1. Verify the Spark Plug and Wire Replacement:
* Correct Installation: Double-check that you installed the new spark plugs and wires correctly. Ensure the plugs are tightened to the manufacturer's specified torque (don't overtighten!). Make sure each wire is securely connected to both the spark plug and the distributor cap (if applicable) or coil pack. A loose connection is a common cause of misfires.
* Visual Inspection: Carefully inspect the new spark plugs and wires for any damage. Look for cracks, burn marks, or other signs of wear. A faulty new part is possible, though less likely.
2. Investigate Ignition System Components (Beyond Plugs and Wires):
* Ignition Coil Pack: The 3.8L Windstar uses coil-on-plug ignition. A failing coil pack for cylinder 2 is a prime suspect. They can fail internally without obvious visual damage. Testing involves checking for proper resistance (using a multimeter) and potentially swapping it with another coil pack (from a different cylinder) to see if the misfire moves.
* Ignition Module (if applicable): Some Windstar years might use an ignition module (or control module) that distributes the signal to the individual coil packs. A fault here could affect a specific cylinder. This requires more advanced diagnostic tools.
* Distributor Cap and Rotor (if applicable): If your Windstar uses a distributor (less common on the 3.8L), inspect the cap and rotor for cracks, burns, or corrosion. These can cause poor signal transfer to the spark plugs.
3. Examine Fuel Delivery:
* Fuel Injector: A clogged or faulty fuel injector for cylinder 2 can prevent adequate fuel delivery, leading to a misfire. This often requires specialized tools like a fuel pressure gauge and injector testing equipment.
* Fuel Pressure: Low fuel pressure can affect all cylinders, but a weak pump might manifest more strongly in one cylinder.
4. Check Compression:
* Compression Test: A low compression reading in cylinder 2 indicates a problem with the engine's mechanical integrity, such as worn piston rings, a burnt valve, or a head gasket leak. This is a crucial test to rule out internal engine damage.
5. Investigate Vacuum Leaks:
* Vacuum System: A significant vacuum leak can disrupt the air-fuel mixture, especially affecting a specific cylinder. Inspect vacuum hoses and connections for cracks or damage.
6. Consider the PCM/ECM:
* Powertrain Control Module (PCM) or Engine Control Module (ECM): While less likely, a faulty PCM/ECM can cause misfires in a specific cylinder. Diagnosis requires advanced scan tools and potentially professional help.
Troubleshooting Steps:
1. Start with the easiest and cheapest: Re-check the spark plugs and wires for proper installation and condition.
2. Visual inspection: Thoroughly examine everything related to cylinder 2's ignition and fuel delivery system.
3. Use a multimeter: Check for resistance in the coil pack and other ignition components.
4. Swap components (where possible): Swapping the coil pack with another is a good way to isolate problems.
5. Advanced diagnostics: If the problem persists, use a scan tool to check for further trouble codes and data related to cylinder 2. A compression test is vital.
Important Note: If you're not comfortable performing these checks, especially those involving mechanical components or advanced diagnostic tools, take your Windstar to a qualified mechanic. Improper diagnosis or repair could lead to further engine damage.
