X4XZ Ignition Coil & Double-Iridium Spark Plug Kit — 6-Pack for Nissan/Infiniti 3.5L, OEM-fit, reduces misfires

This X4XZ kit bundles six UF550 ignition coils with six 1406 double iridium spark plugs to provide an OEM-fit replacement for many Nissan and Infiniti 3.5L vehicles. Each component is built to match or exceed original equipment standards so you can restore dependable ignition, reduce misfires, and maintain efficient combustion without custom modifications.

Which vehicles are these coils and plugs compatible with?

The set is designed specifically for a wide range of Infiniti and Nissan gasoline models that use the UF550 coil and 1406 plug OE numbers. Always compare part numbers and the visual appearance of the coil and plug with your current units before ordering.

• Infiniti coverage includes EX35, FX35, G25/G35, JX35, M35/M35h, Q50, Q70, and QX60 model years listed in the product features.
• Nissan coverage includes 350Z, Altima, Maxima, Murano, Pathfinder, and Quest model years listed in the product features.
• Replaces OE: C1670, 22448-JA10C, 5C1727 — check connector style and plug gap to confirm fit.

How do these parts improve engine performance and reliability?

New coils and double-iridium plugs restore consistent spark delivery, which helps reduce misfires, smooth idle, and recover lost power. The combination is aimed at returning factory ignition timing characteristics and preserving fuel efficiency under normal driving conditions.

• Double iridium electrodes offer longer life and steady spark energy over extended mileage (manufacturer-rated life up to 100,000 km).
• Premium coil materials, stainless-steel spring, and internal ferrite noise suppression reduce radio interference and improve electrical transfer.
• Thermoplastic coil connector resists heat cycling and maintains a secure plug connection for consistent ignition.

What should I expect during installation and maintenance?

Installation follows the same steps as the original parts — remove the old coils and spark plugs, inspect the cylinder head, and install the new plugs and coils to torque specifications. No special tools beyond a spark plug socket and torque wrench are required, but an experienced DIYer or technician is recommended for correct gap and torque settings.

• Package includes: 6 ignition coils and 6 double iridium spark plugs; no printed manual included.
• Inspect boot seals and coil connectors for fit; torque plugs to manufacturer spec and route coil harness correctly.
• If symptoms persist after install, verify ECM codes and wiring circuits before replacing additional parts.

Who is this for: This X4XZ UF550 + 1406 kit is aimed at owners and mechanics servicing Nissan and Infiniti 3.5L engines who need a full-bank coil-and-plug replacement. It suits drivers restoring engine smoothness and reliability after age- or mileage-related ignition wear, and professionals seeking a ready-made six-cylinder replacement pack for timely repairs.