What happens when combustion is too rich?

When combustion is too rich, meaning there is an excess of fuel relative to air in the combustion mixture, the engine tends to experience misfires and inefficient performance. This occurs because there is not enough oxygen present to fully combust the additional fuel. As a result, the fuel does not burn completely, leading to unburned fuel being expelled with the exhaust gases. This can cause a number of issues, including rough idling, poor acceleration, and increased emissions due to the presence of unburned hydrocarbons.

The efficiency of the engine is compromised in this scenario, as desired performance relies on a proper air-fuel mixture that allows for complete combustion. An excessively rich mixture may also contribute to carbon buildup in the engine, further impairing its operation over time. Understanding this balance is critical for maintaining optimal engine performance and reducing emissions.