What Causes Excessive Exhaust Emissions?
2 Answers
Vehicle aging and other factors. Detailed explanations for excessive exhaust emissions are as follows: Vehicle aging: If the vehicle's mileage exceeds 450,000 kilometers or has been in use for more than 15 years, various components of the car will show significant aging, poor contact, poor sealing, insufficient pressure, and other phenomena. Engine malfunction: The engine may experience issues such as cylinder misfiring, spark plug oil leakage, or oil mixing. When the throttle is increased, the engine does not run smoothly and powerfully. Oxygen sensor damage: In engines using a three-way catalytic converter to reduce exhaust pollution, the oxygen sensor is an essential component. It detects the oxygen concentration in the exhaust and sends feedback signals to the ECU. The ECU then adjusts the fuel injector's fuel quantity to control the air-fuel ratio of the mixture near the theoretical value, ensuring more complete fuel combustion.
Last time my friend also failed the annual inspection due to excessive exhaust emissions, and it took a lot of effort to fix. Here are the main issues we learned: Poor fuel quality is the worst—small gas stations have impurities in their fuel, leading to incomplete combustion; a dirty air filter, clogged like a rag, disrupts the air-fuel mixture ratio; weak spark from worn-out spark plugs causes incomplete burning, making the exhaust smell bad; carbon buildup on the oxygen sensor confuses the ECU on how to adjust fuel injection; and the most troublesome is a failed catalytic converter—it’s expensive, but it’s the key component for treating exhaust. Oh, and air leaks in older cars can also cause excessive emissions, so it’s worth checking the cylinder head gasket or valve seals.
