Why is a urea-fueled vehicle emitting black smoke?

[DelLucy]

Incomplete combustion of fuel injected into the cylinder. When there is insufficient air intake in the cylinder, it can easily lead to high temperature and oxygen deficiency in the combustion chamber. The unburned carbon molecules in the fuel aggregate to form free particles, which are suspended in the combustion gas and expelled with the exhaust, resulting in black smoke. Additionally, thick blue smoke may appear from the exhaust pipe when the vehicle starts, indicating oil burning. Here are the details: 1. Oil burning phenomenon: Oil burning refers to engine oil entering the engine and burning together with the fuel mixture, which can cause rapid damage to the vehicle's oxygen sensor, increase carbon deposits in the combustion chamber, raise fuel consumption, and in severe cases, lead to irreparable engine damage. 2. Detection method: To detect oil burning, fill the vehicle with engine oil, drive 1000 kilometers, and then weigh the oil filter. Repeat this process several times. If the oil consumption exceeds 0.3 liters per 1000 kilometers, it indicates an oil burning phenomenon.

[DeAiden]

Having driven for many years, I've encountered diesel vehicles emitting black smoke several times, mainly due to incomplete combustion. The most common cause is issues with the fuel injection system, such as dirty or clogged injectors. When too much diesel is injected without sufficient air for proper mixing, unburned fuel results in black smoke from the exhaust. Another cause is insufficient air supply – a clogged air filter or faulty turbocharger reduces air intake, forcing the engine to work harder and inject more fuel, leading to black smoke. If the EGR system malfunctions, reduced exhaust gas recirculation can raise combustion temperatures and potentially cause smoke. While the SCR system uses urea to treat exhaust, its failure doesn't directly cause black smoke – the root issue usually lies with the engine components. Ignoring this increases fuel consumption, pollution, and vehicle damage. My advice is to stop driving immediately, check for warning lights, then visit a professional shop to scan for trouble codes. It's likely a fuel injection or air intake component issue – cleaning or replacing the parts should solve it. Don't delay as it worsens the problem.

[DeKiara]

When I work on cars, I pay special attention to engine issues. Black smoke from urea-equipped vehicles is quite common in diesel cars, and the root cause is usually an imbalance in the fuel-to-air ratio. Focus on the fuel injection system: stuck injectors spraying too much fuel or unstable high-pressure pump pressure can both lead to incomplete fuel combustion. The intake system is also crucial—a dirty air filter, leaks in the intake manifold, or failing turbocharger blades can cause a shortage of air supply, directly resulting in thick black smoke. If the EGR valve is stuck, insufficient exhaust gas recirculation and low combustion efficiency can also easily cause smoke. Although SCR system issues don’t directly cause black smoke, if it malfunctions, the engine might be poorly tuned, indirectly affecting performance. I’ve also found that poor fuel quality is a factor, as using low-grade diesel increases carbon buildup. I recommend running a full scan with an onboard diagnostic tool to check for any fault codes. For routine maintenance, remember to regularly replace the air filter and clean the fuel injection components to prevent minor issues from turning into major problems.

[MargaretDella]

When I drive a urea-powered vehicle and encounter black smoke, I get nervous and worry about safety. This situation is mostly due to incomplete fuel combustion: the injectors spray too much fuel without enough air to match; a dirty air filter blocks airflow, hindering intake and causing poor mixture; a malfunctioning turbo can also add to the trouble. An SCR system not working properly usually doesn’t cause black smoke, but it may trigger the exhaust treatment warning light. I recommend pulling over immediately—don’t force the drive to avoid danger or fines. Do a quick self-check on the air filter’s condition; if it’s fine, head to the repair shop to inspect the fuel injection and electrical systems. Handling it well can save fuel and protect the environment—don’t delay and waste money or damage the car.