Fuel System Issues:
* Fuel Pump Failure: A failing fuel pump can't deliver enough fuel to the engine, leading to power loss and stalling. This is a common cause.
* Clogged Fuel Filter: A dirty fuel filter restricts fuel flow, causing similar symptoms.
* Fuel Injectors: Faulty injectors might not be delivering fuel properly or consistently. Clogged or leaking injectors are possibilities.
* Low Fuel Pressure: Problems with the fuel pressure regulator can cause inconsistent fuel delivery.
Ignition System Issues:
* Crankshaft Position Sensor (CKP): This sensor tells the computer the engine's rotational position. A faulty CKP sensor can cause misfires and stalling.
* Cam Position Sensor (CMP): Similar to the CKP sensor, a faulty CMP sensor can disrupt engine timing and lead to stalling.
* Ignition Coil(s): Worn or failing ignition coils can prevent one or more cylinders from firing, resulting in power loss and stalling.
* Spark Plugs & Wires: Worn or damaged spark plugs or ignition wires can lead to misfires.
Other Potential Causes:
* Mass Airflow Sensor (MAF): This sensor measures the amount of air entering the engine. A faulty MAF sensor can cause the engine to run lean or rich, leading to power loss.
* Throttle Position Sensor (TPS): This sensor monitors the throttle position. A faulty TPS can cause erratic engine performance and stalling.
* Computer Problems (PCM/ECM): The Powertrain Control Module (PCM) or Engine Control Module (ECM) controls many engine functions. A malfunctioning PCM can cause a wide range of problems, including stalling.
* Alternator: A failing alternator might not charge the battery sufficiently, leading to power loss and stalling.
* Vacuum Leaks: Leaks in the vacuum system can disrupt engine performance.
* Transmission Issues (if automatic): Though less likely to cause a sudden stall, transmission problems *could* contribute, especially if the transmission suddenly stops engaging.
Troubleshooting Steps:
1. Check the obvious: Start with the simplest things: Make sure the fuel tank isn't empty. Check the battery voltage. Look for any obvious damage to wiring or connectors.
2. Diagnostic Codes: Use an OBD-II scanner to read any diagnostic trouble codes (DTCs) stored in the PCM. These codes can pinpoint the problem area.
3. Professional Inspection: If you're not comfortable diagnosing these issues yourself, take the Expedition to a qualified mechanic. They have the tools and expertise to diagnose and repair the problem efficiently and safely.
It's impossible to definitively diagnose the problem without further information or a diagnostic scan. The symptoms you describe are quite common and can be caused by several different components. Getting the codes read is the first crucial step.
