What to Do When a Car Shows Excessive Exhaust Emissions on the Road?

[SanHailey]

If a car shows excessive exhaust emissions on the road, a routine inspection of the exhaust is necessary. The on-road exhaust emission test is a type of remote sensing monitoring. Remote sensing monitoring has low accuracy and is not used as legal evidence; it is merely for screening purposes. There are four methods for monitoring vehicle exhaust emissions: single idle speed method, double idle speed method, steady-state operating mode method, and simple transient operating mode method. The single idle speed method has been phased out due to its simplicity and higher detection data limits. The simple transient operating mode method is more scientific than the double idle speed method and steady-state operating mode method, providing more accurate detection data. The simple transient method is a load-bearing test method, and its results can effectively reflect the actual emission conditions of the vehicle on the road. It is a scientific, advanced, and practical detection method. Compared to the double idle speed method, it has a lower misjudgment rate, effectively prevents tampering, and can also detect nitrogen oxide emissions, providing more scientific and objective data for vehicle supervision. Here are the methods to address excessive vehicle exhaust emissions: Clean or Replace the Three-Way Catalytic Converter: The three-way catalytic converter is a significant factor in excessive vehicle exhaust emissions. In many cases, excessive emissions are caused by issues with the three-way catalytic converter. Its function is to oxidize CH and CO into carbon dioxide and H2O. If the three-way catalytic converter malfunctions, passing the exhaust emission test becomes difficult. Common issues include carbon buildup, clogging, poisoning, or failure. Cleaning the three-way catalytic converter can resolve some issues, but if it is poisoned or damaged, timely replacement is necessary. Clean or Replace the Spark Plugs: Faulty spark plugs can also lead to excessive exhaust emissions. The most common issue with spark plugs is carbon buildup, which can be cleaned using sandpaper or a cleaning agent. If the spark plugs fail due to erosion or reaching the end of their lifespan, they should be replaced immediately to avoid affecting normal vehicle operation. Check the Oxygen Sensor: When the oxygen sensor is covered in carbon buildup or malfunctions, it affects the ECU's ability to correctly adjust the air-fuel mixture and may also impact the normal operation of the three-way catalytic converter. It is recommended to clean the oxygen sensor and the three-way catalytic converter together. Perform a Deep Engine Cleaning: After detecting excessive exhaust emissions, a thorough engine cleaning—including the throttle body, fuel lines, intake manifold, and fuel injectors—can restore the engine to normal working condition.