How to Determine the Quality of Spark Plugs?

[DelJanelle]

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.

[SanRebecca]

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.

[JeffreyLee]

From years of auto repair experience, spark plug condition directly reflects engine health. After removing a spark plug, my first check is electrode wear: replace if the sharp edges are rounded, otherwise uneven ignition occurs. Next, inspect electrode gap using a specialized tool - refer to the vehicle manual for standard values. Color analysis is revealing: tan is good; black often indicates oil contamination or incomplete combustion; whitish color suggests overheating, possibly from low coolant or turbo system issues. Heavy carbon buildup requires cleaning or replacement. Gap problems frequently cause hard starting or power loss. Always correlate with engine symptoms like rough idling. Regular maintenance extends engine lifespan.

[SarahLynn]

The key to judging spark plug condition lies in three points: First, inspect the appearance – severely worn electrodes make ignition difficult; then measure the gap (around 0.8mm is acceptable); finally check the color. Light brown is normal; black indicates oil contamination; white suggests overheating. It's easy to remove them yourself to identify issues. Clean promptly when excessive carbon buildup occurs. If your car starts sluggishly or lacks acceleration power, spark plugs are often the culprit. Recommended inspection every 15,000km to avoid major repair troubles.

[JoannaAnn]

When learning to inspect spark plugs, I focus on details: the electrodes must show no signs of erosion, and the gap needs to be precise—measured with a feeler gauge for standard clearance. Color is key: light brown indicates health; pitch black may suggest oil mixture issues; pure white reveals overheating, requiring cooling system checks. Carbon buildup affects ignition efficiency—clean or replace as needed. Combine this with engine performance, like rough idling, to confirm spark plug issues. This method is beginner-friendly and helps save on repair costs. Regular inspections are essential.