First off, your Scion iM engine won't run without spark plugs - it won't even turn on without them. So, in that sense, you have no choice but to use spark plugs. However, beyond that, the proper Scion iM spark plugs can improve performance and fuel economy, especially if your current spark plugs have been in use for a while. Some people change their Scion iM spark plugs at every oil change, some change them annually, and some go by a specified mileage interval. Whatever your preferred schedule, you should inspect the plugs as often as possible, especially if you are experiencing hesitation or missing, or after you have made modifications to your engine.

Spark plugs convert your Scion iM engine's air/fuel mixture into energy by igniting it in the combustion chamber, making them one of the most important components in your ignition system, not to mention your engine itself. As critical as they are, it seems that they are neglected far too often and aren't given enough consideration when making performance modifications. Choosing the proper heat range for your Scion iM spark plugs is just as important as making sure that the plugs are gapped correctly, so keep this in mind when choosing plugs for your stock or modified Scion iM engine.

Q: How do you install spark plugs?
A: Spark plugs are installed by using a spark plug socket. Simply remove the spark plug wires and unbolt the plugs. Replace and gap the new plugs and you should be set.

Q: What are spark plugs? Why buy spark plugs?
A: Spark plugs create a spark in the combustion chamber of the engine, igniting the fuel and air mixture and getting the engine running. When you're running a higher horsepower motor, spark plugs play a big role. A colder heat range plug (which is what more aftermarket spark plugs are) has less insulation; it cools off faster between firing and the introduction of a fresh charge of the air/fuel mixture. A hot plug can ignite the air/fuel mixture before the plug actually fires. This is called pre-ignition, a form of detonation, and can destroy a motor. When upgrading the power of your vehicle, make sure to look into a colder range spark plug.

Q: Do spark plugs come in sets of 4?
A: Spark plugs are sold individually (unless otherwise noted) and should be replaced all at the same time.