How does spark plug gap affect engine ignition?

Spark plug gap is a key parameter that affects the ignition efficiency of the engine. Its size directly affects the intensity and stability of the spark and the combustion effect of the mixture.

1. Too small a gap: Insufficient spark energy
Weak spark: Too small a gap will cause the spark energy to be concentrated but short-lasting, and the mixture cannot be fully ignited, especially under low temperature or lean combustion conditions, which is prone to ignition failure.
Risk of carbon deposits: Weak sparks may cause incomplete combustion of the fuel, and residues may accumulate on the electrode surface, further narrowing the gap and forming a vicious cycle.
Applicable scenarios: Old low-compression ratio engines or carburetors may use smaller gaps, but modern electronic fuel injection engines usually require larger gaps.

2. Too large a gap: Insufficient ignition voltage
Risk of misfire: When the gap is too large, the ignition coil may not be able to generate enough high voltage electricity to break through the gap, resulting in missing sparks.
Increasing coil load: Forcing the ignition system to work continuously at maximum voltage may shorten the life of the ignition coil.
Example: Turbocharged or high-compression ratio engines require a wider gap to match the high-energy ignition system, but it will still fail if it exceeds the design value.

3. Ideal gap: balance performance and reliability

Optimal combustion efficiency: The appropriate gap can produce a sufficiently long and strong spark to ensure that the mixture is fully burned.

Increase power and fuel consumption: Complete combustion can reduce knocking and emissions, while improving torque and fuel economy.

Dynamic adaptability: Wide gaps dissipate heat better under high loads, but need to be matched with a strong ignition system.