What Causes a National IV Diesel Vehicle to Emit Black Smoke?
3 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.
I often deal with this issue during car repairs. For National IV diesel vehicles emitting black smoke, it's mostly related to air supply or the fuel system. First, check if the air filter is clogged—replace it if it's dirty. Then inspect the fuel injectors for blockages; you can clean them with a cleaning agent. If the turbocharger is faulty, such as stuck blades or air leaks, inadequate air intake will cause excessive smoke. Unstable ECU control can also cause issues, like faulty oxygen sensors misleading fuel injection quantities. Additionally, poor fuel quality with too many impurities leads to incomplete combustion. I've encountered many owners whose cars started smoking after refueling themselves, but switching to standard diesel solved the problem. Get it checked at a professional shop promptly to avoid engine damage. Regular maintenance of filters and the fuel system can help prevent this.
