Is it normal for a new car's exhaust pipe to have a little black residue when touched by hand?
1 Answers
It is not normal for a new car's exhaust pipe to have black residue. However, it is normal for the exhaust pipe to turn black after the car has been driven for some time. Below are the relevant explanations: Poor spark plug performance: When the car is in a cold-start condition, if the spark plugs are not functioning properly, the air-fuel mixture will not burn completely, resulting in large amounts of black smoke. Aging engine: If the engine has been used for too many years, its overall performance will degrade, causing the car to only spray gasoline without properly combining it with air for combustion. This leads to excessive black smoke, which blackens the exhaust pipe. Incorrect engine timing or ignition timing: Such timing discrepancies can prevent oxygen and engine oil from fully mixing and burning.