What is the Correct 99 Ranger 4.0 Firing Order Fix Misfires Now

The 1999 Ford Ranger equipped with the 4.0L Cologne V6 engine (engine code "X") uses the correct firing order: 1-4-2-5-3-6. Ensuring this firing order is strictly followed is crucial for eliminating misfires.

Essential Facts & Misfire Fixes

Cylinder Identification (Viewed from Driver's Seat):

• Front of Engine (Belt/Pulley Side)
• Passenger Side Bank (Even Cylinders): Cylinder #2 (Front) #4 (Middle) #6 (Rear)
• Driver Side Bank (Odd Cylinders): Cylinder #1 (Front) #3 (Middle) #5 (Rear)

Correct Wire Routing to Ignition Coils:

• The coil pack on this distributorless ignition system (DIS) typically has three coil towers.
• Top Coil Tower (Nearest Passenger Side): Fire Cylinders #1 (Front Driver Side) & #4 (Front Passenger Side).
• Middle Coil Tower: Fire Cylinders #2 (Front Passenger Side) & #5 (Rear Driver Side).
• Bottom Coil Tower (Nearest Driver Side/Intake): Fire Cylinders #3 (Rear Driver Side) & #6 (Rear Passenger Side).

Steps to Verify & Fix Misfires Related to Firing Order

1. Inspect Spark Plug Wires:
   • Carefully trace each wire from its spark plug back to the specific coil tower.
   • Ensure zero crossings or mix-ups, especially on the rear cylinders (#3 & #5 Driver side, #6 Passenger side).
   • Look for damaged insulation, burns (especially near exhaust manifolds), or loose connections. Replace damaged wires as a set.
2. Verify Plug Wire Seating:
   • Ensure both ends of every spark plug wire are firmly "clicked" onto the spark plug terminal and the coil tower nipple.
   • Rear plugs are hard to reach; mis-seated wire boots are a frequent cause of intermittent misfires.
3. Check Spark Plugs:
   • Remove plugs and inspect condition. Fouled, worn, or cracked plugs cause misfires.
   • Check gap and reset to specification (typically ~0.052 - 0.056 inches for stock application) or replace plugs if needed. Use recommended type (e.g., Motorcraft AGSF-22PP).
   • Ensure plugs are properly torqued (~13-15 lb-ft).
4. Test Ignition Coils:
   • A weak/failing coil can misfire even if wires and plugs are good.
   • Perform a resistance test across the coil pack terminals per repair manual specifications. Replace faulty coils.

Key Takeaway: Always start troubleshooting a misfire on the 4.0L Ranger by meticulously verifying the 1-4-2-5-3-6 firing order path and the condition of the spark plug wires, plugs, and coil pack connections before suspecting fuel injectors, compression, or PCM issues.