When to Change Spark Plugs During an Ignition Coil Pack Replacement
When considering the maintenance of your vehicle's ignition system, one common question arises: should you change spark plugs when replacing ignition coil packs?
Before we delve into the details, it is essential to refer to your Vehicle Manufacturer's Original Equipment Maintenance (OEM) schedule. This schedule will provide a suggested replacement interval and troubleshooting guidance, such as checking for corrosion at wire connectors or heat cracks in the coil bodies.
Consulting your owner's manual and local dealership is also advisable for specific guidance. They can provide detailed insights into the components' current state and necessary replacements.
Is It Necessary to Change the Spark Plugs?
When changing ignition coil packs, the decision to replace the spark plugs depends on their condition and mileage. If the spark plugs have been in use for over 50,000 miles, it is often recommended to replace them even if not strictly necessary. This is because worn or malfunctioned spark plugs can contribute to issues with the ignition coil packs.
While it may seem like a minor expense, changing the spark plugs during this maintenance window is a good practice. It ensures that you do not encounter issues down the line, such as intermittent misfires or poor engine performance.
Common Issues Caused by Failed Spark Plugs
Failing spark plugs can often be a contributing factor to the need for new ignition coil packs. This is because the plugs play a crucial role in igniting the fuel-air mixture. If they are not functioning properly, it can lead to a misfiring engine, which in turn damages the ignition coils.
Regular maintenance is always recommended, as it can prevent more significant and costly repairs in the future. Ignoring worn spark plugs can result in a decline in engine performance, increased fuel consumption, and even potential engine damage.
Coil-On-Plug Ignition Systems and Specific Case Studies
Coil-on-plug (COP) ignition systems, where each spark plug has its own ignition coil, require particular attention. In these systems, if one ignition coil fails, the corresponding spark plug is likely to have undue stress, leading to premature wear and failure.
For instance, my brother performed a complete ignition system overhaul on a friend's Ford BF Falcon, a car with a DOHC 4-liter in-line six-cylinder engine. The car used pencil-type Motorcraft ignition coils, known for their failure rate after 100,000 kilometers (60,000 miles). Four out of six ignition coils failed at 80,000 kilometers (48,000 miles), necessitating the replacement of both the ignition coils and spark plugs.
Despite improvements, the Ford EF Falcons continued to experience significant issues with ignition coil packs. This led Ford to revert to a Thick Film Ignition (TFI) system in the next model, the EL Falcon. However, the series 1 AU Falcon continued to face similar problems, leading to design changes in later models.
Given this history, it seems prudent to replace all ignition coils and spark plugs when one of them fails, especially when working on a COP system.
Conclusion and Additional Considerations
Although not always necessary, replacing spark plugs during an ignition coil pack replacement is a wise choice. It ensures that your vehicle continues to run efficiently and reliably. With COP ignition systems, if a single coil is difficult to access, replacing the entire bank along with the spark plugs is often the best approach.
Keeping up with regular maintenance and being mindful of the specific components and their manufacturing history can significantly extend the life of your vehicle and prevent costly repairs in the long run.