What are the reasons for unqualified vehicle exhaust?
2 Answers
Reasons for unqualified vehicle exhaust include: 1. High sulfur and phosphorus content in gasoline, which can form chemical complexes on the surface of the oxygen sensor and the three-way catalytic converter; 2. Congested urban roads, frequent vehicle starts and stops, and idling, leading to incomplete combustion products adhering to the surface of the three-way catalytic converter; 3. Carbon deposits and particulate matter in the engine can clog the three-way catalytic converter. Solutions for unqualified vehicle exhaust: 1. Shift to 4th gear and drive at 5th gear speed for several dozen kilometers; 2. Keep the engine warm, do not turn it off while idling, and rev the engine in neutral for 3 to 5 minutes before inspection; 3. Regularly clean the three-way catalytic converter.
Last time I helped my neighbor check for excessive exhaust emissions, the most common issues were a clogged or poisoned catalytic converter. This part acts like a filter, and over time, carbon buildup or using low-quality gasoline can cause it to fail. A faulty oxygen sensor can also cause trouble—it controls the fuel injection, and if it's broken, it will inject too much fuel, leading to incomplete combustion. Additionally, bad spark plug ignition, a dirty air filter affecting air intake, or even worn piston rings in older cars causing blue smoke from burning oil can all contribute to foul-smelling exhaust. I usually recommend checking the trouble codes first and using a borescope to inspect carbon buildup in the cylinders, which is much better than blindly replacing parts.
