What are the reasons for a new car failing the exhaust emission test?
2 Answers
The reasons for a new car failing the exhaust emission test include high sulfur and phosphorus content in gasoline, frequent vehicle start-stop and idling, incomplete combustion, and clogging of the three-way catalytic converter by carbon deposits and particulate matter in the engine. Solutions: Replace spark plugs; clean the contacts of the distributor and distributor rotor; adjust ignition timing; clean the air filter; use cleaning agents to clean the throttle body; clean the three-way catalytic converter and oxygen sensor, among other methods. Automotive exhaust emission testing standards: Automotive exhaust emission testing is based on whether the smoke opacity value meets the standards, and whether the emissions meet the standards is primarily determined by the vehicle's testing data, confirming compliance based on the smoke opacity value. If the exhaust emission values do not meet the standards, the annual inspection will not pass. The environmental standards for automotive exhaust emission testing are: the limit for carbon monoxide is 6.3g/km, and the total limit for hydrocarbons and nitrogen oxides is 2.0g/km.
The new car failed the exhaust emission test, and I suspect it might be due to the break-in period. When the car just rolls off the production line, the engine and exhaust system haven't fully smoothed out, leading to incomplete fuel combustion. Common causes include a faulty oxygen sensor, which monitors the air-fuel ratio—any assembly errors in a new car can easily result in excessive emissions. Another issue could be a clogged or improperly activated catalytic converter, possibly damaged during transportation. Additionally, poor fuel quality, such as using low-grade gasoline with more residues, can affect exhaust emissions. It's recommended to visit the dealership for a check-up, adjust engine parameters, or replace sensors promptly. Delaying isn't advisable because exhaust issues not only affect the test but also worsen air pollution. Using higher-grade fuel regularly can help prevent such problems.
