* Fuel Injectors: Clogged or faulty fuel injectors can cause an inconsistent fuel supply, leading to erratic idling, bogging, and stalling. The fuel smell from the exhaust points towards this as unburnt fuel is being expelled.
* Fuel Pump: A weak or failing fuel pump might not be delivering enough fuel pressure, resulting in similar symptoms. The engine struggles under load (when in gear) because it's starved of fuel.
* Mass Airflow Sensor (MAF) Sensor: A dirty or malfunctioning MAF sensor provides inaccurate readings of the air intake, causing the engine's computer (ECU) to deliver the wrong air/fuel mixture. This can lead to rough idling and stalling.
* Throttle Position Sensor (TPS): Similar to the MAF sensor, a faulty TPS provides incorrect information to the ECU about the throttle position, leading to poor engine control.
* Oxygen Sensor (O2 Sensor): A malfunctioning O2 sensor provides inaccurate feedback on the exhaust gases, causing the ECU to adjust the air/fuel mixture incorrectly. This can contribute to the erratic running and fuel smell.
* Vacuum Leaks: Leaks in the intake system can disrupt the air/fuel mixture, causing erratic idling and poor performance.
* Catalytic Converter: While less likely to be the *primary* cause of these symptoms, a clogged catalytic converter can restrict exhaust flow, leading to back pressure that affects engine performance and might contribute to the smoke (though the smoke likely comes from the rich mixture before the converter).
What to do:
1. Check for diagnostic trouble codes (DTCs): Use an OBD-II scanner to read any trouble codes stored by the car's computer. This will provide valuable clues about the potential problem.
2. Visual Inspection: Check for obvious signs of damage or leaks in the fuel lines, vacuum hoses, and intake system.
3. Professional Diagnosis: Given the combination of symptoms, it's highly recommended to take your car to a qualified mechanic for a proper diagnosis. They have the tools and expertise to test the fuel pressure, check the fuel injectors, and diagnose other potential issues. Attempting repairs without proper diagnosis could worsen the problem or even cause damage to the engine.
Ignoring this issue could lead to further damage to your engine, so it's crucial to address it promptly. The smoke and fuel smell indicate that unburnt fuel is entering the exhaust, which isn't just inefficient but also a potential fire hazard.
