How to Tune-Up your Land Rover LR3/LR4 by replacing the Spark Plugs

For your vehicle, spark plugs are the small-but-mighty catalysts that set everything in motion. As the name suggests, a spark plug discharges a spark of electricity across a small gap to ignite the combustion of the fuel-air mixture needed to start your car’s engine and keep it running.

The combustion pushes the piston which in turn drives the crankshaft and thus keeps the engine rotating at high speed.

Why you need to change worn spark plugs

Spark plugs are designed to survive the super-hot environment of the combustion they initiated. Nevertheless, spark plugs, like everything else, will wear out with time. Or rather, burn up with time. Because, as the sparks jump across the two electrodes, they burn off tiny amounts of metal. With time, the gap increases so much that the sparks struggle to cross or even fail. That is when the jerking, poor gas mileage and hard starting starts to show up.

Without spark plugs, your car engine will never come to life. And old and worn spark plugs will directly affect the performance of your Land Rover LR3's engine. Some of the signs of weak and bad spark plug include difficulty in starting, engine misfiring while accelerating, poor fuel economy, etc. Therefore, tune-up maintenance on your LR3 or LR4 which involves the replacement of weak spark plugs will inject fresh vigor into your ride and have the engine performing at optimal power and economy.

Spark plug replacement: is it something you can do yourself?

The ease of accessing the spark plugs on engines vary fom car to car. Some vehicle models are notoriously difficult to try to replace the spark plugs yourself. It often requires the removal of most of the intake manifold and other parts before the spark plugs can be assessed.

Fortunately, the LR3 and LR4 have got engine configurations with relatively easy access to their spark plugs. The Spark plugs are located close to the top of the engine. Each cylinder has a spark plug in it. Thus your LR3 or LR4 which is equipped with a V8 engine will have eight spark plugs.

And the good news is, you can easily replace all eight spark plugs on your LR3 all by yourself. It’s not every car issue that you should take to your mechanic. With some knowledge and a few tools (and sometimes a bruised knuckle), you can tackle so many car issues yourself, save a few hundred bucks and maybe shed some weight while you are it. Replacing your spark plugs is one of the easiest maintenance activities you can carry out on your vehicle. So, if you’ve got some time on your hand, pop up the hood of your LR3 and get started.

You’ll need a 5/8 spark plug socket, a ratchet, extensions of varying lengths, flat screwdriver,torque wrench and an 8mm wrench.

Here’s the step-by-step guide:

1. 1. Take off the plastic engine cover. Unscrew the four bolts that secures the engine cover. Then remove the engine oil cap to allow the engine cover to come off.
2. 2. Pry out the plastic panels covering the ignition coils on top of the engine block. The exposed ignition coils are neatly arranged - 4 on each side. Each coil is held down with an 8mm bolt.
3. 3. Unplug the ignition coil electrical connector (wire harness).Depress the locking tab and wiggle the connector of the coil.
4. 4. Remove the 8mm coil hold-down bolt. Use a wrench or an 8mm socket
5. 5. Pull out the ignition coil. With the bolt removed, you can then pull out the entire ignition coil and boot assembly. The hole is rather deep and at its end lies the spark plug.
6. 6. Remove the spark plug. Drop the 5/8 spark plug socket into the hole and using an extension attached to a ratchet, unscrew the spark plug (by turning it anti-clockwise). The spark plug socket has rubber lining on the inside to hold the plugs snugly in place so you can pull them out.
7. 7. Inspect the spark plug, ignition coil, and chamber walls for any sign of dirt or oil. Any dirt or oil could signify a worn ignition boot and may cause significant issues with time. If there is any oil or dirt, it means you’ll have to change the ignition coil boot.
8. 8. Put the new spark plugs into the 5/8 spark plug socket and guide it down the hole till it's well placed. Mind you, you don’t have to gap the plug. Most modern spark plugs come pre-gapped.
9. 9. Using the extension and the ratchet, gently screw the spark plug inside. Ensure you don’t overtighten it, so you don’t damage the spark plug or the engine block. For that, I’ll recommend a torque wrench. However, if you cant lay your hands on one, check your Land Rovers owner’s manual for the right technique to apply just the right torque.
10. 10. Put back the ignition coil. Slide the ignition coil back in till it firmly connects with the end of the newly mounted spark plug. Then plug in the wire harness and secure the ignition coil in place with the 8mm bolt.

Now, repeat the process for the other spark plugs. Ensure you carry out the step 3 to step 9 for each cylinder before you move on to the next. This helps you avoid mixing up the ignition coils and wire harnesses. A mix-up in the firing order could damage your engine.

As you can see, changing the spark plug is relatively easy, and you will be done in no time. However, you may have some difficulty in accessing the ignition coil and then the spark plug for cylinder number one. You can get to it by removing the air tubing that connects the air filter to the throttle body.

When you are done replacing the spark plugs, cover the ignition coil panel and replace the plastic engine cover. Screw on the engine oil cover.

Now start up the engine and take the truck for a spin. The new-found responsiveness and efficiency will amaze you.