How to Access the Spark Plugs in a 2002 Ford Ranger

by Justin Cupler

The Ford Ranger has had its share of unorthodox spark plug replacement procedures in its lifespan. It began with the 2.3-liter engine used in the early 1990s that required eight spark plugs for its four cylinders. In more modern history, Ford chose to shoehorn a 4.0-liter engine into its Ranger, giving it a nice boost in power but proving a nightmare when replacing the plugs. It’s not the act of replacing the plugs, but gaining access to them that's the hardest part. The other two engines – a 3.0-liter V-6 and 2.3-liter four-cylinder – are rather straightforward.

Spark Plugs on a 2.3-Liter Engine

Step 1

Check the gap on all four new Motorcraft AGSF-32FEC or equivalent spark plugs with a spark plug gap tool. The required gap for the 2.3-liter engine is 0.041 to 0.045 inches. Exchange any incorrectly gapped spark plugs with new ones, as these plugs are not adjustable.

Step 2

Look down the center of the top part of the engine and find the four thick wires plugging into the engine – these are the spark plug wires. Grab the thick rubber boot on the engine end of one wire and pull upward with a twisting motion to remove it from the spark plug. Replace one plug at a time, so you don't mix up the wires.

Step 3

The spark plug is in the hole the spark plug wire was in. Remove it with a ratchet, 6-inch extension and spark plug socket. Remove the spark plug from the spark plug socket – a rubber insert holds it in the socket.

Step 4

Press a new spark plug into the spark plug socket until the rubber insert holds it in place. Connect the 6-inch extension to the socket and hand-thread the spark plug into the engine – feel for resistance as you thread the plug. Immediately remove the spark plug and start again if you feel any resistance.

Step 5

Connect a torque wrench to the extension and spark plug socket, and tighten the spark plug to 9 foot-pounds.

Step 6

Inspect the removed wire for defects, including burns, cracks, splits or excessive age. Replace all four spark plug wires one by one if any defects exist.

Step 7

Apply a small amount of dielectric grease meeting Ford specification ESE-M1C171-A into the spark plug wire boot and spread it around the inside of the boot with a small flat-head screwdriver.

Step 8

Line up the spark plug boot with the top of the spark plug and press the boot onto the spark plug until you feel it click into place.

Step 9

Repeat steps 2 through 8 to replace the remaining three spark plugs.

Spark Plugs on a 3.0-Liter Engine

Step 1

Check the gap on all six new Motorcraft AWSF-32PP or equivalent spark plugs with a spark plug gap tool. The 3.0-liter V-6 requires a gap from 0.042 to 0.046 inches. Exchange any spark plugs with the wrong gap for new ones, as you cannot gap these platinum-tipped plugs.

Step 2

Find the six thick spark plug wires routed down the sides of the engine, three on each side.

Step 3

Trace one spark plug wire toward the side of the engine until you reach the thick rubber boot on the end. Pull upward on the rubber boot with a slight twisting motion to expose the spark plug.

Step 4

Remove the spark plug with a ratchet and spark plug socket.

Step 5

Hand-thread a new spark plug into the engine and feel for resistance as you tighten it. If you feel resistance, remove the spark plug and start again. Torque the spark plug to 11 foot-pounds with a torque wrench and spark plug socket.

Step 6

Inspect the removed spark plug wire for defects – burn marks, splits, cracks or brittleness. If any defects exist, replace all six wires one by one. Replacing them in this manner helps retain the correct firing order.

Step 7

Squeeze a small amount of dielectric grease meeting Ford specification ESA-M1C171-A into the spark plug boot and spread it around with a small flat-head screwdriver.

Step 8

Align the spark plug boot with the top of the new spark plug and press the boot onto the spark plug until you feel it click onto the spark plug.

Step 9

Repeat steps 3 through 8 to replace the remaining five spark plugs.

Spark Plugs on a 4.0-Liter Engine

Step 1

Check the gap between the center and ground electrodes on all six new Motorcraft AGSF-34FP or equivalent spark plugs with a spark plug gap tool. The 4.0-liter requires a gap from 0.061 to 0.068 inches. These plugs have a non-adjustable gap, so exchange any incorrectly gapped plugs for new ones.

Step 2

Loosen the lug nuts on the right front wheel with a ratchet and socket, and raise the front of the pickup with a floor jack. Slide jack stands under the frame rails and lower the truck onto the jack stands. Remove the lug nuts and pull the right front wheel off the hub.

Step 3

Look inside the wheel well and find the plastic splashguard covering the side of the engine. Pry the five pin-style clips from the top of this splashguard with a flat-head screwdriver and remove the splashguard, exposing the three spark plug wires behind it.

Step 4

Trace one spark plug wire down to the thick rubber boot. Pull the boot upward with a slight twisting motion to remove it, exposing the spark plug below it.

Step 5

Remove the spark plug with a ratchet and spark plug socket.

Step 6

Hand-thread a new spark plug into the engine and feel for any resistance as you tighten it. If you feel resistance, remove the spark plug and start again. Tighten the spark plug to 13 foot-pounds with a torque wrench and socket.

Step 7

Inspect the entire spark plug wire for defects, like splits, cracks or brittleness. Replace all six spark plug wires one at a time if any defects exist. Replacing them one at a time negates the chance of mixing up the firing order.

Step 8

Apply a small amount of a dielectric grease meeting Ford specification ESE-M1C171-A into the inside of the spark plug boot, then spread the grease around inside the boot with a small flat-head screwdriver.

Step 9

Line up the spark plug wire boot with the top of the spark plug, then press it onto the spark plug until you fell it click onto the top of the plug.

Step 10

Repeat steps 4 through 9 to replace the remaining two spark plugs on the passenger’s side of the truck.

Step 11

Reinstall the splashguard inside the right front wheel well, and press the pin-style clips into the holes in the splashguard and wheel well to lock the splashguard into place.

Step 12

Reinstall the right front wheel onto the Ranger’s hub and snug the lug nuts. Raise the truck off the jack stands with a floor jack and remove the jack stands. Lower the truck to the ground and tighten the lug nuts – in a crisscross pattern – to 100 foot-pounds with a torque wrench and socket.