Purchasing timber from local sources can often save you money on transportation costs.
• Consider Alternative Species: If you are not particular about the species of wood you use for firewood, consider using less expensive species.
• Harvest Your Own Timber: If you have access to timber resources, harvesting your own timber can save you money. However, be sure to factor in the cost of harvesting, transporting, and processing the timber.
• Buy in Bulk: Purchasing timber in bulk can often save you money.
• Negotiate Prices: Don’t be afraid to negotiate prices with timber suppliers.

Labor Costs: Logging Crew vs. Firewood Handlers

Labor costs are a significant factor in any wood processing or firewood preparation project. The cost of labor will vary depending on several factors, including:

• Skill Level: Skilled loggers and firewood handlers typically command higher wages than unskilled laborers.
• Experience: Experienced workers are typically more productive and efficient, which can offset the higher cost of their wages.
• Location: Labor rates vary depending on the region. Areas with a high cost of living tend to have higher labor rates.
• Demand: Labor rates fluctuate with market demand.

Logging Crew Costs:

Logging crews typically consist of several workers, including:

• Fallers: Fallers are responsible for felling trees.
• Skidders: Skidders are responsible for moving logs from the forest to the landing.
• Loaders: Loaders are responsible for loading logs onto trucks.
• Truck Drivers: Truck drivers are responsible for transporting logs to the mill.

The cost of a logging crew can vary widely depending on the size of the crew, the skill level of the workers, and the location. According to industry estimates, the average cost of a logging crew in the United States is around $50 to $100 per hour.

Firewood Handler Costs:

Firewood handlers are responsible for processing logs into firewood. This typically involves cutting the logs into smaller pieces, splitting the wood, and stacking the firewood.

The cost of firewood handlers can vary depending on the skill level of the workers and the location. According to industry estimates, the average cost of firewood handlers is around $15 to $30 per hour.

Cost Optimization Strategies:

• Hire Skilled Workers: Hiring skilled workers can increase productivity and efficiency, which can offset the higher cost of their wages.
• Invest in Training: Providing training to workers can improve their skills and productivity.
• Use Efficient Equipment: Using efficient equipment can reduce labor costs.
• Automate Tasks: Automating tasks can reduce labor costs.
• Negotiate Wages: Don’t be afraid to negotiate wages with workers.

My Approach to Firewood Labor:

For my own firewood preparation, I mostly rely on sweat equity. However, there are times when I need to hire help, especially for larger jobs. I’ve found that offering a fair wage and providing clear instructions and expectations can attract reliable and hardworking individuals. I also try to make the work as enjoyable as possible by providing refreshments and taking breaks.

Tool Costs: Chainsaws, Splitters, and Maintenance

The cost of tools is another significant factor in any wood processing or firewood preparation project. The cost of tools will vary depending on several factors, including:

• Type of Tool: Chainsaws, splitters, and other specialized tools can be expensive.
• Quality: High-quality tools are typically more expensive than low-quality tools.
• Brand: Some brands are more expensive than others.
• Features: Tools with more features are typically more expensive.
• Condition: New tools are typically more expensive than used tools.

Chainsaw Costs:

Chainsaws are essential tools for any wood processing or firewood preparation project. The cost of a chainsaw can vary widely depending on the size, power, and features of the saw.

• Entry-Level Chainsaws: Entry-level chainsaws typically cost between $150 and $300. These saws are suitable for light-duty tasks such as trimming branches and cutting small trees.
• Mid-Range Chainsaws: Mid-range chainsaws typically cost between $300 and $600. These saws are suitable for a wider range of tasks, including felling small to medium-sized trees and processing firewood.
• Professional Chainsaws: Professional chainsaws typically cost between $600 and $1,500 or more. These saws are designed for heavy-duty use and are suitable for felling large trees and processing large quantities of firewood.

Splitter Costs:

Splitters are used to split logs into smaller pieces for firewood. The cost of a splitter can vary depending on the type of splitter, the splitting force, and the features of the splitter.

• Manual Splitters: Manual splitters are the least expensive type of splitter. These splitters require you to manually swing an axe or maul to split the logs.
• Hydraulic Splitters: Hydraulic splitters are more expensive than manual splitters. These splitters use hydraulic power to split the logs. Hydraulic splitters are available in both gas-powered and electric-powered models.
• Electric Splitters: Electric splitters are often quieter and require less maintenance than gas-powered splitters, but they may not be as powerful.

