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.