1. Verify the Replacement Parts:
* Correct Parts: Double-check that you installed the *correct* spark plug and coil pack for your engine. Using the wrong parts will cause problems. The part numbers should match what your vehicle's specifications call for.
* Installation: Ensure both the spark plug and coil pack are correctly installed and seated. A loose connection or improperly gapped spark plug can cause misfires. Consult a repair manual for precise installation instructions.
2. Diagnostic Steps:
* Retrieve Diagnostic Trouble Codes (DTCs): You'll need a scan tool (OBD-II reader) to retrieve the specific trouble codes. The "P0306" code (cylinder 6 misfire) is expected, but there might be *other* codes that point to the root cause. Auto parts stores often offer free code reading.
* Inspect Wiring and Connections: Carefully examine the wiring harness leading to the cylinder #6 spark plug and coil pack. Look for:
* Broken or frayed wires: Repair or replace any damaged wiring.
* Corrosion or loose connections: Clean connectors and ensure tight connections.
* Damaged connectors: Replace any damaged connectors.
* Inspect the Injector: A faulty injector on cylinder #6 can also cause a misfire. You might need to test the injector's operation using a multimeter or a specialized injector tester.
* Compression Test: Perform a compression test on cylinder #6. Low compression indicates a problem with the valves, piston rings, or head gasket.
* Visual Inspection: Look for any obvious signs of damage to the cylinder head, such as cracks or warping.
3. Potential Causes (Beyond Spark Plug/Coil):
* Faulty Fuel Injector: The injector might be clogged, leaking, or electrically faulty.
* Low Fuel Pressure: A problem with the fuel pump or fuel pressure regulator can starve the engine of fuel.
* Vacuum Leaks: Leaks in the intake manifold or vacuum lines can affect engine performance and cause misfires.
* Camshaft or Crankshaft Sensor Issues: Problems with these sensors can disrupt ignition timing and lead to misfires.
* Internal Engine Damage: Severe problems like a bent valve or a cracked piston could be the underlying issue. This is less likely if you recently replaced the spark plug and coil pack.
4. Seeking Professional Help:
If you're not comfortable performing these diagnostic steps yourself, it's best to take your Escape to a qualified mechanic. They have the tools and expertise to properly diagnose and repair the problem. Continuing to drive the vehicle with a misfire can cause further damage.
Important Note: Ignoring a persistent check engine light can lead to more serious engine damage. Address this issue as soon as possible.
