Performance Issues:
* Rough idle: The engine may shake or vibrate noticeably, especially at idle. This is a classic symptom.
* Hesitation or stumbling: The engine may hesitate or stumble when accelerating, especially from a stop.
* Lack of power: The car may feel sluggish and lack its usual acceleration.
* Misfires: The engine may misfire, causing a rough running condition and potentially setting a check engine light. This is often accompanied by a noticeable popping or backfiring sound from the exhaust.
* Poor fuel economy: A bad injector can lead to significantly reduced fuel efficiency.
Emissions Issues:
* Check engine light: A malfunctioning fuel injector will almost certainly trigger the check engine light. A code reader is needed to diagnose the specific problem. Common codes associated with fuel injectors include those related to misfires in a specific cylinder.
* Excessive emissions: A bad injector can cause incomplete combustion, leading to higher levels of pollutants in the exhaust.
Other Symptoms:
* Black smoke from the exhaust: Excessive fuel being injected can cause black smoke from the tailpipe. However, this is more likely with multiple failing injectors or other issues.
* Fuel smell: A leaking injector can cause a strong fuel odor.
* Hard starting: While less common, a severely clogged injector can make starting the engine difficult.
Important Note: Many of these symptoms can also be caused by other problems, such as a bad ignition system, vacuum leaks, or problems with the mass airflow sensor. A proper diagnosis requires a mechanic to check the fuel pressure, perform a fuel injector test, and scan the car's computer for diagnostic trouble codes (DTCs). Don't just assume it's a fuel injector based on one or two symptoms.
