NGK LFR6AIX-11 6619 Iridium IX Spark Plugs – Pack of 6 | OEM Replacement

NGK LFR6AIX-11 6619 Iridium IX Spark Plugs – Pack of 6 | OEM Replacement

$57.99
$57.99 $67.99
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NGK LFR6AIX-11 6619 Iridium IX Spark Plugs – Pack of 6 | OEM Replacement
  • NGK LFR6AIX-11 6619 Iridium IX Spark Plugs – Pack of 6 | OEM Replacement
  • NGK LFR6AIX-11 6619 Iridium IX Spark Plugs – Pack of 6 | OEM Replacement
  • NGK LFR6AIX-11 6619 Iridium IX Spark Plugs – Pack of 6 | OEM Replacement
  • NGK LFR6AIX-11 6619 Iridium IX Spark Plugs – Pack of 6 | OEM Replacement
NGK LFR6AIX-11 6619 Iridium IX Spark Plugs – Pack of 6 | OEM Replacement

NGK LFR6AIX-11 6619 Iridium IX Spark Plugs – Pack of 6 | OEM Replacement

$57.99
$57.99 $67.99

Upgrade your ignition performance with the NGK LFR6AIX-11 6619 Iridium IX Spark Plug Pack of 6. Designed with advanced iridium technology, these spark plugs deliver superior durability, consistent firing, and improved throttle response for your engine.


Features & Benefits

  • ✅ OEM-quality NGK spark plugs for guaranteed fit and reliability
  • ✅ Fine iridium tip ensures long life and high performance
  • ✅ Provides faster starts, smooth idling, and better fuel efficiency
  • ✅ Resistant to fouling and wear for long-lasting use
  • ✅ Trusted by professional mechanics and enthusiasts worldwide


Vehicle Compatibility

The NGK LFR6AIX-11 6619 spark plugs are commonly compatible with a wide range of vehicles, including but not limited to:

  • Nissan 350Z, Altima, Maxima, Murano
  • Infiniti G35, FX35
  • Subaru WRX, Forester, Legacy (select models)
  • Mitsubishi Lancer Evolution, Outlander

(Please check your vehicle owner’s manual or OEM part number for exact fitment.)


Cross Reference

  • Denso 5344 (IK16)
  • Champion REC10WMPB4
  • Autolite XP3923
  • Bosch 4417

(Verify with manufacturer before ordering.)


What’s Included

  • 6 × Genuine NGK LFR6AIX-11 6619 Iridium IX Spark Plugs


Why Buy From Us

  • 🔧 100% Genuine NGK Products
  • 🚗 Perfect fit for OEM replacement
  • 🚀 Fast USA Shipping & Easy Returns
  • ✅ Trusted Auto Parts Supplier

❓ FAQ

Q: What makes the iridium construction of the NGK LFR6AIX-11 superior to standard copper or platinum spark plugs?

A: The core advantage lies in the melting point and hardness of the metal. Iridium is one of the world's rarest precious metals, boasting an incredibly high melting point of approximately 2400°C (far higher than platinum or copper). This extreme thermal resistance allows NGK to engineer an ultra-fine center electrode tip measuring just 0.6mm in diameter.

A smaller electrode tip requires significantly less electrical voltage to spark across the gap. This results in a more concentrated, hotter spark kernel that ignites the air-fuel mixture faster and more completely. For the driver, this translates into quicker cold starts, crisper throttle response, and maximum resistance to spark plug fouling under high-load driving conditions. While traditional copper plugs wear out after 30,000 miles, these Iridium IX plugs easily maintain gap integrity for 40,000 to 50,000 miles.

Q: What does the specific part number code "LFR6AIX-11" break down to in terms of thread size, heat range, and factory gap?

A: NGK part numbers are highly specific technical blueprints. Breaking down LFR6AIX-11 (Stock Number 6619) reveals the exact physical layout of the plug:

  • LF: Indicates a 14mm thread diameter paired with a long 26.5mm (1.04 inches) reach design, commonly used in deep-well dual overhead cam (DOHC) cylinder heads.

  • R: Signifies an internal resistor type plug, which suppresses electromagnetic radio frequency interference (RFI) that could disrupt your vehicle's sensitive ECU, audio systems, or sensor signals.

  • 6: Represents the NGK Heat Range. NGK uses a scale where lower numbers are hotter and higher numbers are colder. A 6 is a versatile, mid-range standard heat rating perfect for factory-spec naturally aspirated and mild turbocharged street engines.

  • A: Internal design construction feature.

  • IX: Designates the premium Iridium IX performance style.

  • -11: Specifies a pre-set factory gap of 1.1mm (0.044 inches), optimized for the high-energy coil-on-plug ignition systems found in Nissan, Infiniti, and Subaru platforms.

Q: What are the exact step-by-step instructions for installing these spark plugs, and why must you be incredibly careful when gapping iridium tips?

A: Changing spark plugs on modern DOHC engines requires absolute cleanliness, precision torque to protect aluminum cylinder head threads, and delicate handling of the precious-metal electrodes:

1.Disconnect the ignition coil packs and clean the area:Allow the engine to cool completely to avoid stripping aluminum threads.

Park the vehicle on level ground and disconnect the negative battery terminal. Remove any plastic engine beauty covers. Locate the individual coil-on-plug units. Unplug the electrical wiring harness from the coil pack by depressing the locking tab, remove the retaining bolt (usually 10mm), and pull the coil straight up out of the spark plug well with a slight twisting motion. Use compressed air to blow any debris out of the deep well so nothing falls into the open cylinder.

