Spark plugs also have a life span, depending on the use of different conditions, the replacement interval also varies greatly.
The normal condition of the spark plug to the late use, the most obvious feeling is not good to start the car, is to be able to start the car also need 5 ~ 6 seconds. This is because the spark plug electrode consumption is too much, the center of the electrode around are rounded by the electric spark. You can see the following picture.
We all know the principle of tip discharge, the electric spark is most likely to be released from the tip of the electrode. In this case, the electric spark will be very weak and runoff, and also unstable. In addition, the spark plug gap is too large will also lead to ignition strength is not enough, can not penetrate the electrode gap gas discharge to ignite the gas mixture.
To determine whether the spark plugs should be changed, the most intuitive feeling is the increase in fuel consumption, a hundred kilometers will even increase one to two oil. This time you will feel the pain, the exhaust pipe is not exhaust gas, it is money ah.
Some cars show a decline in climbing ability, especially when accelerating sharply feel the car's power becomes meat, with no burst of force. This situation is mostly because the spark plug ignition effect becomes worse misfire rate increases, the mixture is not fully burned or even not burned on the discharge, can not play power.
All of these are spark plugs in the normal use of the phenomenon, these conditions indicate that the design life of the spark plug has reached, and needs to retire.
If it is not the normal use of the situation? Let's also sort it out by experience.
Cold cars start normal, hot cars start difficult, this is because the spark plug long-term use, the resistance value has changed, the main performance is the normal driving often feel the throttle in a section suddenly do not feel the role of the engine will pause for a while and then return to normal. Some cars will appear in the driving stutter, and there is no regular, which is generally caused by the spark plug fire, because the spark plug has a breakdown part, resulting in high voltage leakage, there is no spark occasionally. There are cars, cold start difficulty, after starting idle speed is unstable, high and low, the exhaust gas has a pungent gasoline smell, fuel consumption increases, idle speed after warming up back to normal, which is likely to be spark plug carbon build-up.
Some cars have engine shaking, noise, and can even hear the sound of knocking cylinder, which is likely to spark plug center electrode ceramic body is broken, this situation will cause the engine to burst, spark plug appearance may not change, encounter this situation is a word: change. The throttle is not sensitive to slow response, especially when driving at high speed or rapid acceleration, feel a big difference from the previous, most of them are caused by the spark plug insulator leakage, there may also be too much carbon caused by the bypass discharge, must be replaced.
These are some typical cases of sorting out, encounter this situation, you can first consider this aspect because changing the spark plug is a routine operation, the general owners can solve. Only when the problem remains after replacing the new spark plug, only to indicate that the fault is caused by other parts. If beyond the owner's knowledge, or hurry to find a professional mechanic to troubleshoot the problem.