Things you can (relatively easily) check yourself:
* Spark Plugs and Wires: These are the most frequent culprits. Inspect the spark plugs for wear, fouling (black, white, or oily deposits), cracks, or incorrect gap. Also, visually inspect the spark plug wires for cracks, damage, or loose connections. If they look suspect, replace them. This is a relatively inexpensive fix.
* Ignition Coil(s): The ignition coil(s) supply the high voltage to the spark plugs. A faulty coil will cause a misfire in the cylinder(s) it controls. You might be able to visually inspect for obvious damage, but testing usually requires a multimeter or a professional scan tool.
* Fuel Injector: A clogged or faulty fuel injector can prevent sufficient fuel from reaching the cylinder. This requires more specialized tools to test (fuel pressure gauge, injector tester) or a professional diagnosis.
Things that require more advanced tools or professional help:
* Mass Airflow Sensor (MAF): A faulty MAF sensor provides inaccurate air flow readings to the engine computer, leading to improper fuel mixture and misfires. Requires a scan tool to check for error codes.
* Engine Control Module (ECM): The ECM controls many aspects of the engine's operation. A faulty ECM can cause misfires, but this is less common. Diagnosis requires a sophisticated scan tool.
* Camshaft Position Sensor (CMP) or Crankshaft Position Sensor (CKP): These sensors tell the ECM the position of the crankshaft and camshaft, crucial for proper ignition timing. A faulty sensor can cause misfires. Requires a scan tool to diagnose.
* Vacuum Leaks: A leak in the vacuum system can disrupt the air/fuel mixture. This requires careful inspection of all vacuum hoses and connections.
* Compression Test: This checks the pressure within the cylinder. Low compression in one cylinder indicates a problem with the piston rings, valves, or head gasket.
Before you start:
1. Check for error codes: Use an OBD-II scanner (available relatively inexpensively at auto parts stores) to read any diagnostic trouble codes (DTCs) stored in your vehicle's computer. These codes can pinpoint the likely source of the misfire.
2. Identify the misfiring cylinder: Some scanners can tell you which cylinder is misfiring. If not, a mechanic can use a scan tool or other methods to pinpoint it.
Recommendation: Unless you're comfortable working on cars and have the necessary tools, it's best to take your Taurus to a qualified mechanic for diagnosis and repair. Ignoring a misfire can lead to more serious engine damage. The cost of a proper diagnosis is usually far less than the potential cost of extensive engine repair down the road.
