What Causes a National IV Diesel Vehicle to Emit Black Smoke?
2 Answers
National IV diesel vehicles emit black smoke due to insufficient compression pressure and oil burning caused by wear of valves, piston rings, and cylinder liners. This alters the normal mixture ratio of the air-fuel mixture at the end of the compression stroke, leading to fuel combustion under oxygen-deficient conditions. The combustion process tends to produce carbon deposits, and the exhaust gases form large amounts of black smoke. The following are related explanations: 1. Overly rich fuel mixture: Black smoke, also known as carbon smoke, is mainly caused by an overly rich fuel mixture, poor formation of the combustible mixture, or incomplete combustion in diesel engines. 2. Tiny solid particles: Under high-temperature and high-pressure combustion conditions in diesel engines, localized oxygen deficiency leads to cracking and dehydrogenation, forming tiny solid particles mainly composed of carbon. This is a manifestation of incomplete fuel combustion in the combustion chamber.
I often encounter black smoke from China IV diesel vehicles, mainly due to incomplete combustion. For example, clogged or aged fuel injectors can cause uneven diesel spray, leading to incomplete burning and black smoke. If the air filter is blocked, insufficient air intake will also result in incomplete combustion. I've seen many vehicles with turbocharger carbon buildup or damage, leading to insufficient compression and increased smoke. Additionally, issues with the ECU control unit, such as incorrect sensor signals, can cause improper fuel injection timing. Moreover, using low-quality diesel or fuel mixed with impurities can lead to severe smoke as the impurities don't burn cleanly. I recommend checking these areas first. Ignoring them can lead to increased engine wear, reduced power, and higher repair costs over time. It's best to regularly clean the fuel injection system and use standard-compliant diesel for prevention.
