A faulty or defective fuel injector can cause a series of problems that can negatively impact a car's engine performance. What follows is a brief description of the most common signs of a bad automotive fuel injector.
Rough Engine Idle
A car that has a bad fuel injector will often have a rough, or choppy, engine idle. A fuel injector is responsible for injecting fuel directly into the engine cylinder where it is burnt during combustion; if this fuel delivery is compromised, a rough engine idle can result.
A bad fuel injector can develop cracks or breaks in its body, especially where it connects to the intake manifold. If this happens, fuel can leak out onto the intake manifold, an occurrence that can be both seen and smelled.
Engine missing, along with a rough idle, is a common symptom of a bad fuel injector. A bad fuel injector can restrict or stop fuel flow from being injected into an engine cylinder properly, which can negatively impact fuel combustion and affect engine performance, resulting in missing, a rough idle or misfiring.
A faulty fuel injector can cause an irregular or disrupted flow of fuel into the engine, a condition that can cause an engine to surge or alternate between high and low rpm (revolutions per minute) continuously throughout engine operation. This results in a very up-and-down, choppy mode of engine operation.
Poor Gas Mileage
A leaky or malfunctioning fuel injector can adversely affect a car's gas mileage. A leaky fuel injector can waste fuel by allowing it to leak out of the fuel injector housing instead of being injected directly into the engine; a malfunctioning fuel injector can cause too much fuel to be injected into the engine. Both conditions result in excess fuel being wasted, which in turn negatively affects gas mileage.