What are the symptoms of a failing ignition coil?
A failing ignition coil can cause a range of noticeable symptoms in a vehicle. The ignition coil is a critical component in the vehicle's ignition system, responsible for providing the high-voltage spark that ignites the air-fuel mixture in the engine's cylinders. When the ignition coil starts to fail, it can lead to various performance issues and problems.
Common Symptoms of a Failing Ignition Coil
- Rough Idling or Stalling: A failing ignition coil can cause the engine to run rough, misfire, or even stall, especially at idle or low speeds.
- Reduced Engine Power and Performance: As the ignition coil weakens, it may not be able to provide the necessary spark intensity, leading to a loss of power and reduced engine performance.
- Check Engine Light Illumination: The vehicle's onboard diagnostic system will typically detect issues with the ignition coil and trigger the check engine light on the dashboard.
- Difficulty Starting the Engine: A faulty ignition coil can make it difficult to start the engine, especially when the engine is cold.
- Decreased Fuel Efficiency: Misfiring caused by a failing ignition coil can lead to increased fuel consumption and reduced fuel efficiency.
It's important to address any issues with the ignition coil promptly, as a failing coil can cause further damage to other components in the ignition system or the engine itself if left unrepaired.
How to tell if a coil needs replacing?
You can tell a coil needs replacing by observing symptoms like a check engine light, rough engine operation (sputtering, shaking, backfiring), and stalling or difficulty starting. For vapes, a coil needs replacing when there is a weak or burnt flavor, the device gurgles or leaks, or the e-liquid color changes.
For vehicle ignition coils
- Illuminated check engine light: The light will often come on to indicate a problem, which could be a coil-related misfire.
- Engine misfires: You may feel or hear the engine sputtering, shaking, or having a "coughing" sound, especially at idle.
- Difficulty starting: The engine may struggle to start, or take longer to crank.
- Stalling: The engine can stall while driving or when stopped, such as at a traffic light.
- Reduced power: The vehicle may feel sluggish, with poor acceleration and reduced power.
- Poor fuel economy: A failing coil can lead to decreased gas mileage.
- Backfiring: Unburned fuel can exit the exhaust, causing a loud "bang".
For vape coils
- Weak or burnt flavor: The taste will diminish and become less consistent, or develop a burnt taste.
- Gurgling sounds: Excess e-liquid can flood the chamber and cause a gurgling noise when you take a puff.
- Leaking: E-liquid may leak from the tank or pod, often from the center of the coil.
- Flashing light: Many devices will flash or display an "atomiser error" message when there is a coil issue.
- Reduced vapor production: You may notice less vapor is produced with each puff.
- E-liquid color change: The color of the e-liquid in the tank may change or darken.
Can you drive with a bad ignition coil?
You should not drive with a bad ignition coil, as it can cause serious engine damage and is unsafe. While it may seem possible to drive short distances, doing so can lead to expensive problems like a damaged catalytic converter from unburnt fuel, increased wear on other engine components, and potentially a sudden breakdown. The best course of action is to get the ignition coil replaced as soon as possible.
Risks of driving with a bad ignition coil
- Damage to the catalytic converter: Unburnt fuel can enter the exhaust system and ignite in the hot catalytic converter, destroying it and leading to a costly repair.
- Engine damage: Unburnt fuel can wash oil off the cylinder walls, which can cause wear and damage to pistons, cylinder walls, and bearings over time.
- Poor performance: The car will likely run poorly, with symptoms like misfires, a rough idle, stalling, poor fuel economy, and a lack of power.
- Increased strain on other parts: A failing coil can put extra strain on spark plugs, the engine control unit (ECU), and the crankshaft, potentially leading to more expensive repairs.
- Safety hazard: The car's performance issues can be dangerous, especially when driving in traffic or on the highway, and it could break down unexpectedly.
How often should you replace ignition coils?
around every 60,000 to 100,000 miles
So, when should you replace the ignition coils? If your machines are experiencing any of the symptoms above, it might be time to replace your coils. Otherwise, as a general guideline you should inspect and potentially replace your coils around every 60,000 to 100,000 miles or every 5 years.
How do you tell if your ignition coil is bad?
A bad ignition coil can be identified by a check engine light and symptoms like rough idling, engine misfires, poor acceleration, and difficulty starting the engine. Other signs include stalling, backfiring, decreased fuel economy, and a strong smell of gasoline.
Common symptoms
- Check Engine Light: The onboard computer will often detect ignition problems and illuminate the check engine light. A mechanic can use an OBD2 scanner to retrieve misfire codes, such as P0302, to pinpoint the specific cylinder.
- Engine misfires: You may notice the engine sputtering, shaking, or jerking, especially when accelerating.
- Rough idle: The engine may feel shaky or vibrate noticeably while the vehicle is idling.
- Poor acceleration: The vehicle may feel sluggish or hesitate when you press the gas pedal.
- Difficulty starting: The engine may crank for a longer time than usual before starting, or it may not start at all.
- Stalling: The engine may stall while driving or when stopped at a light.
- Backfiring: A sudden loud bang from the exhaust can occur when unburned fuel ignites.
- Reduced fuel economy: Incomplete combustion due to a weak spark means more fuel is wasted, leading to lower miles per gallon.
- Smell of gasoline: Unburned fuel can exit the exhaust, creating a strong gas smell.
How to test further (requires caution)
- Use an OBD2 scanner: This can help identify specific misfire codes that point to a faulty cylinder, as seen in this YouTube video.
- Swap ignition coils: A simple test is to swap the coil from the suspected bad cylinder with a known good cylinder. If the misfire code follows the coil to the new cylinder, then the coil is likely bad, notes this YouTube video.
- Check resistance (for advanced users): A multimeter can be used to measure the resistance of the coil windings. A well-functioning coil will have a specific resistance range, but this requires a repair manual for correct specifications and extreme caution due to high voltage.
