How to Determine the Quality of Spark Plugs?
2 Answers
Methods to distinguish the quality of spark plugs: 1. Color identification: A well-functioning spark plug appears dark red; a white color indicates a lean air-fuel mixture, while a black color indicates a rich mixture. 2. Observe the spark using the ignition wire: A good spark plug produces a blue spark, forming a nearly straight line between the electrodes. A faulty spark plug may show no spark or erratic sparks. 3. Spark color: A very strong spark appears white, while a weak spark appears red—such spark plugs are generally faulty. The function of a spark plug is to introduce the high-voltage pulse generated by the ignition coil into the combustion chamber, using the spark produced between the electrodes to ignite the air-fuel mixture and complete combustion. Common types of spark plugs include resistor spark plugs, platinum spark plugs, and iridium spark plugs.
Hey, as someone who often works on cars myself, checking spark plugs is actually quite simple! My favorite method is removing them for visual inspection: if the electrodes are severely worn or the gap is too wide, it weakens ignition and affects engine performance. Using an inexpensive gap gauge, the normal range is usually between 0.7 to 1.0mm – anything beyond that requires adjustment. Then check the color: a healthy plug should be light brown; if it's blackened, it indicates oil contamination or a too-rich fuel mixture; white electrodes suggest overheating, possibly from cooling system issues. Heavy carbon buildup can be cleaned off, but frequent buildup may point to engine oil leaks or poor fuel quality. Regular inspections prevent ignition failures and save repair costs. Spark plugs typically last 20,000-30,000 km – timely replacement ensures stable power and fuel efficiency.
