汽油品質差導致發動機故障燈亮 (發動機失火故障排除)——Low quality petrol causing engine fault light (engine misfire troubleshooting)

電控發動機具有製造精度高、系統控制複雜等特點，即便一些並不起眼的因素干擾，也可能造成發動機部件受損，或是發出故障警報。下面，我們就來講述一例因加油引起的發動機故障.

汽油品質差導致發動機故障燈亮故障現象及診斷

車主反映儀錶板點亮發動機故障警告燈，發動機意速抖動維修人員連接診斷儀檢測，顯示第三缸失火。將第二缸和第三缸的火花塞、點火線圈對調，第二缸失火始終存在，第二缸點火始終正常，因此排除點火線圈和火花塞故障的可能性。此外，拆下的第三缸火花塞端部有濕潤的燃油殘留，初步判斷第三缸噴油器會噴油。測量第三缸缸壓為4Bar，明顯低於標準的12 Bar，這應該是發動機失火的原因。

故障排除及分析（案例）

氣缸失去氣密性，主要原因有氣缸墊損傷、氣門損傷、活塞環損傷，以及氣缸壁損傷等。拆解發動機檢查，看到第三缸的氣門邊緣出現崩裂損傷。同時，可以看到各氣缸內均有較多積炭。

車主在描述故障時提到，前一天剛給車加過油，故障是在加完油行駛了約40km之後出現的。維修人員考慮到即便是加注了品質較差的燃油，也通常只是造成缸內積炭增加，不至於使氣門損傷。進一步詢問得知，在加油時還使用了燃油添加劑

由於一些燃油添加劑具有強力的清洗作用，混有這些清洗成分的燃油進入缸內，可能使附著在氣缸壁上的積炭產生鬆動，甚至出現較大體積的積炭剝落。這些積炭碎塊在發動機振動的作用下飛濺起來，如果剛好卡在處於打開狀態的氣門的背面，當氣門再次關閉時，堅硬的碎塊就損傷氣門的邊緣，致使氣缸失去氣密性

維修人員清理了發動機缸內積炭，更換損傷的氣門，並且更換當前油箱內的燃油。考慮到進入氣缸內的燃油和空氣純淨度不足，會引起缸內出現較多積炭，因此同時更換了燃油濾清器和空氣濾清器交車時，還提醒車主應前往油品有保障的正規加油站添加燃油，不要隨便使用燃油添加劑。

車輛加注燃油之後出現發動機報警的情況並不罕見，通常都是因燃油品質不佳引起。也有像本文提到的這種故障情況，因隨意使用添加劑使缸內積炭剝落，造成發動機部件損傷，影響運轉。我們在日常用車時，應注意對進氣、供油系統的維護，保持進入氣缸內參與燃燒的空氣和燃油足夠潔淨，減少缸內積炭的形成。

——————————————————————————————————————

Electronically controlled engines are characterised by high manufacturing precision and complex system control. Even some insignificant disturbances can cause damage to engine components or give a fault alarm. The following is an example of an engine failure caused by refuelling.

Poor petrol quality causes engine fault light and diagnosis

The owner reported that the dashboard lit up with the engine fault warning light and the engine was shaking at speed. The second and third cylinder spark plugs and ignition coils were adjusted, the second cylinder misfire always existed, the second cylinder ignition was always normal, so the possibility of faulty ignition coils and spark plugs was ruled out. In addition, there was wet fuel residue on the end of the spark plug of the third cylinder, so the initial judgment was that the third cylinder injector would spray fuel. The cylinder pressure of the third cylinder was measured at 4 Bar, which was obviously lower than the standard 12 Bar, and this should be the cause of the engine misfire.

Troubleshooting and Analysis (Case)

The main causes of cylinder loss of air tightness are cylinder gasket damage, valve damage, piston ring damage, and cylinder wall damage. Dismantle the engine to check, see the third cylinder valve edge cracking damage. There was also a large amount of carbon build up in each cylinder.

When describing the fault, the owner mentioned that the car had just been refuelled the day before and the fault had occurred after a drive of approximately 40km. The mechanic considered that even if the car had been filled with poor quality fuel, it would normally only cause an increase in carbon build-up in the cylinders and not valve damage. Further enquiries revealed that fuel additives were also used during refuelling.

As some fuel additives have a strong cleaning effect, fuel mixed with these cleaning ingredients may cause the carbon to loosen on the cylinder walls and may even cause a large amount of carbon to flake off. If these pieces of carbon splash up under the vibration of the engine and get stuck on the back of the open valve, when the valve is closed again, the hard pieces will damage the edges of the valve and cause the cylinder to lose its airtightness.

The mechanic cleaned the engine cylinder of carbon, replaced the damaged valve and replaced the current fuel in the tank. The fuel filter and air filter were also replaced and the vehicle was delivered with a reminder that fuel should be refilled at a proper fuel station with guaranteed fuel quality, rather than using fuel additives.

It is not uncommon for a vehicle to have an engine alarm after refuelling, usually due to poor fuel quality. There are also cases like the one mentioned in this article, where the use of additives has caused carbon to peel off from the cylinder, resulting in damage to engine components and affecting operation. We should pay attention to the maintenance of the air intake and fuel supply system in our daily use, so that the air and fuel entering the cylinders are clean enough to reduce the formation of carbon in the cylinders.