Engines are becoming more and more complex by the day. While installing the best spark plugs in your car is an easy task, long gone are the days when dads spent half their weekend getting greasy under their hoods. One of the only things left for car enthusiasts and hobbyists who love a little grease under their nails is the ability to change their spark plugs. Every other car problem out there needs a diagnostic scan tool and a college degree.
The best spark plugs may fire 25 million to 100 million times. Think of them as the tiniest bolt of lightning -- diminutive but mighty. The spark of electricity that your spark plugs emit across a small gap creates the explosion of energy needed to start your vehicle.
Spark plugs are a critical part of the internal combustion engine. Having spark plug problems can stop you in your tracks, literally. Spark plugs work by igniting the air and fuel mixture in the engine as efficiently as possible. If you have old, worn, or dirty spark plugs, it will significantly reduce your engine’s capacity to perform well. Therefore, replacing this little piece of hardware will ensure that your engine runs smoother, cleaner, and utilizes less fuel.
What Exactly Is a Spark Plug?
A spark plug is an electronic device installed in an internal combustion engine’s cylinder head. The spark plug ignites a compressed air and fuel mixture using an electric spark. The best spark plugs have an insulated center electrode, a metal casing, an insulator, and a ground electrode.
There are thousands of spark plugs available that function in a variety of internal combustion engines. Spark plugs are also installed in scooters, motorcycles, buses, trucks, tractors, boats, industrial and oil field engines, power mowers, and even chainsaws.
Your spark plugs sit at the top of the cylinder head. Your engine’s pistons (controlled by the camshaft) travel down the cylinder, drawing a mixture of air and fuel into the piston chamber. The piston then moves back up and compresses the mixture. When the piston gets to the TDC (top dead center) position, the spark plug is charged with electric current and ignites the mixture. This explosive action forces the piston back down, creating power for your engine. The piston is pushed back again to clear out the exhaust. And the process starts all over again.
When to Replace a spark plug
Your engine is a fine-tuned machine, so how can you tell if your spark plugs need attention? Performance, reliability, and fuel economy depends on consistent delivery of fuel, air, and spark. There are telltale signs when you need to replace your spark plugs.
Poor fuel economy
Faulty or worn out spark plugs will cause your engine to consume more fuel than it should. Since your Electronic Control Module (ECM) has control over the oxygen content and spark strength, it will add more fuel to the system to compensate for poor combustion conditions.
A misfire from the cylinders often occurs when the spark plugs are unable to ignite the engine’s air-fuel mixture. Misfires often happen due to worn out spark plugs, cracked plug housings, contamination, or other related problems.
Hard start issues
Difficulty in starting an engine occurs for many reasons. When an engine is cold, it is more difficult to get proper ignition of the fuel/air mixture in the cylinder. The ECM will add more fuel to account for poor vaporization, which can lead to excess fuel in the cylinder.
When your vehicle idles, you might notice slight vibrations. These are indicative of spark plug problems caused when a cylinder misfire occurs during idle.
When you notice hesitation on acceleration and surging, it might be described as an engine not responding immediately to driver input. Often a surge in power might come unexpectedly. This unexpected delay in power delivery might indicate a spark plug problem.
Types of Spark Plugs
Generally speaking, the best spark plugs all have a similar design. The Bosch 4417 Platinum +4 spark plug is an exception. It uses a 4-point ground electrode construction, with one center electrode. The main differences in the best spark plugs are in the materials used for the electrodes, and in some cases, the cap.
It is the original, but sadly, not the best spark plugs to have. Copper spark plugs are the most basic in the market, and also the least expensive. In modern cars, many manufacturers have shifted to platinum and iridium spark plugs.
Platinum is a great middle-ground material that provides a real boost in vehicle performance as well as fuel efficiency compared to copper spark plugs. For the best performance boost, look for spark plugs that use double platinum, both in the cap and electrodes.
