NGK Iridium Premium Spark Plug Set (x4) – MX-5 MK3 / NC 1.8L (2005–2015) • TR5AI-13

NGK Iridium Premium Spark Plug Set (x4) – TR5AI-13

Complete NGK iridium spark plug service set for Mazda MX-5 MK3 / NC, MK3.5 / NC2 and MK3.75 / NC3 1.8L MZR petrol engines (2005–2015). Supplied by MazSpec as a complete set of four spark plugs, providing the correct quantity for all four cylinders.

NGK TR5AI-13 is a premium iridium spark plug designed for reliable ignition performance, consistent combustion and long service life in compatible Mazda petrol engines.

Spark plugs ignite the compressed air and fuel mixture within each cylinder. As spark plugs age, electrode wear and deposits can contribute to misfires, difficult starting, rough running and reduced engine efficiency.

These NGK spark plugs feature an iridium centre electrode, chosen for its durability and ability to maintain dependable ignition characteristics throughout the plug's service life. The design also incorporates a copper-core electrode construction for effective heat transfer, a ceramic insulator and a resistor to help suppress electrical interference.

MazSpec supplies this product as a complete four-plug set, making it a convenient option for routine engine servicing, scheduled ignition maintenance and replacement of worn or damaged spark plugs.

Product features and specifications:

• Product type: Iridium ignition spark plug set
• Brand: NGK
• Manufacturer part number: TR5AI-13
• NGK stock number: 90813
• Centre electrode: Iridium
• NGK heat range: 5
• Thread diameter: M14
• Thread pitch: 1.25mm
• Thread reach: 17.5mm
• Socket / hex size: 16mm
• Electrode gap: 1.3mm
• Seat type: Tapered
• Ground electrodes: 1
• Resistor: 5 kOhm
• Terminal type: Fixed SAE connector
• Engine application: Mazda MZR L8 1.8L petrol
• Vehicle application: Mazda MX-5 MK3 / NC 1.8L
• Quantity supplied: 4 spark plugs
• Quantity required per engine: 4 spark plugs
• Country of origin: Japan

Why Choose Iridium Spark Plugs? Iridium is a highly durable electrode material, helping the spark plug maintain its ignition characteristics over extended service intervals. NGK iridium spark plugs provide dependable performance for vehicles requiring their specified electrode design, heat range and dimensions.

Common replacement reasons: Worn spark plugs can contribute to difficult starting, intermittent misfires, uneven idle, reduced fuel economy and poor engine response. Replacing all four plugs together helps maintain consistent ignition performance across the engine.

Fitment advice: Designed for Mazda MX-5 MK3 / NC 1.8L MZR engines using the NGK TR5AI-13 spark plug specification. Not suitable for the MX-5 MK3 2.0L engine, which uses a different spark plug specification and thread reach. These plugs feature a 17.5mm reach and tapered seating arrangement.

Other items to consider: When completing an engine service, you may also want to purchase engine oil, an oil filter, air filter, ignition coil components or a complete MazSpec service kit.

Useful tools / consumables: 16mm spark plug socket, socket extension, calibrated torque wrench and suitable cleaning equipment for removing debris from the spark plug wells.

Difficulty guide: DIY Difficulty: Easy to Moderate. Spark plug replacement is a routine servicing operation, but correct installation is important to avoid damage to the aluminium cylinder head threads or ignition components.

Why NGK? NGK is a leading manufacturer of ignition components, supplying spark plugs for original-equipment and aftermarket applications. Its iridium spark plug range combines precision engineering, advanced electrode materials and vehicle-specific specifications for dependable ignition performance.

What's in the box: 4 × NGK TR5AI-13 Iridium Spark Plugs (NGK stock number 90813), comprising one complete four-cylinder engine service set.

Installation / service notes: Allow the engine to cool before removing the existing spark plugs. Carefully disconnect the ignition coils and clean around the plug wells to prevent dirt entering the combustion chambers. Remove the old spark plugs using a suitable socket and inspect the replacement plugs before installation. Avoid altering the factory electrode gap unless specifically instructed by NGK. Start each plug by hand to prevent cross-threading and tighten using the appropriate vehicle or NGK specification for the tapered seat. Refit the ignition coils and electrical connectors securely, then start the engine and confirm smooth operation.