* Dirty or Faulty Throttle Body: The throttle body is the mechanism that controls airflow into the engine. Accumulated grime can disrupt its operation, leading to a rough idle and stalling. Cleaning it is often a relatively inexpensive and effective first step.
* Faulty Idle Air Control (IAC) Valve: This valve regulates air flow at idle. If it's dirty or malfunctioning, it can't maintain the correct air/fuel mixture, resulting in a rough idle and stalling. Cleaning or replacement may be needed.
* Mass Airflow Sensor (MAF) Sensor Problems: The MAF sensor measures the amount of air entering the engine. A dirty or faulty MAF sensor provides inaccurate readings, leading to poor fuel mixture and rough running. Cleaning it (carefully!) or replacement might be necessary.
* Vacuum Leaks: Cracks or holes in vacuum hoses can disrupt the engine's air/fuel mixture, causing a rough idle and stalling. Inspect all vacuum hoses for damage.
* Spark Plugs and Wires: Worn-out spark plugs or damaged spark plug wires can prevent consistent ignition, leading to a rough idle and misfires that can cause stalling. Check for wear and tear and replace if necessary.
* Crank Position Sensor (CKP) or Camshaft Position Sensor (CMP) Issues: These sensors tell the engine's computer where the crankshaft and camshaft are positioned. If faulty, the engine's timing is affected, leading to rough running and stalling.
* Fuel Delivery Problems: A clogged fuel filter, weak fuel pump, or problems with fuel injectors can prevent the engine from receiving enough fuel, leading to stalling, especially at low speeds when fuel demand is lower.
* PCV Valve: A clogged positive crankcase ventilation (PCV) valve can cause excessive crankcase pressure, affecting engine performance and leading to a rough idle.
Troubleshooting Steps:
1. Check for error codes: Use an OBD-II scanner to read any diagnostic trouble codes (DTCs) stored in the car's computer. This will provide valuable clues about the problem.
2. Visual Inspection: Start with a visual inspection of vacuum hoses, spark plug wires, and the throttle body for visible signs of damage or debris.
3. Clean the Throttle Body and IAC Valve: This is often the easiest and cheapest first step. Use a throttle body cleaner and follow instructions carefully.
4. Check the Fuel Filter: This is relatively simple and inexpensive.
Important Note: If you are not comfortable working on your car, take it to a qualified mechanic. Improper diagnosis or repair can lead to further damage. Trying to fix the problem yourself without the necessary knowledge and tools can be risky.
