2019 Jeep Grand Cherokee — Spark Plug Type, Gap & Torque Specs

As an ASE-certified master technician, I can tell you that the 2019 Jeep Grand Cherokee is a fantastic, versatile SUV, but it demands proper maintenance to keep its powertrains running smoothly. Whether you have the workhorse 3.6L Pentastar V6 or one of the mighty Hemi V8s, using the correct spark plugs, torquing them to spec, and replacing them at the right intervals is critical for fuel economy, performance, and preventing misfires.

Here is your comprehensive guide to the spark plug specifications, gaps, and replacement procedures for the 2019 Jeep Grand Cherokee.

Quick Reference

(Note: 5.7L, 6.4L, and 6.2L Hemi engines utilize a twin-spark design, requiring 2 spark plugs per cylinder—16 plugs total!)

Why the Right Plug Matters

Modern engines like the Pentastar and Hemi are highly sensitive to spark plug heat ranges and electrode materials. The OEM plugs for the 2019 Grand Cherokee are exclusively Iridium or double-platinum tipped.

• Iridium and Platinum vs. Copper: Iridium is significantly harder and more durable than platinum or copper, allowing for a fine-wire center electrode that concentrates the spark. This provides better combustion efficiency and allows for the 100,000-mile service intervals. Copper plugs simply will not survive in these modern, high-compression engines and will burn out rapidly.
• Heat Range: Installing a plug with the wrong heat range can lead to catastrophic engine failure. A plug that is too hot will cause pre-ignition (pinging or knocking), while a plug that is too cold will foul out with carbon deposits. Always stick to the OEM heat range cross-references.

How to Gap a Spark Plug

While most iridium and platinum spark plugs come pre-gapped from the factory, it is a best practice to verify the gap before installation in case the box was dropped during shipping.

1. Use the Right Tool: Use a wire-style gap gauge or a specialized feeler gauge. Avoid the cheap "coin-style" ramp gauges on iridium plugs, as they can easily snap the fragile fine-wire center electrode.
2. Check the Gap: Gently slide the wire gauge between the center and ground electrode. It should pass through with a slight "drag."
3. Adjust if Necessary: If the gap is too tight, use the bending tool on the gauge to slightly bend the ground strap up and away from the center electrode. Never pry directly against the iridium tip.

Replacement Procedure Tips

The 2019 Jeep Grand Cherokee uses a Coil-on-Plug (COP) ignition system, meaning there are no spark plug wires or distributors. Each cylinder has its own ignition coil sitting directly on top of the spark plug(s).

• 3.6L Pentastar V6: Replacing the plugs on the 3.6L requires removing the upper intake manifold (plenum) to access the driver's side bank of cylinders (cylinders 2, 4, 6). You will need a new set of upper intake manifold gaskets before starting this job. Ensure no debris falls into the lower intake ports while the plenum is off.
• 5.7L, 6.4L, and 6.2L Hemi V8s: The Hemi engines feature 16 spark plugs. The rear cylinders (especially cylinder 7 and 8 near the firewall) can be tricky to access. You will need a combination of locking extensions and universal swivel joints.
• Dielectric Grease: Apply a small pea-sized amount of dielectric grease to the inside of the ignition coil boot. This prevents the rubber boot from sticking to the spark plug porcelain over the next 100k miles and seals out moisture.
• The Anti-Seize Debate: NGK and Mopar explicitly advise against using anti-seize on these specific spark plugs. The OEM plugs feature a special trivalent metal plating that acts as a release agent. Adding anti-seize alters the thread friction, which frequently leads to over-torquing and breaking the plug flush in the cylinder head. Install them completely dry.

Known Issues

While the 2019 Jeep Grand Cherokee doesn't suffer from the infamous 2-piece spark plug breakage seen in older Ford 3-valve engines, there are a few things to watch for:

• Pentastar Ignition Coils: The factory ignition coils on the 3.6L can degrade due to heat cycling under the intake manifold. If you are replacing plugs at 100,000 miles and experiencing a misfire, it is highly recommended to test or replace the coils, especially on the bank hidden under the intake plenum to save yourself from doing the labor twice.
• Hemi Twin-Spark Boot Tearing: Because the Hemi coils have two boots (or a coil boot and a short jumper wire boot), the rubber often degrades and bakes onto the spark plug porcelain. Pull carefully, and be prepared to extract torn rubber boots from the spark plug tubes with long needle-nose pliers.

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