1. Ignition System (Most Likely Culprits):
* Spark Plugs & Wires: Start by inspecting the spark plugs and wires on the driver's side cylinders (cylinders 2 and 3, typically). Look for:
* Cracked or fouled spark plugs: Replace if necessary. Fouled plugs (covered in oil, carbon, or other deposits) prevent proper sparking.
* Damaged or loose spark plug wires: Check for cracks, fraying, or loose connections at both the plug and distributor cap. Replace damaged wires.
* Distributor Cap and Rotor: Inspect the distributor cap for cracks, carbon tracking (black streaks), or corrosion. The rotor should spin freely and be clean and undamaged. Replace if necessary.
* Ignition Coil: The coil provides the high voltage for sparking. A failing coil can cause misfires or complete lack of spark on one or more cylinders. Testing this requires a multimeter or a dedicated ignition coil tester.
* Ignition Module (or Electronic Ignition Control Unit - EICU): This component controls the ignition timing and spark delivery. A faulty module can cause intermittent or complete failure of spark. Testing usually requires a scan tool or a wiring diagram to check voltage and ground signals.
* Cranking System: Ensure the battery is fully charged and the starter motor is engaging properly. A weak battery or starter can result in low cranking speed, insufficient voltage for the ignition system, and subsequent misfires.
2. Fuel System:
* Fuel Injector(s): A clogged or malfunctioning fuel injector on cylinders 2 or 3 will prevent fuel delivery. A fuel pressure test is needed to check fuel pressure and injector operation. You might hear a clicking sound from a faulty injector.
* Fuel Pump: A weak or failing fuel pump may not deliver sufficient pressure to all cylinders. A fuel pressure gauge is essential for diagnosis.
* Fuel Filter: A clogged fuel filter can restrict fuel flow, affecting all cylinders but more noticeably on some due to fuel delivery order.
3. Engine Mechanical Issues:
* Valve Problems: Burnt or stuck valves on the driver's side cylinders would prevent combustion. This is less likely to only affect two cylinders simultaneously but is possible. A compression test would reveal this.
* Piston/Rings: Worn piston rings or damaged pistons can lead to low compression, preventing efficient combustion. A compression test is essential to diagnose this.
Troubleshooting Steps:
1. Visual Inspection: Start with a thorough visual inspection of the spark plugs, wires, distributor cap, and rotor.
2. Spark Test: If you have a spare spark plug, remove a plug wire, attach it to the spare plug, ground the plug to the engine block, and crank the engine. You should see a strong spark. Do this for each cylinder.
3. Fuel Pressure Test: This requires a fuel pressure gauge and is best done by a professional.
4. Compression Test: This will measure the compression in each cylinder. Low compression indicates mechanical issues.
Important Considerations:
* Safety First: Disconnect the negative battery terminal before working on the ignition system.
* Professional Help: If you're not comfortable performing these checks, it's best to take your Ranger to a qualified mechanic. Diagnosing electrical issues can be complex.
By systematically checking these areas, you should be able to narrow down the cause of your Ford Ranger's misfire. Remember to note any unusual sounds or smells during your inspection.
