Can an ignition coil fail when hot?
A damaged coil can short some windings, causing high current but low inductance, so low energy. As it gets hot the energy falloff weakens the spark until the engine quits making noises. Electronically switched circuits fail like this because the silicon stops switching around 100 C.
What causes weak ignition spark?
Common reasons for weak spark are faulty flywheel magnets and faulty stator. Loss of spark is caused by anything that prevents coil voltage from jumping the electrode gap at the end of the spark plug. This includes worn, fouled or damaged spark plugs, bad plug wires or a cracked distributor cap.
How can you tell if an ignition coil is weak?
Signs of a Bad Ignition Coil
- Illuminated Check Engine Light. With most modern vehicles, a faulty ignition coil is enough to turn on the Check Engine Light.
- Misfiring Engine. If an ignition coil is not working properly, your engine will likely misfire.
- Hard Starts.
- Worsening Gas Mileage.
- Diminished Power.
- Sudden Backfires.
What do you need to know about ignition coil failure?
Check your high tension leads (HT Leads). They run between the distributor and spark plugs. Ignition coil failures result in 1 or more spark plugs not receiving the appropriate amount of charge. If you have trouble starting your vehicle in the cold, this is a good sign of potential ignition coil failure.
How much does it cost to replace an ignition coil?
If you have the replacement professionally done then the labor costs will be between $50 and $100 per hour. Therefore, you can expect to pay at least $150 to $200 if you were to take your car to an automotive repair shop and have them replace your ignition coil for you. If you choose to go to a dealership, expect to pay even more.
How can I tell if my ignition coil is backfiring?
The backfiring problem can usually be detected by the emission of a black smoke through the exhaust pipe. The smell of gasoline in that smoke may also give away the ignition coil failure. Another sign of a faulty ignition coil is poor fuel economy.
What should the resistance of a furnace ignitor be?
Disconnect the hot surface ignitor from the control board and measure the resistance. A good hot surface ignitor will have a resistance of 40 to 90 ohms. Greater than 90 ohms indicates a failing or failed hot surface ignitor. We have two YouTube videos below that show hot to test and troubleshoot furnace ignitor problems.