What to Do If Vehicle Inspection Shows Excessive HC in Exhaust?
2 Answers
Solutions for excessive HC in exhaust: Use higher-grade gasoline. Higher-grade gasoline is cleaner and significantly reduces the content of harmful gases such as CO, NO, and HC after combustion. During annual vehicle inspections, using higher-grade gasoline can help purify the exhaust, making it easier to pass the inspection. Here is additional information: 1. Importance of the Three-Way Catalytic Converter: Exhaust gases are emitted through the exhaust pipe, and the three-way catalytic converter on the exhaust pipe is the most important external purification device in the vehicle's exhaust system. It converts harmful gases such as CO and HC in the exhaust into harmless carbon dioxide, water, and nitrogen. Long-term neglect of the three-way catalytic converter's maintenance can lead to blockage, reducing its ability to convert harmful gases and ultimately causing the exhaust emissions to fail standards. If the three-way catalytic converter is malfunctioning, specialized cleaning agents can be used for cleaning, or it can be directly replaced if the blockage is severe. 2. Delaying Ignition Timing to Reduce Exhaust Emissions: Delaying the ignition timing shortens the combustion time in the combustion chamber and lowers the peak combustion temperature, thereby reducing the emission of hydrocarbons and nitrogen oxides. However, this will result in a decrease in engine power. Commonly referred to as adjusting the ignition timing, this involves reducing the timing to the limit, as long as the vehicle can still reach 100 km/h on the ring road. If the adjustment is too delayed, the vehicle may not perform well, but the timing can be readjusted after the inspection.
I often encounter cases where vehicle inspection fails due to excessive HC emissions, primarily caused by incomplete engine combustion. First, check the oxygen sensor. If it malfunctions, the system cannot properly adjust the air-fuel ratio, leading to high hydrocarbon emissions. Worn or carbon-fouled spark plugs are also a common issue, resulting in weak ignition and incomplete fuel combustion. A clogged or failed catalytic converter could be another cause, as it is responsible for converting harmful gases; if it fails, HC levels will exceed standards. Dirty fuel system components, such as carbon buildup in fuel injectors, can also affect the air-fuel mixture. For diagnosis, it's best to use professional equipment to read fault codes and replace parts or clean accordingly. Regular engine maintenance and using cleaning additives can prevent such issues. Before the annual inspection, warming up the engine and driving at high speeds can also improve emission performance.
