What are the reasons for excessive NOx emissions in vehicles?
2 Answers
Excessive NOx emissions in vehicles are caused by clogged fuel injectors, which result in excessively high oxygen levels inside the engine. The immediately emitted CH and CO from the engine are too low to reduce NOx, thus affecting the vehicle's exhaust emissions to exceed standards. Vehicle exhaust is the waste gas produced during vehicle use, containing hundreds of different compounds. The pollutants include solid suspended particles, carbon monoxide, carbon dioxide, hydrocarbons, nitrogen oxides, lead, sulfur oxides, etc. Sulfur dioxide in the exhaust has a strong irritating odor and, when reaching certain concentrations, can easily lead to acid rain, causing soil and water acidification, and affecting the growth of crops and forests.
Oh, speaking of excessive NOx emissions in cars, I think of my twenty years of driving experience. This kind of problem is very common. The main issue is a faulty catalytic converter—that thing is specifically designed to treat exhaust gases. Once it fails, nitrogen oxide levels skyrocket. When the engine burns fuel too aggressively and the temperature gets too high, it also produces more NOx, especially if the air-fuel ratio is off or the oxygen sensor malfunctions, causing the ECU (engine control unit) to go haywire. Older cars are more prone to exceeding emissions standards because of poor maintenance, like not changing the oil or excessive carbon buildup. Last year, my old car failed the emissions test, and it only passed after fixing the catalytic converter. Exceeding emissions standards not only means failing the inspection but also worsens urban smog, harming both others and yourself. Go to a 4S shop and get it checked as soon as possible—don’t wait for something bad to happen.