It’s the best product out of spark plug technology. Iridium spark plugs give the best engine performance, best fuel economy, and exceptional durability. But this doesn’t come at a low cost.
Considerations to Make When Shopping for the Best Spark Plugs
Choosing the best spark plugs isn’t an easy task, there are dozens of choices that are available. Here are a few things to keep in mind.
It's best to stick to factory installed or Original Equipment Manufacturer (OEM) recommended plugs. Yttrium, platinum, or iridium plugs are much more expensive than traditional plugs. However, the coating provides much better wear resistance and maintains the gap for a much longer time. Avoid downgrading to less expensive plugs. Your savings will be quickly cut short by a shorter service life and lower gas mileage.
Some plugs have fixed gaps, while others have adjustable gaps. The gap, which is the measured space between the ground electrode and the center electrode, is essential. In case your auto parts retailer recommends a fixed gap, always check your vehicle manual to verify the correct gap. If your vehicle needs an adjustable gap spark plug, make sure that you check your manual for the correct gap. Adjust the gap accordingly before installation.
General pricing information
To have the best spark plugs installed by a certified mechanic will cost between $$ and $$$. Labor costs are estimated between $$ and $$$, while the parts cost will range between $ and $$. It's important to note that these estimates do not include fees and taxes. But you can save a lot of money by doing the job yourself if you are mechanically inclined.
How We Reviewed
To bring you an in-depth and independent review of the best spark plugs, we analyzed different spark plug brands. We based our findings on comparisons, affordability, functionality, reviews, and complaints from customers. We also checked manufacturer and dealer websites for more information on usage, reliability, and consumer feedback.
The 7 Best Spark Plugs
Despite their tiny size, spark plugs play a critical role in modern vehicles. The best spark plugs don’t just ensure your engine starts, but also that your car runs smoothly. In such a vast market, it’s a difficult task finding the best quality spark plugs for your car. We have compiled a list of seven of the best spark plugs today.
The NGK 6619 is a top-rated premium spark plug and one of the most cost-effective iridium plugs you can buy.
While you will be shelling out a lot of money to get these spark plugs compared to others, you will get a pack of six. Since you should always replace spark plugs as a set, this is an economical option.
The NGK 6619 are decent spark plugs all around and will give 25 percent more life than cheaper platinum spark plugs. Their super electrode wire also helps make this product a very efficient model.
The NGK 6619 Iridium plug, in a package of six, costs between $ and $$. It scores an impressive 4.5 out of 5 stars rating based on Amazon consumer reviews.
- Revolutionary surface air gap firing technology featuring four yttrium-enhanced ground electrodes delivers the longest,...
- Four yttrium-enhanced ground electrodes provide optimum access to the air/fuel mixture for the most efficient...
- Electrode gap is factory set to provide ease of installation - never requires adjustment
German manufacturer Bosch is known for making some of the best spark plugs in the motoring world. Therefore, when buying anything from them, you know you are getting a quality product. Their name guarantees it.
The Bosch 4417 Platinum +4 is a very innovative design. Its tip is redesigned from the ground up and looks very different from the traditional spark plug. Instead of a single ground electrode, Bosch 4417 Platinum +4 has four yttrium-enhanced ground electrodes.
The Bosch 4417 Platinum +4 delivers excellent service and performance with a heat-fused center electrode made from platinum. It has a straightforward design, and it is effortless to install. It comes ready to install, with no adjustments required before installation.
The Bosch 4417 Platinum +4 costs between $ and $ for a single piece, meaning a set of six will range from $ to $$. It scores a cool 4.6 out of 5 stars rating based on Amazon customer reviews.
- 0.4 mm iridium center electrode: world's smallest diameter that maximizes firing potential
- U-groove and taper cut ground electrode: provides faster spark flame growth and lessens heat quenching
- DENSO patented 360 degree laser welding process: ensuring exceptional quality bond and structural strength with the...
The Denso 5304 IK20 is a plug that doesn't disappoint. This price is high, but this is a premium product. It contains iridium tips and has a 0.4-millimeter width center electrode for better firing.
