Why is the Exhaust Pipe Very Black?

[VanJameson]

Insufficient combustion of automotive fuel, leading to carbon deposits, is the fundamental reason for the blackening of the exhaust pipe. Here is relevant information: 1. If the engine cannot fully combust, some of the unburned or incompletely burned fuel vapor will be carbonized when passing through the catalytic converter. These carbon deposits accumulate at the exhaust pipe outlet, and over time, they cause the exhaust pipe to turn black. 2. Normal blackening of the exhaust pipe is generally related to factors such as direct-injection turbocharging, prolonged idling warm-up time, and poor air quality, as these factors, to varying degrees, affect the combustion of the air-fuel mixture. However, if low-quality gasoline is used or there is a catalytic converter malfunction, these conditions can exacerbate the symptoms of the exhaust pipe blackening.