Choosing the Right Spark Plugs for Your 2014-2017 INFINITI QX50
Keep your QX50's 3.7L V6 engine running strong by understanding your spark plug options.
- Stick to OEM-equivalent Iridium spark plugs from NGK or Denso for the best performance and reliability in your QX50.
- Replacement is more complex than on many vehicles because the intake manifold must be removed to access the three rear spark plugs.
- Always replace intake manifold gaskets when changing the spark plugs to avoid future vacuum leaks.
- High-quality aftermarket plugs come pre-gapped; do not try to adjust them as you can easily damage the fine electrode tip.
Signs of Failing Spark Plugs
When your QX50's spark plugs begin to wear out, you'll notice changes in how your vehicle drives. Worn plugs can't create a strong, consistent spark, which leads to incomplete fuel combustion. Ignoring these signs can cause poor performance, worse fuel economy, and even damage to expensive parts like your catalytic converters.
- Engine Misfires or Stuttering: You may feel a hesitation or shaking from the engine, especially when accelerating. This is a classic sign that one or more plugs aren't firing correctly.
- Rough Idle: When your QX50 is stopped, the engine might vibrate or run unevenly. A bad spark plug disrupts the smooth firing sequence of the engine.
- Poor Acceleration: If your SUV feels sluggish or slow to respond when you press the gas pedal, worn plugs could be the culprit.
- Reduced Fuel Economy: When plugs don't fire efficiently, fuel is wasted. A worn-out plug can reduce your fuel economy by as much as 30%.
- Difficulty Starting: Old plugs can struggle to create a strong enough spark to start the engine, especially in cold weather.
Choosing the Right Aftermarket Spark Plugs
For the 2014-2017 QX50, the choice of spark plugs is straightforward. The original OEM plugs are made by either NGK or Denso, and these are the most highly recommended brands for replacement. Aftermarket options from these brands are identical to the OEM parts but often cost less.
Brand Quality Tiers for 2014-2017 QX50
| Tier | Brands | Notes |
|---|---|---|
| OEM-Equivalent (Best) | NGK, Denso | These are the original equipment manufacturers. Models like the NGK Laser Iridium (DILKAR7B11) and Denso Iridium Long Life (FXE24HR11) are direct-fit, pre-gapped replacements that will restore original performance and longevity. |
| High-Quality Aftermarket | Bosch | Bosch offers Iridium spark plugs that are a suitable alternative. While not the OEM supplier, they are a reputable brand that manufactures plugs to meet or exceed OEM specifications. |
| Standard Aftermarket | Champion, Autolite | These brands also offer compatible Iridium plugs. They can be a cost-effective option, but most INFINITI specialists and owners stick with NGK or Denso for proven reliability in the VQ37VHR engine. |
Installation Notes for DIY Replacement
Replacing the spark plugs on the QX50's 3.7L V6 is an intermediate-level job. While the three front plugs (passenger side) are easy to access, the three rear plugs (driver side) are located underneath the upper intake manifold. This manifold must be removed to access the rear plugs, making the job significantly more complex.
Pro Tip: Since you have to remove the intake manifold, it is highly recommended to replace the intake manifold gaskets and the throttle body gaskets at the same time to prevent vacuum leaks. Also, consider replacing the ignition coils on higher mileage vehicles (80,000+ miles) as a preventative measure, since you have to remove them anyway.
Frequently Asked Questions (FAQ)
When should I replace my QX50's spark plugs?
INFINITI's official maintenance schedule suggests a long interval, often around 105,000 miles. However, many mechanics and enthusiasts recommend replacing them between 60,000 and 90,000 miles as preventative maintenance to keep the engine running at its best and avoid issues like misfires.
Do I need to gap the new spark plugs?
No. High-quality iridium plugs from NGK, Denso, and Bosch come pre-gapped from the factory for your specific vehicle. Attempting to adjust the gap can easily damage the fine iridium tip, ruining the plug. Just install them directly out of the box.
Should I use anti-seize on the spark plug threads?
Most modern spark plugs from brands like NGK have a special trivalent metal plating that acts as its own anti-seize and anti-corrosion layer. Adding extra anti-seize can insulate the plug, affect heat dissipation, and lead to over-torquing. It is generally not recommended unless the plug manufacturer specifically states to use it.
Is it okay to replace only one bad spark plug?
It is strongly recommended to replace all six spark plugs at the same time. Spark plugs wear at a similar rate, so if one has failed, the others are likely near the end of their service life. Replacing them all at once ensures balanced engine performance and saves you from having to repeat the labor-intensive job in the near future.
Technical Specifications
OEM Part Numbers: 22401-JK01D
Material: Iridium, Quantity: 6, Recommended Brands: NGK (DILKAR7B11), Denso (FXE24HR11), Required Socket: 14mm Thin-Wall Spark Plug Socket.
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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.
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