How to Determine Which Ignition Wire is Damaged?
2 Answers
Methods to determine ignition wire damage are as follows: 1. Set the multimeter to the 20 kilo-ohm range and touch the two metal ends with the probes. The normal reading should be between a few ohms to several dozen ohms. 2. The resistance of automotive ignition wires is generally in the range of several kilo-ohms. When measuring the resistance of automotive ignition wires with a multimeter, typically select the 20 kilo-ohm range. Connect the red and black probes of the multimeter to both ends of the ignition wire. If the multimeter displays a reading between 1 and 20 kilo-ohms, it indicates that the ignition wire is not broken. 3. Do not directly measure the spark, as the ignition coil output voltage is very high and can damage the digital meter. To check the spark, remove the spark plug and ground it to the engine casing to observe the spark plug discharge gap for any discharge sparks, as well as the color and intensity of the spark, to roughly determine if it is normal.
I've been driving for over a decade and have encountered quite a few ignition wire failures. Initially, you'll notice the engine shaking violently, especially at idle when the car becomes noticeably unstable, with insufficient power making hill climbing difficult. A simple method is to carefully pull the ignition wire off the spark plug end with a screwdriver after starting the engine. If removing a particular wire doesn't significantly change the engine sound or cause RPM to drop, that wire is definitely faulty; if the engine shakes more violently or stalls immediately upon removal, it means the good wire is still functioning. Surface inspection is also crucial - cracks, burn marks, or excessive softness in the wire indicate aging. Don't rely solely on touch; using a multimeter to measure resistance is most accurate. The normal value should be around several dozen ohms per centimeter - replace immediately if readings deviate significantly. Regular maintenance should include checking ignition wires, especially for older vehicles or those frequently driven on muddy roads. Replacing with quality wires brings peace of mind. Always wear insulated gloves for safety before working.
