Here's why:
* Rich Mixture: A rich mixture means there's too much fuel and not enough air in the combustion chamber.
* Incomplete Combustion: The excess fuel doesn't burn completely, leading to incomplete combustion.
* Soot Formation: Incomplete combustion produces soot, which is tiny particles of carbon. These soot particles are what give the exhaust its black color.
Other signs of a rich mixture include:
* Reduced engine power: The excess fuel hinders efficient combustion.
* Rough idling: The engine may struggle to run smoothly at idle.
* Increased fuel consumption: More fuel is being used, but not burned efficiently.
* Fuel smell: You may smell unburnt fuel coming from the exhaust.
It's important to address a rich mixture as it can damage the engine over time.
