There is a hot topic about cars these days. A Mercedes Benz owner went to the 4S store for daily maintenance and replaced the spark plug after 20000 kilometers,

首先來說，奔馳在本土地區(qū)通常都是8萬公里更換火花塞，根據(jù)國內(nèi)油品改成6萬公里更換，可是在部分地區(qū)由于油品質(zhì)量問題發(fā)動機產(chǎn)生爆震高溫，4萬公里左右時火花塞負(fù)極就會被燒化，燒灼產(chǎn)生的碎渣極有可能掉進(jìn)活塞缸壁之間，從而造成拉缸損壞發(fā)動機。

First of all, Mercedes Benz usually replaces the spark plug at 80000 km in the local area, which is changed to 60000 km according to the domestic oil products. However, in some areas, due to the oil quality problem, the engine produces knock and high temperature, and the negative electrode of the spark plug will be burned at about 40000 km, and the slag produced by burning is likely to fall between the piston cylinder wall, resulting in cylinder pulling and engine damage.

有一種說法是，發(fā)動機通常享受三年或10萬公里質(zhì)保，如果在4萬公里時發(fā)動機損壞勢必會對廠家造成很大利益損失，口碑、投訴也會受到不利影響，所以保養(yǎng)手冊與海外版不同，采取2萬公里更換火花塞的辦法。

There is a saying that the engine usually enjoys a three-year or 100000 km warranty. If the engine is damaged at 40000 km, it is bound to cause great loss of interests to the manufacturer, and the reputation and complaints will also be adversely affected. Therefore, unlike the overseas version, the maintenance manual adopts the method of replacing the spark plug at 20000 km.

單憑油品說事顯然有甩鍋嫌疑，眾所周知，火花塞根據(jù)極點材料不同、等級不同，其使用壽命也會不同。按從低到高劃分分別是：鎳合金、鉑金、銥金、依鉑金、雙銥金（針對針）、釕合金火花塞。奔馳原廠采用鉑金和銥金材料的火花塞，通常使用壽命在5~8萬公里之間，由于油品不好造成火花塞出現(xiàn)沉積、電極消耗、MMT污損、熏黑、燒灼等現(xiàn)象，出現(xiàn)問題的火花塞部分仍可以繼續(xù)點火工作，但是點火原本的電擊點會發(fā)生位移！影響火焰燃燒。

Oil alone is obviously suspected of throwing the pot. As we all know, the service life of spark plugs will be different according to different pole materials and grades. From low to high, they are: nickel alloy, platinum, iridium, platinum, double iridium (for needle), ruthenium alloy spark plug. The spark plugs made of platinum and iridium in Mercedes Benz's original factory usually have a service life of 50000 ~ 80000 kilometers. Due to poor oil products, the spark plugs appear deposition, electrode consumption, MMT fouling, blackening, burning and other phenomena. The spark plugs with problems can still continue to ignite, but the original electric shock point of ignition will be displaced! Affect flame combustion.

除了油品外為何奔馳發(fā)動機需要2萬公里更換火花塞呢？這就要提到奔馳發(fā)動機的第三代汽油缸內(nèi)直噴技術(shù)了。奔馳第三代汽油缸內(nèi)直噴技術(shù)名為BlueDIRECT缸內(nèi)直噴技術(shù)，通常缸內(nèi)直噴是靠高壓油泵+多次噴油構(gòu)成，但是奔馳這套可沒有這么簡單，在一個沖程內(nèi)更多可實現(xiàn)5次燃油噴射（馬自達(dá)SKYACTIV-G為三次噴射，一般為兩次噴射），ECU給出指令控制火花塞在1毫秒時間內(nèi)需點火4次，也就是4次火花釋放（稀薄燃燒技術(shù)）。配合缸內(nèi)渦流設(shè)計讓混合氣達(dá)到燃效效果，同時也能滿足苛刻的排放法規(guī)。

In addition to oil, why does Mercedes Benz engine need to replace spark plugs for 20000 kilometers? This is about to mention the third generation gasoline direct injection technology of Mercedes Benz engine. Mercedes Benz's third-generation gasoline in cylinder direct injection technology is called bluedirect in cylinder direct injection technology. Generally, the in cylinder direct injection is composed of high-pressure oil pump and multiple fuel injections, but Mercedes Benz is not so simple. It can achieve up to five fuel injections in one stroke (Mazda skyactiv-g has three injections, usually two injections), ECU gives a command to control the spark plug to ignite 4 times within 1 millisecond, that is, 4 spark releases (lean combustion technology). With the swirl design in the cylinder, the mixture can achieve the best combustion effect and meet the stringent emission regulations.

由于點火次數(shù)的增加帶有缸內(nèi)直噴技術(shù)的發(fā)動機會縮短火花塞使用壽命，奔馳BlueDIRECT在做功沖程需點火四次也就是進(jìn)一步縮短了火花塞壽命，再加燃油油品問題，所以奔馳發(fā)動機每2萬公里更換火花塞也就不足為奇了。

Due to the increase of ignition times, engines with in cylinder direct injection technology will shorten the service life of spark plugs. Mercedes Benz bluedirect needs to ignite four times in the power stroke, which further shortens the service life of spark plugs. In addition, it is not surprising that Mercedes Benz engines replace spark plugs every 20000 kilometers.