How to Increase the Fuel Mileage of a 4.0 Liter Ford Rangerby John WalkerUpdated November 07, 2017
Items you will need
Split-platinum or iridium plugs
High-flow air filter
Spark plug socket
The Ford Ranger 4.0L six-cylinder engine gets approximately 15 to 21 mpg on the models fresh off the factory floor. Older versions of the same engine will have slightly lower mileage due to wear and tear on the engine. The mileage is fairly typical of most six-cylinder engines. Improving the mileage without paying high prices requires adding a high-flow air filter to increase the air intake and split-platinum or iridium spark plugs to improve the consistency and quality of the spark. Replacing the plugs and the air filter takes about 30 minutes.
Replace the air filter with a high-flow, lifetime air filter. The air filter housing, located on the front, passenger-side of the engine compartment, opens by releasing the four retaining clamps on the left and right sides. Lift the housing cover up and remove the old air filter. The high-flow filter is the same size and shape as the original. Insert the new filter and replace the housing cap. Press the four retaining clamps into place.
Pull the spark plug wire off of the first spark plug and position it to the side. Insert the spark plug socket and socket wrench into the spark plug hole until the socket grasps the spark plug. Rotate the plug counterclockwise to remove. Insert the new plug into the socket and press the plug into place. Twist the plug clockwise to tighten it. Press the spark plug wire onto the spark plug until you feel it click into place. Repeat for the remaining plugs. Work on one plug at a time to avoid mixing up the spark plug wires.
Take the vehicle to a muffler shop to have the stock exhaust pipe and muffler replaced with a larger, high-flow system. The costs of the system are slightly elevated compared to air filter and spark plug changes. Replacing the stock exhaust pipe will allow the vehicle to release exhaust gases easier creating a lower consumption of fuel. The muffler shop can also replace the stock exhaust manifold with a high-flow model for a substantial cost.