* Throttle Position Sensor (TPS): A faulty TPS might provide inaccurate readings to the engine computer (ECM) when cold. This could lead to improper fuel delivery or ignition timing, causing a stall. The sensor often works better once it warms up.
* Mass Airflow Sensor (MAF): Similar to the TPS, a dirty or malfunctioning MAF sensor will give inaccurate readings of the air entering the engine. Cold, dense air readings can be especially affected, leading to a lean condition and stalling. Cleaning the MAF sensor (carefully!) is often a first step in troubleshooting.
* Fuel Injector Issues: Cold fuel can be more viscous, and injectors might struggle to atomize it properly if they are worn, dirty, or have low pressure. This would be more pronounced when cold, improving as the engine warms and the fuel thins. Check fuel pressure.
* Coolant Temperature Sensor (CTS): The ECM uses the CTS reading to determine how to adjust fuel mixture and ignition timing for optimal cold starting. A faulty CTS provides inaccurate temperature readings, leading to poor cold-start operation.
* Ignition System (Coil, Wires, Distributor): While less common, a weak ignition system might struggle to ignite the fuel-air mixture effectively when cold. This would improve as the engine warms. Check for cracked or worn spark plug wires, weak ignition coil, or other ignition components.
* Idle Air Control (IAC) Valve: The IAC valve regulates air flow at idle. A dirty or malfunctioning IAC valve could lead to stalling, particularly when cold.
* Vacuum Leaks: Vacuum leaks can impact air/fuel mixture, leading to a rough idle or stalling, especially when cold.
Troubleshooting Steps:
1. Check for error codes: Use an OBD-II scanner to retrieve any diagnostic trouble codes (DTCs) stored in the ECM. These codes will often point directly to the faulty component.
2. Inspect visually: Look for obvious signs of damage or wear to the components mentioned above, particularly vacuum lines, wiring, and connections.
3. Clean sensors: Carefully clean the MAF and TPS sensors with a MAF sensor cleaner (following the manufacturer's instructions precisely).
4. Test fuel pressure: Have a mechanic or use a fuel pressure gauge to check fuel pressure.
5. Replace parts: If you find faulty components, replace them with high-quality parts. Often starting with the cheapest and easiest to replace components (MAF sensor cleaning) is a good starting point.
It's advisable to take the vehicle to a qualified mechanic if you are not comfortable diagnosing and repairing automotive electrical and fuel systems. Incorrect diagnoses can lead to further damage or unsafe operating conditions.
