Why Do Vehicle Emissions Exceed Standards?

[DiGrace]

Here is an introduction to excessive vehicle emissions: Vehicle Aging: If a vehicle has traveled more than 450,000 kilometers or been in use for over 15 years, its various components will show significant aging, poor contact, weak sealing, and insufficient pressure. Failure of the Three-Way Catalytic Converter: The failure of the three-way catalytic converter is the primary reason for excessive vehicle emissions. The three-way catalytic converter, installed in the vehicle's exhaust system as the most important external purification device, converts harmful gases such as CO, HC, and NOx in vehicle emissions into harmless carbon dioxide, water, and nitrogen through oxidation and reduction reactions. When high-temperature vehicle emissions pass through the purification device, the catalyst in the three-way catalytic converter enhances the activity of CO, HC, and NOx, promoting specific oxidation-reduction chemical reactions. CO oxidizes at high temperatures into colorless, non-toxic CO2 gas; HC compounds oxidize into water (H2O) and CO2; and NOx reduces into nitrogen and oxygen. These three harmful gases are transformed into harmless gases, thereby purifying vehicle emissions. Abnormal Engine Operation: The engine may experience issues such as cylinder misfiring, spark plug oil leakage, or oil mixing. When accelerating, the engine does not run smoothly or powerfully.

[Melanie]

I drove a taxi for over a decade, and excessive exhaust emissions usually stem from low engine combustion efficiency. In older vehicles, insufficient cylinder pressure and severe piston ring wear cause gas leakage, leading to incomplete combustion of the air-fuel mixture and excessive CO and HC emissions. Neglecting regular maintenance, such as failing to replace air filters or oil filters on time, allows dust buildup that blocks airflow and affects air supply. Frequent sudden acceleration or prolonged low-speed crawling during driving raises oil temperature excessively, accelerating catalytic converter failure. It's best to regularly clean the throttle body, inspect the ignition system, ensure proper air-fuel ratio, and develop the habit of warming up the engine to effectively prevent emission exceedance issues.