Fuel System:
* Fuel Pump: Weak fuel pump. It might be delivering insufficient fuel pressure when cold, improving only as the engine warms and the pump gets less viscous fuel. Listen for the fuel pump whirring when you turn the key to the "on" position (before cranking). A weak whir or no whir is a strong indicator. Fuel pressure testing is definitive.
* Fuel Filter: A clogged fuel filter restricts fuel flow, especially problematic when cold fuel is thicker. Replacement is cheap and relatively easy.
* Fuel Injectors: Clogged or failing injectors might not deliver enough fuel for a cold start. This requires more advanced diagnostics.
* Fuel Pressure Regulator: A failing regulator could be leaking pressure overnight, leading to a hard start in the morning.
Ignition System:
* Ignition Coil: A weak coil might not provide sufficient spark energy when cold.
* Spark Plugs & Wires: Worn or fouled spark plugs or cracked/worn spark plug wires can impede ignition, especially when cold. Check for cracking, corrosion, and proper gap on the plugs.
* Distributor Cap & Rotor: (If equipped) These components can degrade and cause a poor spark. Look for cracks, arcing, or corrosion.
* Crankshaft Position Sensor (CKP): This sensor tells the computer the engine's rotational position. A failing sensor can prevent proper ignition timing.
* Throttle Position Sensor (TPS): While less likely the primary cause, a faulty TPS can affect cold start fuel delivery.
Other Possibilities:
* Battery: A weak battery can struggle to crank the engine sufficiently, especially in cold weather. Test the battery's voltage and cranking amps.
* Starter Motor: A failing starter motor might not deliver enough power to turn the engine over quickly enough.
* Intake Air Temperature Sensor (IAT): An inaccurate IAT sensor can cause the computer to use incorrect fuel mixture calculations, leading to poor starting.
* EGR Valve: A sticky or malfunctioning EGR valve can lean out the fuel mixture, making cold starts difficult.
Troubleshooting Steps:
1. Start with the basics: Check the battery, and visually inspect the spark plugs and wires. Replacing these are relatively inexpensive first steps.
2. Listen for the fuel pump: Does it prime when you turn the key?
3. Check the air filter: A severely clogged filter restricts airflow.
4. Consider the weather: Cold weather significantly exacerbates starting problems.
Professional Help:
If you're not comfortable working on your car yourself, a qualified mechanic can perform diagnostic tests to pinpoint the exact problem. They have specialized tools (like a fuel pressure gauge) to diagnose fuel system issues, and can check the ignition system components more effectively. The age of the vehicle suggests multiple components may be nearing end-of-life.
Remember safety first! Disconnect the negative battery terminal before working on any electrical components.