Maintenance Costs:

In addition to the initial cost of the tools, you also need to factor in the cost of maintenance. Chainsaws and splitters require regular maintenance, such as sharpening the chain, changing the oil, and replacing worn parts.

Cost Optimization Strategies:

• Buy Used Tools: Purchasing used tools can save you money. However, be sure to inspect the tools carefully before you buy them to make sure they are in good working condition.
• Rent Tools: Renting tools can be a cost-effective option if you only need to use them occasionally.
• Maintain Your Tools: Regular maintenance can extend the life of your tools and prevent costly repairs.
• Buy Quality Tools: Investing in high-quality tools can save you money in the long run by reducing the need for repairs and replacements.

My Tool Investment Philosophy:

I believe in investing in quality tools that will last. While it’s tempting to save money by buying cheaper tools, I’ve found that they often break down more frequently and require more maintenance. A well-maintained, high-quality chainsaw or splitter can last for many years and save you money in the long run.

Drying Time Estimation Based on Moisture Content

Drying firewood is a crucial step in preparing it for burning. Properly dried firewood burns more efficiently, produces more heat, and creates less smoke and creosote buildup in your chimney. The drying time for firewood depends on several factors, including:

• Wood Species: Hardwoods like oak and maple take longer to dry than softwoods like pine and fir.
• Climate: Warm, dry climates are ideal for drying firewood.
• Stacking Method: Proper stacking methods can improve airflow and speed up the drying process.
• Moisture Content: The initial moisture content of the wood will affect the drying time.

Estimating Drying Time:

There is no exact formula for calculating drying time, but here’s a general guideline:

1. Measure Moisture Content: Use a moisture meter to measure the moisture content of the wood. Firewood should ideally have a moisture content of 20% or less before burning.
2. Consider Wood Species: Hardwoods typically take 6-12 months to dry, while softwoods typically take 3-6 months.
3. Factor in Climate: In warm, dry climates, firewood can dry more quickly. In humid climates, it can take longer.
4. Stacking Method: Stack the firewood in a single row, off the ground, with good airflow.
5. Monitor Moisture Content: Check the moisture content of the wood periodically to monitor the drying process.

General Drying Time Estimates:

• Softwoods (Pine, Fir): 3-6 months in a dry climate, 6-12 months in a humid climate.
• Hardwoods (Oak, Maple): 6-12 months in a dry climate, 12-24 months in a humid climate.

My Drying Process:

I always cut and split my firewood in the spring, giving it ample time to dry throughout the summer. I stack the wood in a single row, off the ground, with plenty of space between the rows for airflow. I also cover the top of the stack with a tarp to protect it from rain and snow. I use a moisture meter to check the moisture content of the wood before burning it.

Actionable Takeaways and Next Steps

Diagnosing and addressing ignition coil issues in your Stihl chainsaw doesn’t have to be a daunting task. By understanding the resistance chart, following the essential testing tips, and budgeting realistically for potential replacements, you can keep your saw running smoothly and efficiently.

Here are some actionable takeaways:

• Consult Your Service Manual: Always refer to the service manual for your specific Stihl chainsaw model for accurate resistance values and testing procedures.
• Invest in a Multimeter: A multimeter is an essential tool for diagnosing electrical problems.
• Perform Visual Inspections: Don’t overlook the obvious – check for cracks, damage, and corrosion.
• Adjust the Air Gap: The air gap is crucial for generating the spark.
• Consider the Spark Plug Wire: A damaged spark plug wire can prevent the spark from reaching the spark plug.
• Budget Realistically: Factor in the cost of potential ignition coil replacements into your wood processing or firewood preparation budget.
• Learn to DIY: Learning to perform basic repairs yourself can save you a significant amount of money.

Next Steps:

1. Gather Your Tools: Collect the necessary tools, including a multimeter, feeler gauge, and screwdrivers.
2. Locate Your Service Manual: Find the service manual for your specific Stihl chainsaw model.
3. Inspect Your Ignition Coil: Perform a visual inspection of the ignition coil.
4. Test the Ignition Coil: Use a multimeter to test the resistance of the primary and secondary windings.
5. Adjust the Air Gap: Check and adjust the air gap.
6. Replace the Ignition Coil (If Necessary): If the ignition coil is faulty, replace it with a new one.

By following these steps, you can ensure that your Stihl chainsaw is running at its best and that you are prepared for any wood processing or firewood preparation project. Remember to always prioritize safety and consult a qualified technician if you are unsure about any repair procedure. With a little knowledge and effort, you can keep your chainsaw running strong for years to come.

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