Ignition Coil Guide for the 1979-1986 Mazda RX-7
Keep your rotary engine firing on all cylinders by understanding its unique dual-coil ignition system.
- The 1979-1986 RX-7 uses two identical coils for its leading and trailing ignition; it's best to replace them in pairs.
- Original 'Diamond' brand coils are high quality, but reputable aftermarket brands like NGK and Standard are excellent alternatives.
- If using a universal canister-style coil, choose an epoxy-filled 'high vibration' model that can be mounted horizontally without leaking.
- Replacement is a simple DIY job that takes less than an hour with basic tools.
Symptoms of a Failing Ignition Coil
A bad ignition coil in your first-generation RX-7 can cause noticeable running problems. Because the car has two coils, symptoms can sometimes be confusing, but they typically point to a lack of spark. Watch for these common signs:
- Engine Misfires: The engine may stumble, shake, or hesitate during acceleration. This happens when a cylinder fails to fire correctly due to weak or no spark.
- Hard Starting or No Start: If a coil fails completely, the engine may be very difficult to start or may not start at all.
- Rough Idle: The engine may vibrate or sound uneven when the car is stopped.
- Loss of Power: Your RX-7 may feel sluggish and less responsive, especially at higher RPMs.
- Poor Fuel Economy: When combustion is incomplete, the engine uses more fuel to do the same amount of work.
Choosing the Right Aftermarket Ignition Coil
When replacing ignition coils on a first-generation RX-7, you have a choice between OEM and a wide range of aftermarket brands. While many owners prefer the original Diamond-brand OEM coils for their proven quality, they can be hard to find and expensive. Good aftermarket coils offer a reliable and affordable alternative.
Pro Tip: The 1979 models used ignition points, while 1980 and newer models have an electronic distributor. Ensure the coil you buy is compatible with your specific year, as some coils require an external resistor and others do not.
Brand Quality Tiers
Not all aftermarket brands are created equal. Here’s a general breakdown of the brands available for your RX-7:
- Premium Aftermarket (NGK, Standard Motor Products): Brands like NGK and Standard (SMP) have a strong reputation among RX-7 owners and mechanics. They use high-quality materials like pure copper windings and robust insulation designed to meet or exceed original specifications. These are often considered the most reliable aftermarket choices.
- Standard Aftermarket (Delphi, Spectra, Walker): These brands provide a good balance of quality and value. Delphi is a well-known OE supplier for many manufacturers, and their aftermarket parts are generally dependable. Spectra and Walker also produce reliable ignition components that serve as a solid replacement for a daily driver.
- Economy Aftermarket (Global Parts, Holstein, Skyward): These brands offer the most budget-friendly options. While they can get your car back on the road, their long-term durability and performance may not match that of premium brands. They are a viable choice if the budget is the primary concern.
Important Note on Oil-Filled Coils: Many universal canister-style coils are filled with oil for cooling and insulation. The RX-7 mounts its coils horizontally. If you use a standard oil-filled coil, it can leak over time and fail. When choosing a canister-style coil, make sure it is an epoxy-filled or 'high-vibration' model designed to be mounted in any position.
Replacement Cost
The cost to replace ignition coils on a 1979-1986 RX-7 is relatively low, especially if you do the work yourself. The parts are affordable and easy to access. Below are typical cost ranges.
| Part Type | Cost Range (Per Coil) |
|---|---|
| New Aftermarket | $29.97 - $57.74 |
| New OEM (Mazda) | $70 - $90 |
| Shop Labor | $75 - $100 |
Frequently Asked Questions (FAQ)
Do I need to replace both ignition coils at the same time?
It is highly recommended. The coils are the same age and have been exposed to the same conditions. If one has failed, the other is likely not far behind. Replacing them in pairs ensures the ignition system is balanced and reliable.
What is the difference between a leading and trailing coil?
For the 1979-1985 models, the leading and trailing coils are typically the same part, just used in different positions for the two stages of ignition. The leading coil fires first to start combustion, and the trailing coil fires second to complete it. Always verify the part numbers for your specific year.
Is replacing an RX-7 ignition coil a difficult job?
No, this is a very DIY-friendly job. The coils are mounted on the driver's side of the engine bay and are easily accessible. The replacement involves disconnecting the battery, unplugging the electrical connectors and spark plug wires, and unbolting the coil from its bracket. The job can usually be done in under an hour with basic hand tools.
Are there any recalls or TSBs for the ignition coils on my RX-7?
There are no active NHTSA recalls for ignition coils on the 1979-1986 Mazda RX-7. Given the age of the vehicle, any Technical Service Bulletins (TSBs) that may have existed are now obsolete and repairs are based on general mechanic knowledge.
Technical Specifications
OEM Part Numbers: 1480-18-100 8245-18-100
System Type: Dual coil, distributor-based ignition (Points for 1979, Electronic for 1980-1986). Coils Required: 2. Mounting: Horizontal.
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The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.