1. The Basics - Check the Easy Stuff First:
* Spark Plug and Wire: Start with the simplest and most common cause. Remove the spark plug from cylinder #1, inspect it for damage (cracks, fouling, electrode wear), and replace it if necessary. While you're at it, carefully inspect the spark plug wire for cracks, damage, or loose connection at both the plug and distributor cap (if applicable - some 2.3L Rangers used a distributor, others a coil-on-plug system). A loose or damaged wire can prevent a good spark.
* Fuel Injector: A clogged or faulty injector can prevent fuel from reaching the cylinder. You can't easily test this at home without specialized tools but if you're comfortable, you can try swapping the injector with another cylinder (after carefully marking which injector goes where) to see if the misfire moves.
* Vacuum Leaks: Check all vacuum lines for cracks, holes, or loose connections. A significant leak can disrupt the engine's air/fuel mixture, leading to a misfire.
2. More Advanced Troubleshooting (May Require Tools):
* Compression Test: A low compression reading in cylinder #1 indicates problems with the valves, piston rings, or head gasket. This requires a compression tester.
* Spark Test: Using a spark tester, check for a strong, consistent spark at the spark plug wire for cylinder #1. A weak or intermittent spark points to issues with the ignition system (coil, ignition module, distributor cap/rotor if applicable).
* Fuel Pressure Test: Low fuel pressure can cause a misfire. This requires a fuel pressure gauge.
* Scanner/OBD-II Reader: Although a 1996 Ranger might not have a full OBD-II system, a basic code reader might pick up any trouble codes related to the misfire. This can provide clues to the problem area.
3. Potential Causes Based on the Symptoms:
* Worn Spark Plug: The most likely culprit.
* Faulty Ignition Coil (or Ignition Module): If the spark is weak or absent, the coil (or module in distributor systems) is suspect.
* Clogged Fuel Injector: Restricts fuel delivery.
* Vacuum Leak: Affects the air/fuel mixture.
* Low Compression: Indicates internal engine problems.
* Damaged Valve: Could prevent proper combustion.
* Burnt Valve: Similar to a damaged valve, prevents proper combustion
* Worn Piston Rings: Leads to low compression.
Important Note: Working on a vehicle's ignition system involves high voltage and can be dangerous. If you're not comfortable working with electricity or internal combustion engines, it's best to take your Ranger to a qualified mechanic. Attempting repairs without proper knowledge and tools can lead to further damage or injury.
