What effect does incomplete combustion from a fuel injector leak generally have?

Incomplete combustion due to a fuel injector leak primarily results in higher fuel consumption. When fuel injectors do not function correctly, either by leaking or not atomizing the fuel properly, it can lead to an excess of unburned fuel entering the combustion chamber. Since the fuel is not fully utilized during the combustion process, more fuel is required to maintain the desired power output or engine performance.

As a result, the engine compensates for the lost efficiency by injecting more fuel to achieve the same power, which ultimately raises overall fuel consumption. This situation not only wastes fuel but can also lead to other issues like fouling of spark plugs and increased deposits on engine components. It is an indicator of an engine running poorly and can have a significant impact on operational costs and environmental impact.

In contrast, the other options reflect outcomes that would not be expected from a condition of incomplete combustion. Higher engine efficiency, reduced emissions, and improved engine performance are typically associated with optimal fuel injector function and complete combustion processes, so they do not apply in this scenario.