2.Verify the plug gap with extreme caution:Traditional coin-style gap tools will permanently snap the brittle 0.6mm tip.

Check your vehicle's specific under-hood emissions label for the required gap. If you must adjust or verify the gap on an iridium plug, use a wire loop gauge or a feeler gauge. Never apply any prying pressure or friction directly against the center iridium electrode. To widen the gap, use the dedicated bending slot on a gapping tool to gently pull the ground electrode back. To close it, gently tap the ground electrode on a clean surface.

3.Unscrew and extract the old spark plugs:Inspect the old plug tips for oil soaking or ash deposits.

Fit a dedicated 5/8-inch spark plug socket (which features an internal rubber retention insert or magnet) onto a long socket extension. Lower it down into the spark plug well until it seats firmly over the old hex nut. Attach your ratchet and turn counterclockwise to break the plug loose, keeping the extension perfectly straight to avoid cracking the ceramic insulator. Carefully lift the plug out of the well.

4.Hand-thread the new NGK plug into the cylinder head:Anti-seize compound acts as a lubricant and can cause dangerous overtightening.

Place the new NGK LFR6AIX-11 plug securely into your spark plug socket. Lower it into the well and turn the socket extension clockwise by hand only for at least 4 to 5 warm-up turns. This guarantees the steel threads align perfectly with the delicate aluminum threads of the cylinder head. If you feel any binding or resistance, stop immediately, back it out counterclockwise, and realign. Never use a power tool or ratchet to start a spark plug.

5.Torque the new spark plug to final seating specification:An under-torqued plug can back out; an over-torqued plug strips the head threads.

Once the plug is snug by hand, attach a torque wrench. For a 14mm thread size inside an aluminum cylinder head, torque the plug clockwise to 15 to 22 lb-ft (20 to 30 N·m). If you do not have a torque wrench, turn the plug by hand until the flat crush washer meets the metal seating face, then use a standard ratchet to turn it an additional 1/2 to 2/3 of a turn to fully compress the gasket.

6.Reinstall the ignition coils and test fire the engine:Listen for a distinct click or pop confirming a secure moisture seal.

Inspect the rubber boot of the ignition coil pack for cracks or heat degradation. Push the coil pack straight down over the terminal end of the new spark plug until it seats completely. Reinstall the small retaining bolt and tighten it snugly. Reattach the electrical harness plug to the coil. Reconnect the negative battery terminal, start the vehicle, and listen for a perfectly smooth engine idle.

1.Disconnect the ignition coil packs and clean the area:Allow the engine to cool completely to avoid stripping aluminum threads.

Park the vehicle on level ground and disconnect the negative battery terminal. Remove any plastic engine beauty covers. Locate the individual coil-on-plug units. Unplug the electrical wiring harness from the coil pack by depressing the locking tab, remove the retaining bolt (usually 10mm), and pull the coil straight up out of the spark plug well with a slight twisting motion. Use compressed air to blow any debris out of the deep well so nothing falls into the open cylinder.
2.Verify the plug gap with extreme caution:Traditional coin-style gap tools will permanently snap the brittle 0.6mm tip.

Check your vehicle's specific under-hood emissions label for the required gap. If you must adjust or verify the gap on an iridium plug, use a wire loop gauge or a feeler gauge. Never apply any prying pressure or friction directly against the center iridium electrode. To widen the gap, use the dedicated bending slot on a gapping tool to gently pull the ground electrode back. To close it, gently tap the ground electrode on a clean surface.
3.Unscrew and extract the old spark plugs:Inspect the old plug tips for oil soaking or ash deposits.

Fit a dedicated 5/8-inch spark plug socket (which features an internal rubber retention insert or magnet) onto a long socket extension. Lower it down into the spark plug well until it seats firmly over the old hex nut. Attach your ratchet and turn counterclockwise to break the plug loose, keeping the extension perfectly straight to avoid cracking the ceramic insulator. Carefully lift the plug out of the well.
4.Hand-thread the new NGK plug into the cylinder head:Anti-seize compound acts as a lubricant and can cause dangerous overtightening.

Place the new NGK LFR6AIX-11 plug securely into your spark plug socket. Lower it into the well and turn the socket extension clockwise by hand only for at least 4 to 5 warm-up turns. This guarantees the steel threads align perfectly with the delicate aluminum threads of the cylinder head. If you feel any binding or resistance, stop immediately, back it out counterclockwise, and realign. Never use a power tool or ratchet to start a spark plug.
5.Torque the new spark plug to final seating specification:An under-torqued plug can back out; an over-torqued plug strips the head threads.

Once the plug is snug by hand, attach a torque wrench. For a 14mm thread size inside an aluminum cylinder head, torque the plug clockwise to 15 to 22 lb-ft (20 to 30 N·m). If you do not have a torque wrench, turn the plug by hand until the flat crush washer meets the metal seating face, then use a standard ratchet to turn it an additional 1/2 to 2/3 of a turn to fully compress the gasket.
6.Reinstall the ignition coils and test fire the engine:Listen for a distinct click or pop confirming a secure moisture seal.

Inspect the rubber boot of the ignition coil pack for cracks or heat degradation. Push the coil pack straight down over the terminal end of the new spark plug until it seats completely. Reinstall the small retaining bolt and tighten it snugly. Reattach the electrical harness plug to the coil. Reconnect the negative battery terminal, start the vehicle, and listen for a perfectly smooth engine idle.

 

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