Iridium is undoubtedly the best spark plug material, and the thinner the electrode, the better its performance. Therefore, the Denso 5304 IK20 has the best material and the thinnest electrode on this list. It explains why the Denso 5304 IK20 offers such an incredible engine performance.
Each Denso 5304 IK20 plug costs between $ and $ and between $ to $ for a set of six. It has a 4.0 out of 5 stars rating based on Amazon consumer reviews.
- Copper Core Center Electrode: Allows for accurate control of heat range for longer life
- Maximum Corrosion Resistance: Thanks to a Patented Ultraseal coated shell
- Dependable and Durable: Built to ISO and SAE standards for proven performance
The Champion RE14MCC4 Copper Plus might be the cheapest spark plug in this list, but it is not a poor performer. This is one of the most basic spark plugs on the market.
The Champion RE14MCC4 Copper Plus is a nicely put together plug built with anti-corrosion resistance. It's durable, dependable, and made to a high standard for a longer lifespan. Older engines specify the use of copper plugs. Therefore, if your engine spec sheet calls for copper plugs, the Champion RE14MCC4 Copper Plus is an excellent option.
The Champion RE14MCC4 Copper Plus costs between $ and $ for a single plug or a reasonable $ to $ for a set of six. It has an impressive 4.8 out of 5 stars rating based on Amazon consumer reviews.
- Double Iridium firing pin and ground electrode inlay provide 4X longer service life compared to standard copper plugs
- 0.6mm fine wire firing pin provides superior ignitability and performance
- 360 Degree continuous laser weld fuses corrosion resistant iridium firing pin to base for increased durability
The purchase of Bosch 9652 means you are getting perhaps the best spark plugs in the market. The first guarantee is the brand name. The second guarantee is the iridium electrode and iridium cap. Bosch 9652 Double Iridium contains a substantial amount of iridium.
The Bosch 9652 Double Iridium lasts four times as long as a basic copper plug. It costs between $ and $ for a single plug or $ to $ for a six-plug set. It has a 4.1 out of 5 stars rating on Amazon.
- Designed specifically for the performance enthusiast, Iridium IX offers extreme ignitability, improved throttle response...
- The 0.6 millimeter laser welded fine Iridium tip ensures high durability and a consistently stable spark and the tapered...
- Longer insulator nose prevents fouling, the corrugated ribs on insulator prevents flashover, and a triple gasket seal...
The NGK 5464 BKR5EIX-11 is a high-performance vehicle spark plug. It is an iridium product and has a thin 0.6-millimeter center electrode that increases engine power and performance. The NGK 5464 BKR5EIX-11 is a unique spark plug. A triple gasket seal helps prevent any gas mixture leakage during combustion, which extracts every single ounce of power from the engine.
NGK 5464 BKR5EIX-11 costs between $ and $ for a single plug and $ to $$ for a set of six. It has a 4.4 out of 5 stars rating based on Amazon consumer reviews.
- Full platinum tips ensure virtually no gap erosion
- Works to optimize engine performance for a longer life and improved fuel economy
- Necked-down center electrode fires quicker and cleaner, with less voltage for easier starts and quicker acceleration
The Autolite APP104 spark plug is a superb everyday plug best for a standard car for everyday situations.
This Autolite spark plug is perfect for the standard drive to the mall or work. It the best spark plug for an average car to do normal things. Autolite APP104 spark plug costs between $ and $ for a single plug and $ to $ for a set of six. It has an impressive 4.5 out of 5 stars rating on Amazon.
Understanding how your vehicle’s spark plugs work is an essential step in increasing the life of your investment. Remember to check the manufacturer's specifications when selecting the best spark plugs for your vehicle.
Each vehicle has specific requirements to keep them running at top efficiency. Many online sites have vehicle selection apps to verify that you are ordering the correct part. Likewise, your local retailer will also be able to assist you in making a good choice.
Happy spark plug shopping!