* Worn or Damaged Ignition Wires: These wires carry high voltage to the spark plugs. If the insulation is cracked or deteriorated, moisture can easily cause arcing (short circuits) and misfires, leading to skipping and backfiring. Dampness exacerbates this because it provides a conductive path for the electricity to leak.
* Faulty Spark Plug Wires: Similar to the ignition wires, faulty spark plug wires can lead to misfires and backfires, especially in wet conditions. Cracks or damage in the wire insulation allow moisture to penetrate and cause shorts.
* Distributor Cap and Rotor (if applicable): Older vehicles like some Windstars might have a distributor. Moisture inside the distributor cap can cause arcing between the terminals, leading to erratic spark delivery and the symptoms you describe. The rotor, which rotates inside the cap, can also develop cracks that allow moisture to enter.
* Worn or Damaged Spark Plugs: While less directly linked to dampness, worn spark plugs can misfire more readily in humid conditions. The spark might not be strong enough to ignite the fuel reliably, causing a skip. A backfire might occur if the spark happens too late.
* Ignition Coil(s): The ignition coil(s) boost the voltage from the battery to create the spark. A failing coil, particularly one with damaged insulation, can malfunction more frequently in wet conditions, leading to misfires.
* Crankshaft Position Sensor (CKP): A faulty CKP sensor can cause misfires. While not directly affected by moisture, a damaged sensor can be more prone to malfunctioning in damp conditions due to corrosion or electrical short circuits.
Troubleshooting Steps:
1. Visual Inspection: Carefully inspect all ignition wires, the distributor cap and rotor (if present), and spark plugs for any visible damage, cracks, or corrosion. Look for signs of moisture penetration.
2. Check Spark Plug Wires for Arcing: With the engine off and in a dark environment, have someone crank the engine while you observe the wires for any sparks jumping between them or to the engine block. This is a strong indicator of damaged insulation.
3. Replace Spark Plugs and Wires: This is often the most effective solution, especially if the components are old or show signs of wear. Replacing them proactively is a relatively inexpensive fix.
4. Inspect and/or Replace Distributor Cap and Rotor (if applicable): If your Windstar has a distributor, check its condition carefully for cracks, corrosion, or moisture.
5. Professional Diagnosis: If you're uncomfortable performing these checks yourself, it's best to take your vehicle to a qualified mechanic. They can perform more thorough diagnostics, including checking for other potential issues (like the CKP sensor) and using specialized equipment to pinpoint the problem.
Remember safety first! Always disconnect the negative battery terminal before working on any electrical components in your vehicle.
