* Multiple Injector Problems: A single failing injector can sometimes trigger a cascade of issues, affecting the engine's timing and fuel mixture. It's possible other injectors are failing or nearing failure. A failing injector can cause a misfire (shaking), and excessive fuel in the exhaust can create a gas smell.
* Ignition System Issues: Even with a new injector, a problem with the ignition system (spark plugs, wires, coil packs, distributor – depending on your engine type) can cause misfires and rough running. A weak spark could prevent proper combustion, leading to unburnt fuel (gas smell) and rough idling/shaking.
* Fuel Pressure Regulator: A faulty fuel pressure regulator can cause inconsistent fuel pressure, leading to erratic fuel delivery to the injectors. This would affect multiple injectors, not just one.
* Mass Airflow Sensor (MAF) or Throttle Position Sensor (TPS): These sensors provide crucial information to the engine's computer about the amount of air and throttle position. Faulty sensors can lead to incorrect fuel mixture calculations, resulting in misfires, rough running, and a gas smell.
* Computer (PCM/ECM): Though less likely, a problem with the engine control module (the computer) can cause misfires and incorrect fuel delivery. This is usually indicated by multiple sensor-related codes.
* Vacuum Leaks: Leaks in the vacuum system can disrupt the proper operation of various engine components, leading to poor performance and a rough idle.
What you should do:
1. Get a proper diagnostic scan: Take the vehicle to a reputable mechanic or auto parts store that offers OBD-II diagnostics. The check engine light code(s) will provide much more specific information about the problem. A generic code reader might not reveal the full story.
2. Check all the injectors: While injector #6 was replaced, it's crucial to test the other injectors' performance to rule out further issues within the fuel injection system. A fuel injector cleaner might help temporarily improve things, but it won't fix a truly failing injector.
3. Inspect the ignition system: Visually inspect the spark plug wires, spark plugs, and coil packs (or distributor) for signs of wear, damage, or cracking. These components should also be tested for proper function.
4. Address any vacuum leaks: A mechanic can use a vacuum gauge to check for leaks in the vacuum system.
Ignoring the problem could lead to further damage, potentially requiring more expensive repairs. A professional diagnosis is essential to pinpoint the root cause and fix it properly.
