Big gap is good?
Since the big clearance changes the performance of the engine so much, it is time to increase the clearance. This, really can’t!
Each model has a corresponding matching ignition system, and the relevant parameters are matched to the corresponding design, especially the maximum voltage that the ignition coil (high voltage pack) can provide, that is, the maximum breakdown voltage that the ignition coil provides to the spark plug is certain. As shown below, the breakdown voltage of the spark plug increases with the increase of the gap, and after exceeding the maximum voltage provided by the ignition coil, it will be on fire, no breakdown discharge, and no combustion. When the car is designed and manufactured, the designer will leave a certain redundancy space between the maximum voltage provided by the ignition coil and the breakdown voltage required by the spark plug.
Spark plug is a consumable, many owners do not know the regular replacement, especially the original car is a nickel alloy spark plug model, there are individual owners do not change the spark plug, and with the loss of the spark plug, the gap is getting larger and larger, the breakdown voltage is getting higher and higher, the fire rate is getting higher and higher.
Take a look at the spark plug in the use of loss process, ignition conditions have changed?
Initially, the actual breakdown voltage required by the spark plug is always less than the maximum voltage actually provided by the ignition coil, including idle, rapid acceleration or large load, it is completely fine.
As the speed increases, the ignition coil heating temperature increases, the coil charging may not be enough, and the working efficiency is slightly reduced, resulting in a slight decrease in the maximum supply voltage as the speed increases. When idling and starting the vehicle, the spark plug electrode temperature is low, the electrons are not easy to emit, the mixture is not easy to impact ionization, and with the increase of the speed, the temperature of the spark plug electrode is increased, the electrons are easy to emit, the mixture is easy to impact ionization, resulting in the breakdown voltage of the spark plug with the increase of the speed and the decrease. ③ Acceleration, rapid acceleration or large load, the intake becomes more, the injection becomes thicker, the temperature of the spark plug electrode decreases, and the density of the mixture increases, resulting in a significant increase in the breakdown voltage of the spark plug, as shown in the red sharp corner above.
With the use, the spark plug is damaged by electrical spark and oxidation corrosion under high temperature and high pressure, the spark plug gap becomes larger, in rapid acceleration or large load, the actual breakdown voltage required by the spark plug exceeds the maximum voltage that the ignition coil can actually provide, at this time the spark plug fire cylinder, and accompanied by engine jitter and other symptoms.
If the owner still does not know to replace the spark plug, as the spark plug continues to wear, the spark plug gap becomes larger, in the start of the vehicle, idle, rapid acceleration or large load, the actual need for the spark plug breakdown voltage exceeds the ignition coil can actually provide the maximum voltage, at this time the spark plug fire cylinder, and accompanied by engine jitter, idle instability, speed instability and other symptoms, Even at the time of medium load and high speed, the vehicle speed is slow, the speed does not go up, and the symptoms such as lack of cylinder. In addition, if the vehicle is a turbocharged engine at this time, after the so-called “turbo intervention”, there will be more spark plug fire and cylinder loss due to excessive clearance, and accompanied by engine shake symptoms.
Finally, the owner could not bear it, went to the auto repair shop, found the problem, and replaced the spark plug.
When the gap is too large, the ignition coil due to multiple fires, the energy can not be normally consumed through the spark plug discharge, the ignition coil heat is abnormally large and the probability of coil high voltage breakdown is larger, and the spark plug is also at risk of breakdown because it exceeds its normal insulation high voltage value.
