A fuel injector is actually a combination of a nozzle and valve that controls the delivery of fuel into the combustion chamber of an engine. The nozzle is carefully designed to atomize fuel in a very fine spray to achieve a homogenous mixture of air and fuel. A failing or clogged injector can cause incomplete burn and/or a dangerous lean condition in a cylinder. This can present itself as a misfire, hesitation, stumbling, or low power. Leaking fuel injectors can have symptoms such as hard starting, poor emissions, increased fuel consumption, damaged catalytic converters, and increase fuel odor in and around the car. Some success can be had with fuel injector cleaner but it is critical to an engine’s performance and life that properly functioning fuel injectors be used at all times.