How to Change the Spark Plugs in a '94 Trooper

The Isuzu Trooper was introduced in 1981. The 1994 Trooper was equipped with a 3.2-liter MFI V-6 engine, capable of producing 175 horsepower and 188 foot-pounds of torque. The 1994 Trooper was available in two- and four-door models, with two- or four-wheel-drive. The spark plugs on the 1994 Trooper are inside the valve covers or rocker covers of the engine. Accessing the spark plugs is somewhat easy, but special care must be taken when removing and installing these spark plugs.

Instructions

1

Open the Trooper's hood and set the hood prop. Remove the negative battery cable from the battery using a 3/8-inch-drive ratchet and socket.

2

Remove the air filter housing lid from the filter housing. Loosen the hose clamp for the air intake duct to the throttle body on the engine, using a ratchet and socket. Pull the small vacuum tube free from the track in the top of the intake air duct. Remove the second vacuum hose from the middle of the duct on the engine side of the hose, by hand. Remove the air intake duct completely.

3

Remove one of the spark plug wires by pulling the boot upward and out of the valve cover. Twist the boot as you pull it upward to ease removal from the spark plug. Inspect the plug wire from the engine to the forward mounted coil pack, on the upper front of the engine. If you find burn marks, tears or missing wire sheathing, replace the spark plug wire.

4

Remove the spark plug from the engine using a ratchet, extension and spark plug socket. Spark plug sockets are specially designed to grab spark plugs. This is very important, because if the spark plug falls inside the valve cover during removal or installation, the entire valve cover has to be removed. Turn the spark plug counterclockwise with the ratchet, making sure you have a good grip on the plug with the socket. Pull the plug out, trying not to hit the sides of the valve cover hole.

5

Inspect the spark plug gap on all of your new spark plugs, using a wire spark plug gap gauge. Adjust the ground electrode or arc on the plug to adjust the gap, using the electrode tool on the gauge. Spark plugs made of higher-grade materials such as iridium cannot be adjusted. Take these types of plugs back and get spark plugs with the matching spark plug gap specifications for this truck. The 1994 Isuzu Trooper spark plug gap should be between 0.040 and 0.043 inches.

6

Separate the extension and socket from your ratchet. Insert your new spark plug into the spark plug socket and press it firmly into the rubber boot in the socket. Insert the spark plug into the engine and tighten it snug by hand to ensure proper threading.

7

Install a 1/2-inch-drive to 3/8-inch-drive adapter on the end of a 1/2-inch extension. Install the combination of tools onto a 1/2-inch-drive torque wrench. Insert the spark plug socket onto the other end of the setup. Tighten the spark plug to 14 foot-pounds. Insert dielectric grease into the spark plug mounting hole in the spark plug wire. Install the spark plug wire onto the plug and push it downward until it pops into place. Gently tug on the spark plug wire boot to ensure a good grip between the plug and wire.

8

Repeat steps 3 through 7 to replace the rest of the spark plugs. Connect the air intake duct onto the throttle body, then install the air filter housing hood. Tighten the intake duct clamp snug to the throttle body with a ratchet and socket. Install the vacuum tube into the engine side of the duct, then attach the other vacuum tube to the top of the intake duct.

9

Install the negative battery cable and tighten it snug with a ratchet and socket.