2016 Jeep Grand Cherokee Spark Plug Type & Gap

Quick Reference

Why the Right Plug Matters

Installing the correct spark plugs in your 2016 Jeep Grand Cherokee is crucial for optimal engine performance, fuel efficiency, and longevity. Spark plugs ignite the air-fuel mixture in your engine's cylinders, and an incorrect plug can lead to misfires, reduced power, rough idling, and even engine damage. Key factors to consider are heat range and electrode material.

Heat Range: This refers to the plug's ability to dissipate heat from the combustion chamber. A plug that's too "cold" (dissipates heat too quickly) can lead to carbon fouling, while a plug that's too "hot" (dissipates heat too slowly) can cause pre-ignition (pinging) and potentially melt engine components. Always stick to the manufacturer's recommended heat range.

Electrode Metal:

• Iridium: Found in the 3.6L Pentastar V6, iridium plugs are incredibly durable and have a fine-wire electrode, offering superior ignition and a longer lifespan (typically 100,000 miles). They are the most advanced and expensive option.
• Copper: Recommended for the 5.7L and 6.4L Hemi V8 engines, copper plugs have a larger diameter copper core for excellent conductivity. While less durable than iridium, their superior conductivity is preferred by some high-performance engines. They require more frequent replacement (around 30,000 miles).

How to Gap a Spark Plug

Properly gapping your spark plug ensures the correct spark intensity. While iridium and platinum plugs often come pre-gapped, it's always a good idea to double-check, especially with copper plugs. Use a wire-type spark plug gapping tool. Slide the tool's wire of the correct diameter between the center and ground electrodes until it fits snugly. If the gap is too small, gently pry the ground electrode open with the tool's adjuster. If it's too large, carefully tap the ground electrode on a hard, non-abrasive surface to close the gap slightly. Be extremely careful with fine-wire iridium and platinum plugs, as their delicate electrodes can be easily damaged.

Replacement Procedure Tips (3.6L Pentastar & 5.7L/6.4L Hemi)

Both the 3.6L Pentastar V6 and the 5.7L/6.4L Hemi V8 engines in the 2016 Grand Cherokee utilize a coil-on-plug ignition system, meaning each spark plug has its own ignition coil directly mounted on top of it. This eliminates traditional spark plug wires.

• Coil-on-Plug Removal: To access the spark plugs, you'll need to disconnect the electrical connector from each ignition coil and then remove the coil mounting bolt(s). Gently pull the coil straight up to remove it from the spark plug well. Avoid yanking or twisting.
• Anti-Seize Debate: While some mechanics recommend using a small amount of anti-seize compound on spark plug threads, many spark plug manufacturers (especially for modern nickel-plated plugs) advise against it. The nickel plating provides adequate anti-seize properties, and adding more can alter the torque readings, potentially leading to overtightening and thread damage. For your 2016 Grand Cherokee, if you choose to use it, apply a very thin coat sparingly on the threads only, avoiding the electrode tip or insulator.
• Dielectric Grease on Boots: Applying a small amount of dielectric grease inside the spark plug boot (the end that connects to the ceramic insulator of the spark plug) can facilitate easier installation and removal, and help seal out moisture. Be careful not to get grease on the electrode or inside the spark plug well.

Known Issues

Fortunately, the 2016 Jeep Grand Cherokee engines are not widely known for specific spark plug related issues such as cracked porcelain on Ford 3-valve engines or broken plug shells. However, general best practices for spark plug maintenance should always be followed to prevent problems:

• Misfires: A common symptom of failing spark plugs is an engine misfire, which can cause a rough idle, reduced power, and illuminate the check engine light. This often indicates a plug has worn out, fouled, or has a cracked insulator.
• Fouling: Oil, fuel, or carbon deposits can build up on the spark plug electrodes, preventing a strong spark. This is often a symptom of other engine problems that need to be addressed.

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